From 772f8dd26d8d3bdc56e51f01c75cd569e68a8a1d Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Tue, 24 Nov 2015 09:37:12 -0800
Subject: [PATCH] Accept baselines

---
 ...addMoreOverloadsToBaseSignature.errors.txt |   2 +
 .../arityAndOrderCompatibility01.errors.txt   |  20 +-
 ...teralExpressionContextualTyping.errors.txt |  10 +-
 .../reference/arrayLiterals3.errors.txt       |  28 +-
 .../asOperatorContextualType.errors.txt       |   6 +-
 .../assignFromBooleanInterface2.errors.txt    |   6 +-
 .../baselines/reference/assignToFn.errors.txt |   2 +
 ...nmentCompatBetweenTupleAndArray.errors.txt |  10 +-
 .../reference/assignmentCompatBug5.errors.txt |  16 +-
 ...ignmentCompatWithCallSignatures.errors.txt |  80 +++---
 ...gnmentCompatWithCallSignatures2.errors.txt |  40 +--
 ...gnmentCompatWithCallSignatures4.errors.txt |  38 +--
 ...ignaturesWithOptionalParameters.errors.txt |  14 +
 ...allSignaturesWithRestParameters.errors.txt |  90 ++++---
 ...ntCompatWithConstructSignatures.errors.txt |  16 ++
 ...tCompatWithConstructSignatures2.errors.txt |   8 +
 ...tCompatWithConstructSignatures4.errors.txt |  82 +++---
 ...ignaturesWithOptionalParameters.errors.txt |  10 +
 ...ignaturesWithOptionalParameters.errors.txt |  12 +
 .../assignmentCompatWithOverloads.errors.txt  |  36 ++-
 .../assignmentCompatability24.errors.txt      |   4 +-
 .../assignmentCompatability33.errors.txt      |   4 +-
 .../assignmentCompatability34.errors.txt      |   4 +-
 .../assignmentCompatability37.errors.txt      |   4 +-
 .../assignmentCompatability38.errors.txt      |   4 +-
 .../reference/assignmentToObject.errors.txt   |   2 +
 .../assignmentToObjectAndFunction.errors.txt  |   6 +-
 .../asyncFunctionDeclaration15_es6.errors.txt |  20 +-
 .../reference/booleanAssignment.errors.txt    |  18 +-
 .../callConstructAssignment.errors.txt        |   6 +-
 ...atureAssignabilityInInheritance.errors.txt |   6 +-
 ...tureAssignabilityInInheritance3.errors.txt |  38 +--
 .../reference/castingTuple.errors.txt         |  10 +-
 ...ConstrainedToOtherTypeParameter.errors.txt |  10 +-
 ...onstrainedToOtherTypeParameter2.errors.txt |  12 +-
 ...ssignabilityConstructorFunction.errors.txt |   4 +-
 .../classSideInheritance3.errors.txt          |   4 +
 ...onalOperatorWithoutIdenticalBCT.errors.txt |  18 +-
 ...atureAssignabilityInInheritance.errors.txt |   6 +-
 ...tureAssignabilityInInheritance3.errors.txt |  38 +--
 .../reference/constructorAsType.errors.txt    |   2 +
 .../contextualTypeWithTuple.errors.txt        |  24 +-
 ...lTypeWithUnionTypeObjectLiteral.errors.txt |  10 +-
 .../reference/contextualTyping24.errors.txt   |  12 +-
 .../reference/contextualTyping39.errors.txt   |   6 +-
 .../reference/contextualTyping41.errors.txt   |   6 +-
 ...lTypingOfConditionalExpression2.errors.txt |  14 +-
 ...fGenericFunctionTypedArguments1.errors.txt |  16 +-
 .../derivedClassTransitivity.errors.txt       |  10 +-
 .../derivedClassTransitivity2.errors.txt      |  10 +-
 .../derivedClassTransitivity3.errors.txt      |  10 +-
 .../derivedClassTransitivity4.errors.txt      |  10 +-
 .../derivedInterfaceCallSignature.errors.txt  |   2 +
 ...tructuringParameterDeclaration2.errors.txt |  32 ++-
 .../reference/enumAssignability.errors.txt    |   6 +
 .../reference/errorElaboration.errors.txt     |  14 +-
 ...orOnContextuallyTypedReturnType.errors.txt |   6 +-
 ...AnnotationAndInvalidInitializer.errors.txt |  42 +--
 ...endAndImplementTheSameBaseType2.errors.txt |   6 +-
 ...fixingTypeParametersRepeatedly2.errors.txt |  16 +-
 tests/baselines/reference/for-of30.errors.txt |  16 +-
 tests/baselines/reference/for-of31.errors.txt |  24 +-
 ...functionConstraintSatisfaction2.errors.txt |  24 +-
 ...tionExpressionContextualTyping2.errors.txt |   6 +-
 ...ctionSignatureAssignmentCompat1.errors.txt |  10 +-
 .../reference/generatorTypeCheck25.errors.txt |  46 ++--
 .../reference/generatorTypeCheck31.errors.txt |   2 +
 .../reference/generatorTypeCheck8.errors.txt  |  10 +-
 ...AssignmentCompatWithInterfaces1.errors.txt |  10 +-
 ...edMethodWithOverloadedArguments.errors.txt |  40 +--
 ...lWithConstructorTypedArguments5.errors.txt |   4 +
 ...lWithGenericSignatureArguments2.errors.txt |  38 +--
 ...lWithGenericSignatureArguments3.errors.txt |  10 +-
 ...oadedConstructorTypedArguments2.errors.txt |   2 +
 ...erloadedFunctionTypedArguments2.errors.txt |   2 +
 .../genericCallWithTupleType.errors.txt       |  14 +-
 .../reference/genericCombinators2.errors.txt  |  16 +-
 .../genericSpecializations3.errors.txt        |  30 ++-
 .../genericTypeAssertions2.errors.txt         |  10 +-
 ...cTypeWithNonGenericBaseMisMatch.errors.txt |  40 +--
 .../baselines/reference/generics4.errors.txt  |   6 +-
 ...ementGenericWithMismatchedTypes.errors.txt |  16 +-
 .../reference/incompatibleTypes.errors.txt    |  26 +-
 .../reference/inheritance.errors.txt          |   2 +
 ...eMemberAccessorOverridingMethod.errors.txt |   2 +
 ...eStaticAccessorOverridingMethod.errors.txt |   2 +
 ...eStaticPropertyOverridingMethod.errors.txt |   2 +
 ...nheritedModuleMembersForClodule.errors.txt |   6 +-
 ...ceMemberAssignsToClassPrototype.errors.txt |   6 +-
 .../reference/intTypeCheck.errors.txt         |  42 ++-
 .../interfaceAssignmentCompat.errors.txt      |  14 +-
 .../interfaceImplementation1.errors.txt       |   2 +
 .../interfaceImplementation7.errors.txt       |  10 +-
 .../invalidBooleanAssignments.errors.txt      |   2 +
 .../iteratorSpreadInArray9.errors.txt         |  24 +-
 .../reference/lambdaArgCrash.errors.txt       |   2 +
 .../reference/multipleInheritance.errors.txt  |   2 +
 ...MembersOfObjectAssignmentCompat.errors.txt |  18 +-
 ...embersOfObjectAssignmentCompat2.errors.txt |  30 ++-
 ...mbersOfFunctionAssignmentCompat.errors.txt |   6 +-
 ...mbersOfFunctionAssignmentCompat.errors.txt |   6 +-
 ...ptionalFunctionArgAssignability.errors.txt |  20 +-
 .../optionalParamAssignmentCompat.errors.txt  |  10 +-
 .../optionalParamTypeComparison.errors.txt    |  20 +-
 .../overloadOnConstInheritance2.errors.txt    |   2 +
 .../overloadOnConstInheritance3.errors.txt    |   2 +
 .../overloadResolutionOverCTLambda.errors.txt |   6 +-
 ...nWithConstraintCheckingDeferred.errors.txt |  14 +-
 .../overloadsWithProvisionalErrors.errors.txt |  20 +-
 .../baselines/reference/parseTypes.errors.txt |   6 +
 .../reference/parser536727.errors.txt         |  12 +-
 ...serAutomaticSemicolonInsertion1.errors.txt |   4 +
 .../reference/promiseChaining1.errors.txt     |  10 +-
 .../reference/promiseChaining2.errors.txt     |  10 +-
 .../reference/promisePermutations.errors.txt  | 210 +++++++++------
 .../reference/promisePermutations2.errors.txt | 210 +++++++++------
 .../reference/promisePermutations3.errors.txt | 240 ++++++++++++------
 .../reference/propertyAssignment.errors.txt   |   6 +-
 tests/baselines/reference/qualify.errors.txt  |   4 +
 .../recursiveFunctionTypes.errors.txt         |  16 +-
 .../requiredInitializedParameter2.errors.txt  |   2 +
 .../restArgAssignmentCompat.errors.txt        |  14 +-
 ...gnsToConstructorFunctionMembers.errors.txt |   6 +-
 ...ypesAsTypeParameterConstraint02.errors.txt |   6 +-
 .../subtypingWithCallSignaturesA.errors.txt   |   6 +-
 ...ignaturesWithOptionalParameters.errors.txt |   4 +
 ...allSignaturesWithRestParameters.errors.txt | 110 ++++----
 ...aturesWithSpecializedSignatures.errors.txt |   6 +-
 ...ignaturesWithOptionalParameters.errors.txt |   4 +
 ...aturesWithSpecializedSignatures.errors.txt |   6 +-
 ...ignaturesWithOptionalParameters.errors.txt |  12 +
 ...ignaturesWithOptionalParameters.errors.txt |  12 +
 .../reference/symbolProperty24.errors.txt     |   6 +-
 .../reference/targetTypeVoidFunc.errors.txt   |   2 +
 .../baselines/reference/tupleTypes.errors.txt |  20 +-
 ...entInferenceConstructSignatures.errors.txt |  30 ++-
 .../typeArgumentInferenceErrors.errors.txt    |  30 ++-
 ...ntInferenceWithClassExpression2.errors.txt |  10 +-
 ...rgumentInferenceWithConstraints.errors.txt |  30 ++-
 .../typeGuardFunctionErrors.errors.txt        |  28 +-
 .../baselines/reference/typeName1.errors.txt  |   4 +
 ...ypeParameterArgumentEquivalence.errors.txt |  20 +-
 ...peParameterArgumentEquivalence2.errors.txt |  20 +-
 ...peParameterArgumentEquivalence3.errors.txt |  12 +-
 ...peParameterArgumentEquivalence4.errors.txt |  12 +-
 ...peParameterArgumentEquivalence5.errors.txt |  24 +-
 ...gWithContextSensitiveArguments2.errors.txt |  10 +-
 ...gWithContextSensitiveArguments3.errors.txt |  10 +-
 .../typesWithPrivateConstructor.errors.txt    |   2 +
 .../typesWithPublicConstructor.errors.txt     |   2 +
 .../undeclaredModuleError.errors.txt          |   6 +-
 151 files changed, 1874 insertions(+), 992 deletions(-)

diff --git a/tests/baselines/reference/addMoreOverloadsToBaseSignature.errors.txt b/tests/baselines/reference/addMoreOverloadsToBaseSignature.errors.txt
index 4b6255688f8..be20b673287 100644
--- a/tests/baselines/reference/addMoreOverloadsToBaseSignature.errors.txt
+++ b/tests/baselines/reference/addMoreOverloadsToBaseSignature.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/addMoreOverloadsToBaseSignature.ts(5,11): error TS2430: Interface 'Bar' incorrectly extends interface 'Foo'.
   Types of property 'f' are incompatible.
     Type '(key: string) => string' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in '(key: string) => string'
 
 
 ==== tests/cases/compiler/addMoreOverloadsToBaseSignature.ts (1 errors) ====
@@ -13,6 +14,7 @@ tests/cases/compiler/addMoreOverloadsToBaseSignature.ts(5,11): error TS2430: Int
 !!! error TS2430: Interface 'Bar' incorrectly extends interface 'Foo'.
 !!! error TS2430:   Types of property 'f' are incompatible.
 !!! error TS2430:     Type '(key: string) => string' is not assignable to type '() => string'.
+!!! error TS2430:       Signature '(): string' has no corresponding signature in '(key: string) => string'
         f(key: string): string;
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/arityAndOrderCompatibility01.errors.txt b/tests/baselines/reference/arityAndOrderCompatibility01.errors.txt
index d60f0b7d03c..a766bab8a96 100644
--- a/tests/baselines/reference/arityAndOrderCompatibility01.errors.txt
+++ b/tests/baselines/reference/arityAndOrderCompatibility01.errors.txt
@@ -29,13 +29,15 @@ tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(24,5): error
 tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(25,5): error TS2322: Type '[string, number]' is not assignable to type '[string]'.
   Types of property 'pop' are incompatible.
     Type '() => string | number' is not assignable to type '() => string'.
-      Type 'string | number' is not assignable to type 'string'.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => string | number'
+        Type 'string | number' is not assignable to type 'string'.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(26,5): error TS2322: Type 'StrNum' is not assignable to type '[string]'.
   Types of property 'pop' are incompatible.
     Type '() => string | number' is not assignable to type '() => string'.
-      Type 'string | number' is not assignable to type 'string'.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => string | number'
+        Type 'string | number' is not assignable to type 'string'.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(27,5): error TS2322: Type '{ 0: string; 1: number; }' is not assignable to type '[string]'.
   Property 'length' is missing in type '{ 0: string; 1: number; }'.
 tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(28,5): error TS2322: Type '[string, number]' is not assignable to type '[number, string]'.
@@ -120,15 +122,17 @@ tests/cases/conformance/types/tuple/arityAndOrderCompatibility01.ts(30,5): error
 !!! error TS2322: Type '[string, number]' is not assignable to type '[string]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => string | number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'string | number' is not assignable to type 'string'.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => string | number'
+!!! error TS2322:         Type 'string | number' is not assignable to type 'string'.
+!!! error TS2322:           Type 'number' is not assignable to type 'string'.
     var m2: [string] = y;
         ~~
 !!! error TS2322: Type 'StrNum' is not assignable to type '[string]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => string | number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'string | number' is not assignable to type 'string'.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => string | number'
+!!! error TS2322:         Type 'string | number' is not assignable to type 'string'.
+!!! error TS2322:           Type 'number' is not assignable to type 'string'.
     var m3: [string] = z;
         ~~
 !!! error TS2322: Type '{ 0: string; 1: number; }' is not assignable to type '[string]'.
diff --git a/tests/baselines/reference/arrayLiteralExpressionContextualTyping.errors.txt b/tests/baselines/reference/arrayLiteralExpressionContextualTyping.errors.txt
index 72ba1411320..b7ea49c7283 100644
--- a/tests/baselines/reference/arrayLiteralExpressionContextualTyping.errors.txt
+++ b/tests/baselines/reference/arrayLiteralExpressionContextualTyping.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/expressions/contextualTyping/arrayLiteralExpressionContextualTyping.ts(8,5): error TS2322: Type '[number, number, number, string]' is not assignable to type '[number, number, number]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string' is not assignable to type '() => number'.
-      Type 'number | string' is not assignable to type 'number'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | string'
+        Type 'number | string' is not assignable to type 'number'.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/contextualTyping/arrayLiteralExpressionContextualTyping.ts(14,5): error TS2322: Type 'number[]' is not assignable to type '[number, number, number]'.
   Property '0' is missing in type 'number[]'.
 
@@ -20,8 +21,9 @@ tests/cases/conformance/expressions/contextualTyping/arrayLiteralExpressionConte
 !!! error TS2322: Type '[number, number, number, string]' is not assignable to type '[number, number, number]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | string' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'number | string' is not assignable to type 'number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => number | string'
+!!! error TS2322:         Type 'number | string' is not assignable to type 'number'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     
     // In a contextually typed array literal expression containing one or more spread elements,
     // an element expression at index N is contextually typed by the numeric index type of the contextual type, if any.
diff --git a/tests/baselines/reference/arrayLiterals3.errors.txt b/tests/baselines/reference/arrayLiterals3.errors.txt
index 637fb3e3bc4..a3d3611cf55 100644
--- a/tests/baselines/reference/arrayLiterals3.errors.txt
+++ b/tests/baselines/reference/arrayLiterals3.errors.txt
@@ -6,8 +6,9 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(11,5): error
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(17,5): error TS2322: Type '[number, number, string, boolean]' is not assignable to type '[number, number]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string | boolean' is not assignable to type '() => number'.
-      Type 'number | string | boolean' is not assignable to type 'number'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | string | boolean'
+        Type 'number | string | boolean' is not assignable to type 'number'.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(32,5): error TS2322: Type '(number[] | string[])[]' is not assignable to type 'tup'.
   Property '0' is missing in type '(number[] | string[])[]'.
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(33,5): error TS2322: Type 'number[]' is not assignable to type '[number, number, number]'.
@@ -15,10 +16,11 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(33,5): error
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error TS2322: Type '(number | string)[]' is not assignable to type 'myArray'.
   Types of property 'push' are incompatible.
     Type '(...items: (number | string)[]) => number' is not assignable to type '(...items: Number[]) => number'.
-      Types of parameters 'items' and 'items' are incompatible.
-        Type 'number | string' is not assignable to type 'Number'.
-          Type 'string' is not assignable to type 'Number'.
-            Property 'toFixed' is missing in type 'String'.
+      Signature '(...items: Number[]): number' has no corresponding signature in '(...items: (number | string)[]) => number'
+        Types of parameters 'items' and 'items' are incompatible.
+          Type 'number | string' is not assignable to type 'Number'.
+            Type 'string' is not assignable to type 'Number'.
+              Property 'toFixed' is missing in type 'String'.
 
 
 ==== tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts (6 errors) ====
@@ -50,8 +52,9 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
 !!! error TS2322: Type '[number, number, string, boolean]' is not assignable to type '[number, number]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | string | boolean' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'number | string | boolean' is not assignable to type 'number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => number | string | boolean'
+!!! error TS2322:         Type 'number | string | boolean' is not assignable to type 'number'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     
     // The resulting type an array literal expression is determined as follows:
     //      - the resulting type is an array type with an element type that is the union of the types of the
@@ -79,8 +82,9 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
 !!! error TS2322: Type '(number | string)[]' is not assignable to type 'myArray'.
 !!! error TS2322:   Types of property 'push' are incompatible.
 !!! error TS2322:     Type '(...items: (number | string)[]) => number' is not assignable to type '(...items: Number[]) => number'.
-!!! error TS2322:       Types of parameters 'items' and 'items' are incompatible.
-!!! error TS2322:         Type 'number | string' is not assignable to type 'Number'.
-!!! error TS2322:           Type 'string' is not assignable to type 'Number'.
-!!! error TS2322:             Property 'toFixed' is missing in type 'String'.
+!!! error TS2322:       Signature '(...items: Number[]): number' has no corresponding signature in '(...items: (number | string)[]) => number'
+!!! error TS2322:         Types of parameters 'items' and 'items' are incompatible.
+!!! error TS2322:           Type 'number | string' is not assignable to type 'Number'.
+!!! error TS2322:             Type 'string' is not assignable to type 'Number'.
+!!! error TS2322:               Property 'toFixed' is missing in type 'String'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/asOperatorContextualType.errors.txt b/tests/baselines/reference/asOperatorContextualType.errors.txt
index c53b407b5cf..6c52114625b 100644
--- a/tests/baselines/reference/asOperatorContextualType.errors.txt
+++ b/tests/baselines/reference/asOperatorContextualType.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/expressions/asOperator/asOperatorContextualType.ts(2,9): error TS2352: Neither type '(v: number) => number' nor type '(x: number) => string' is assignable to the other.
-  Type 'number' is not assignable to type 'string'.
+  Signature '(x: number): string' has no corresponding signature in '(v: number) => number'
+    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/expressions/asOperator/asOperatorContextualType.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/conformance/expressions/asOperator/asOperatorContextualType.ts(2,9):
     var x = (v => v) as (x: number) => string;
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2352: Neither type '(v: number) => number' nor type '(x: number) => string' is assignable to the other.
-!!! error TS2352:   Type 'number' is not assignable to type 'string'.
\ No newline at end of file
+!!! error TS2352:   Signature '(x: number): string' has no corresponding signature in '(v: number) => number'
+!!! error TS2352:     Type 'number' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
index c03eab60c74..f20050a5b9e 100644
--- a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
+++ b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(14,1): error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
   Types of property 'valueOf' are incompatible.
     Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+      Signature '(): boolean' has no corresponding signature in '() => Object'
+        Type 'Object' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(19,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(20,1): error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
 
@@ -25,7 +26,8 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
 !!! error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
 !!! error TS2322:   Types of property 'valueOf' are incompatible.
 !!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:       Signature '(): boolean' has no corresponding signature in '() => Object'
+!!! error TS2322:         Type 'Object' is not assignable to type 'boolean'.
     
     b = a;
     b = x;
diff --git a/tests/baselines/reference/assignToFn.errors.txt b/tests/baselines/reference/assignToFn.errors.txt
index 7f2c7855a35..2b2b2a5366f 100644
--- a/tests/baselines/reference/assignToFn.errors.txt
+++ b/tests/baselines/reference/assignToFn.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignToFn.ts(8,5): error TS2322: Type 'string' is not assignable to type '(n: number) => boolean'.
+  Signature '(n: number): boolean' has no corresponding signature in 'String'
 
 
 ==== tests/cases/compiler/assignToFn.ts (1 errors) ====
@@ -12,5 +13,6 @@ tests/cases/compiler/assignToFn.ts(8,5): error TS2322: Type 'string' is not assi
         x.f="hello";
         ~~~
 !!! error TS2322: Type 'string' is not assignable to type '(n: number) => boolean'.
+!!! error TS2322:   Signature '(n: number): boolean' has no corresponding signature in 'String'
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatBetweenTupleAndArray.errors.txt b/tests/baselines/reference/assignmentCompatBetweenTupleAndArray.errors.txt
index c7552c3fdb2..16fff660c1d 100644
--- a/tests/baselines/reference/assignmentCompatBetweenTupleAndArray.errors.txt
+++ b/tests/baselines/reference/assignmentCompatBetweenTupleAndArray.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatBetweenTupleAndArray.ts(17,1): error TS2322: Type '[number, string]' is not assignable to type 'number[]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string' is not assignable to type '() => number'.
-      Type 'number | string' is not assignable to type 'number'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | string'
+        Type 'number | string' is not assignable to type 'number'.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatBetweenTupleAndArray.ts(18,1): error TS2322: Type '{}[]' is not assignable to type '[{}]'.
   Property '0' is missing in type '{}[]'.
 
@@ -29,8 +30,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type '[number, string]' is not assignable to type 'number[]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | string' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'number | string' is not assignable to type 'number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => number | string'
+!!! error TS2322:         Type 'number | string' is not assignable to type 'number'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     emptyObjTuple = emptyObjArray;
     ~~~~~~~~~~~~~
 !!! error TS2322: Type '{}[]' is not assignable to type '[{}]'.
diff --git a/tests/baselines/reference/assignmentCompatBug5.errors.txt b/tests/baselines/reference/assignmentCompatBug5.errors.txt
index 1b5e3d80259..f8b1a1094e2 100644
--- a/tests/baselines/reference/assignmentCompatBug5.errors.txt
+++ b/tests/baselines/reference/assignmentCompatBug5.errors.txt
@@ -3,10 +3,12 @@ tests/cases/compiler/assignmentCompatBug5.ts(2,8): error TS2345: Argument of typ
 tests/cases/compiler/assignmentCompatBug5.ts(5,6): error TS2345: Argument of type 'string[]' is not assignable to parameter of type 'number[]'.
   Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/assignmentCompatBug5.ts(8,6): error TS2345: Argument of type '(s: string) => void' is not assignable to parameter of type '(n: number) => number'.
-  Types of parameters 's' and 'n' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(n: number): number' has no corresponding signature in '(s: string) => void'
+    Types of parameters 's' and 'n' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/assignmentCompatBug5.ts(9,6): error TS2345: Argument of type '(n: number) => void' is not assignable to parameter of type '(n: number) => number'.
-  Type 'void' is not assignable to type 'number'.
+  Signature '(n: number): number' has no corresponding signature in '(n: number) => void'
+    Type 'void' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/assignmentCompatBug5.ts (4 errors) ====
@@ -26,11 +28,13 @@ tests/cases/compiler/assignmentCompatBug5.ts(9,6): error TS2345: Argument of typ
     foo3((s:string) => { });
          ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(s: string) => void' is not assignable to parameter of type '(n: number) => number'.
-!!! error TS2345:   Types of parameters 's' and 'n' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(n: number): number' has no corresponding signature in '(s: string) => void'
+!!! error TS2345:     Types of parameters 's' and 'n' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     foo3((n) => { return; });
          ~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(n: number) => void' is not assignable to parameter of type '(n: number) => number'.
-!!! error TS2345:   Type 'void' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(n: number): number' has no corresponding signature in '(n: number) => void'
+!!! error TS2345:     Type 'void' is not assignable to type 'number'.
     
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatWithCallSignatures.errors.txt b/tests/baselines/reference/assignmentCompatWithCallSignatures.errors.txt
index 6a221ef144e..194b1834a61 100644
--- a/tests/baselines/reference/assignmentCompatWithCallSignatures.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithCallSignatures.errors.txt
@@ -1,27 +1,35 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(35,1): error TS2322: Type 'S2' is not assignable to type 'T'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in 'S2'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(36,1): error TS2322: Type '(x: string) => void' is not assignable to type 'T'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(37,1): error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => number'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(38,1): error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(39,1): error TS2322: Type 'S2' is not assignable to type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in 'S2'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(40,1): error TS2322: Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(41,1): error TS2322: Type '(x: string) => number' is not assignable to type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => number'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts(42,1): error TS2322: Type '(x: string) => string' is not assignable to type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures.ts (8 errors) ====
@@ -62,41 +70,49 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
     t = s2;
     ~
 !!! error TS2322: Type 'S2' is not assignable to type 'T'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in 'S2'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     t = a3;
     ~
 !!! error TS2322: Type '(x: string) => void' is not assignable to type 'T'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     t = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => number'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     t = function (x: string) { return ''; }
     ~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     a = s2;
     ~
 !!! error TS2322: Type 'S2' is not assignable to type '(x: number) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in 'S2'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     a = a3;
     ~
 !!! error TS2322: Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     a = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type '(x: number) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => number'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     a = function (x: string) { return ''; }
     ~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type '(x: number) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatWithCallSignatures2.errors.txt b/tests/baselines/reference/assignmentCompatWithCallSignatures2.errors.txt
index e67f0a930c2..fdcc9fe6ec9 100644
--- a/tests/baselines/reference/assignmentCompatWithCallSignatures2.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithCallSignatures2.errors.txt
@@ -9,13 +9,15 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(42,1): error TS2322: Type 'S2' is not assignable to type 'T'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(43,1): error TS2322: Type '{ f(x: string): void; }' is not assignable to type 'T'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(44,1): error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
   Property 'f' is missing in type '(x: string) => number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(45,1): error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
@@ -23,13 +25,15 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(46,1): error TS2322: Type 'S2' is not assignable to type '{ f(x: number): void; }'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(47,1): error TS2322: Type '{ f(x: string): void; }' is not assignable to type '{ f(x: number): void; }'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(48,1): error TS2322: Type '(x: string) => number' is not assignable to type '{ f(x: number): void; }'.
   Property 'f' is missing in type '(x: string) => number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures2.ts(49,1): error TS2322: Type '(x: string) => string' is not assignable to type '{ f(x: number): void; }'.
@@ -95,15 +99,17 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'S2' is not assignable to type 'T'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     t = a3;
     ~
 !!! error TS2322: Type '{ f(x: string): void; }' is not assignable to type 'T'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     t = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
@@ -117,15 +123,17 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'S2' is not assignable to type '{ f(x: number): void; }'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     a = a3;
     ~
 !!! error TS2322: Type '{ f(x: string): void; }' is not assignable to type '{ f(x: number): void; }'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     a = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type '{ f(x: number): void; }'.
diff --git a/tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt b/tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt
index e00d1eea042..3620fb0e8c3 100644
--- a/tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt
@@ -1,13 +1,16 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts(52,9): error TS2322: Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-      Types of parameters 'arg2' and 'arg2' are incompatible.
-        Type '{ foo: number; }' is not assignable to type 'Base'.
-          Types of property 'foo' are incompatible.
-            Type 'number' is not assignable to type 'string'.
+  Signature '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+        Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+          Types of parameters 'arg2' and 'arg2' are incompatible.
+            Type '{ foo: number; }' is not assignable to type 'Base'.
+              Types of property 'foo' are incompatible.
+                Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts(53,9): error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
+  Signature '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U): (r: T) => U' has no corresponding signature in '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts (2 errors) ====
@@ -65,17 +68,20 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
             a8 = b8; // error, { foo: number } and Base are incompatible
             ~~
 !!! error TS2322: Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-!!! error TS2322:       Types of parameters 'arg2' and 'arg2' are incompatible.
-!!! error TS2322:         Type '{ foo: number; }' is not assignable to type 'Base'.
-!!! error TS2322:           Types of property 'foo' are incompatible.
-!!! error TS2322:             Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+!!! error TS2322:         Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+!!! error TS2322:           Types of parameters 'arg2' and 'arg2' are incompatible.
+!!! error TS2322:             Type '{ foo: number; }' is not assignable to type 'Base'.
+!!! error TS2322:               Types of property 'foo' are incompatible.
+!!! error TS2322:                 Type 'number' is not assignable to type 'string'.
             b8 = a8; // error, { foo: number } and Base are incompatible
             ~~
 !!! error TS2322: Type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
+!!! error TS2322:   Signature '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U): (r: T) => U' has no corresponding signature in '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
     
             
             var b10: <T extends Derived>(...x: T[]) => T; 
diff --git a/tests/baselines/reference/assignmentCompatWithCallSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/assignmentCompatWithCallSignaturesWithOptionalParameters.errors.txt
index f89bbfa5798..504f6d70799 100644
--- a/tests/baselines/reference/assignmentCompatWithCallSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithCallSignaturesWithOptionalParameters.errors.txt
@@ -1,10 +1,17 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(16,5): error TS2322: Type '(x: number) => number' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(x: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(19,5): error TS2322: Type '(x: number) => number' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(x: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(20,5): error TS2322: Type '(x: number, y?: number) => number' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(x: number, y?: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(22,5): error TS2322: Type '(x: number, y: number) => number' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(x: number, y: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(33,5): error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x?: number) => number'.
+  Signature '(x?: number): number' has no corresponding signature in '(x: number, y: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(39,5): error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+  Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts(45,5): error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+  Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithOptionalParameters.ts (7 errors) ====
@@ -26,18 +33,22 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a = (x: number) => 1; // error, too many required params
         ~
 !!! error TS2322: Type '(x: number) => number' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(x: number) => number'
         a = b.a; // ok
         a = b.a2; // ok
         a = b.a3; // error
         ~
 !!! error TS2322: Type '(x: number) => number' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(x: number) => number'
         a = b.a4; // error
         ~
 !!! error TS2322: Type '(x: number, y?: number) => number' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(x: number, y?: number) => number'
         a = b.a5; // ok
         a = b.a6; // error
         ~
 !!! error TS2322: Type '(x: number, y: number) => number' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(x: number, y: number) => number'
     
     var a2: (x?: number) => number; 
         a2 = () => 1; // ok, same number of required params
@@ -51,6 +62,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a2 = b.a6; // error
         ~~
 !!! error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x?: number) => number'.
+!!! error TS2322:   Signature '(x?: number): number' has no corresponding signature in '(x: number, y: number) => number'
     
     var a3: (x: number) => number; 
         a3 = () => 1; // ok, fewer required params
@@ -59,6 +71,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a3 = (x: number, y: number) => 1;  // error, too many required params
         ~~
 !!! error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+!!! error TS2322:   Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
         a3 = b.a; // ok
         a3 = b.a2; // ok
         a3 = b.a3; // ok
@@ -67,6 +80,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a3 = b.a6; // error
         ~~
 !!! error TS2322: Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+!!! error TS2322:   Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
     
     var a4: (x: number, y?: number) => number;
         a4 = () => 1; // ok, fewer required params
diff --git a/tests/baselines/reference/assignmentCompatWithCallSignaturesWithRestParameters.errors.txt b/tests/baselines/reference/assignmentCompatWithCallSignaturesWithRestParameters.errors.txt
index 8eec8503e70..e785ab663ca 100644
--- a/tests/baselines/reference/assignmentCompatWithCallSignaturesWithRestParameters.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithCallSignaturesWithRestParameters.errors.txt
@@ -1,30 +1,39 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(13,5): error TS2322: Type '(...args: string[]) => number' is not assignable to type '(...args: number[]) => number'.
-  Types of parameters 'args' and 'args' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(...args: number[]): number' has no corresponding signature in '(...args: string[]) => number'
+    Types of parameters 'args' and 'args' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(17,5): error TS2322: Type '(x?: string) => number' is not assignable to type '(...args: number[]) => number'.
-  Types of parameters 'x' and 'args' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(...args: number[]): number' has no corresponding signature in '(x?: string) => number'
+    Types of parameters 'x' and 'args' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(26,5): error TS2322: Type '(x: number, ...args: string[]) => number' is not assignable to type '(x: number, ...z: number[]) => number'.
-  Types of parameters 'args' and 'z' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+    Types of parameters 'args' and 'z' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(35,5): error TS2322: Type '(x: number, y?: number, z?: number) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number, z?: number) => number'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(36,5): error TS2322: Type '(x: number, ...z: number[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'z' and 'y' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: number[]) => number'
+    Types of parameters 'z' and 'y' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(37,5): error TS2322: Type '(x: string, y?: string, z?: string) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: string, y?: string, z?: string) => number'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(41,5): error TS2322: Type '(x?: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x?: number, y?: number) => number'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(43,5): error TS2322: Type '(x: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number) => number'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts(45,5): error TS2322: Type '(x: number, ...args: string[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-  Types of parameters 'args' and 'z' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+    Types of parameters 'args' and 'z' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignaturesWithRestParameters.ts (9 errors) ====
@@ -43,16 +52,18 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a = (...args: string[]) => 1; // error, type mismatch
         ~
 !!! error TS2322: Type '(...args: string[]) => number' is not assignable to type '(...args: number[]) => number'.
-!!! error TS2322:   Types of parameters 'args' and 'args' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(...args: number[]): number' has no corresponding signature in '(...args: string[]) => number'
+!!! error TS2322:     Types of parameters 'args' and 'args' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
         a = (x?: number) => 1; // ok, same number of required params
         a = (x?: number, y?: number, z?: number) => 1; // ok, same number of required params
         a = (x: number) => 1; // ok, rest param corresponds to infinite number of params
         a = (x?: string) => 1; // error, incompatible type
         ~
 !!! error TS2322: Type '(x?: string) => number' is not assignable to type '(...args: number[]) => number'.
-!!! error TS2322:   Types of parameters 'x' and 'args' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(...args: number[]): number' has no corresponding signature in '(x?: string) => number'
+!!! error TS2322:     Types of parameters 'x' and 'args' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     
     
     var a2: (x: number, ...z: number[]) => number;
@@ -64,8 +75,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a2 = (x: number, ...args: string[]) => 1; // should be type mismatch error
         ~~
 !!! error TS2322: Type '(x: number, ...args: string[]) => number' is not assignable to type '(x: number, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'args' and 'z' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+!!! error TS2322:     Types of parameters 'args' and 'z' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
         a2 = (x: number, y: number) => 1; // ok, rest param corresponds to infinite number of params
         a2 = (x: number, y?: number) => 1; // ok, same number of required params
     
@@ -77,35 +89,41 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a3 = (x: number, y?: number, z?: number) => 1;  // error
         ~~
 !!! error TS2322: Type '(x: number, y?: number, z?: number) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number, z?: number) => number'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
         a3 = (x: number, ...z: number[]) => 1;  // error
         ~~
 !!! error TS2322: Type '(x: number, ...z: number[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'z' and 'y' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: number[]) => number'
+!!! error TS2322:     Types of parameters 'z' and 'y' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
         a3 = (x: string, y?: string, z?: string) => 1;  // error
         ~~
 !!! error TS2322: Type '(x: string, y?: string, z?: string) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: string, y?: string, z?: string) => number'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     
     var a4: (x?: number, y?: string, ...z: number[]) => number;
         a4 = () => 1; // ok, fewer required params
         a4 = (x?: number, y?: number) => 1; // error, type mismatch
         ~~
 !!! error TS2322: Type '(x?: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x?: number, y?: number) => number'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
         a4 = (x: number) => 1; // ok, all present params match
         a4 = (x: number, y?: number) => 1;  // error, second param has type mismatch
         ~~
 !!! error TS2322: Type '(x: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number) => number'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
         a4 = (x?: number, y?: string) => 1;  // ok, same number of required params with matching types
         a4 = (x: number, ...args: string[]) => 1;  // error, rest params have type mismatch
         ~~
 !!! error TS2322: Type '(x: number, ...args: string[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2322:   Types of parameters 'args' and 'z' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2322:   Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+!!! error TS2322:     Types of parameters 'args' and 'z' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatWithConstructSignatures.errors.txt b/tests/baselines/reference/assignmentCompatWithConstructSignatures.errors.txt
index 9c0c0d6a8fd..dfefb83af2f 100644
--- a/tests/baselines/reference/assignmentCompatWithConstructSignatures.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithConstructSignatures.errors.txt
@@ -1,11 +1,19 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(28,1): error TS2322: Type 'S2' is not assignable to type 'T'.
+  Signature 'new (x: number): void' has no corresponding signature in 'S2'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(29,1): error TS2322: Type '(x: string) => void' is not assignable to type 'T'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(30,1): error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(31,1): error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => string'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(32,1): error TS2322: Type 'S2' is not assignable to type 'new (x: number) => void'.
+  Signature 'new (x: number): void' has no corresponding signature in 'S2'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(33,1): error TS2322: Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(34,1): error TS2322: Type '(x: string) => number' is not assignable to type 'new (x: number) => void'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts(35,1): error TS2322: Type '(x: string) => string' is not assignable to type 'new (x: number) => void'.
+  Signature 'new (x: number): void' has no corresponding signature in '(x: string) => string'
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures.ts (8 errors) ====
@@ -39,25 +47,33 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
     t = s2;
     ~
 !!! error TS2322: Type 'S2' is not assignable to type 'T'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in 'S2'
     t = a3;
     ~
 !!! error TS2322: Type '(x: string) => void' is not assignable to type 'T'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     t = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => number'
     t = function (x: string) { return ''; }
     ~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => string'
     a = s2;
     ~
 !!! error TS2322: Type 'S2' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in 'S2'
     a = a3;
     ~
 !!! error TS2322: Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     a = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => number'
     a = function (x: string) { return ''; }
     ~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in '(x: string) => string'
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatWithConstructSignatures2.errors.txt b/tests/baselines/reference/assignmentCompatWithConstructSignatures2.errors.txt
index 5e8fc6dd3a4..ab181157b6e 100644
--- a/tests/baselines/reference/assignmentCompatWithConstructSignatures2.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithConstructSignatures2.errors.txt
@@ -9,9 +9,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(34,1): error TS2322: Type 'S2' is not assignable to type 'T'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+      Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(35,1): error TS2322: Type '{ f(x: string): void; }' is not assignable to type 'T'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+      Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(36,1): error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
   Property 'f' is missing in type '(x: string) => number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(37,1): error TS2322: Type '(x: string) => string' is not assignable to type 'T'.
@@ -19,9 +21,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(38,1): error TS2322: Type 'S2' is not assignable to type '{ f: new (x: number) => void; }'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+      Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(39,1): error TS2322: Type '{ f(x: string): void; }' is not assignable to type '{ f: new (x: number) => void; }'.
   Types of property 'f' are incompatible.
     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+      Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(40,1): error TS2322: Type '(x: string) => number' is not assignable to type '{ f: new (x: number) => void; }'.
   Property 'f' is missing in type '(x: string) => number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures2.ts(41,1): error TS2322: Type '(x: string) => string' is not assignable to type '{ f: new (x: number) => void; }'.
@@ -79,11 +83,13 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'S2' is not assignable to type 'T'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:       Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     t = a3;
     ~
 !!! error TS2322: Type '{ f(x: string): void; }' is not assignable to type 'T'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:       Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     t = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type 'T'.
@@ -97,11 +103,13 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'S2' is not assignable to type '{ f: new (x: number) => void; }'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:       Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     a = a3;
     ~
 !!! error TS2322: Type '{ f(x: string): void; }' is not assignable to type '{ f: new (x: number) => void; }'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type 'new (x: number) => void'.
+!!! error TS2322:       Signature 'new (x: number): void' has no corresponding signature in '(x: string) => void'
     a = (x: string) => 1;
     ~
 !!! error TS2322: Type '(x: string) => number' is not assignable to type '{ f: new (x: number) => void; }'.
diff --git a/tests/baselines/reference/assignmentCompatWithConstructSignatures4.errors.txt b/tests/baselines/reference/assignmentCompatWithConstructSignatures4.errors.txt
index 804e31600e1..3a771411b53 100644
--- a/tests/baselines/reference/assignmentCompatWithConstructSignatures4.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithConstructSignatures4.errors.txt
@@ -1,25 +1,34 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(52,9): error TS2322: Type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-      Types of parameters 'arg2' and 'arg2' are incompatible.
-        Type '{ foo: number; }' is not assignable to type 'Base'.
-          Types of property 'foo' are incompatible.
-            Type 'number' is not assignable to type 'string'.
+  Signature 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+        Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+          Types of parameters 'arg2' and 'arg2' are incompatible.
+            Type '{ foo: number; }' is not assignable to type 'Base'.
+              Types of property 'foo' are incompatible.
+                Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(53,9): error TS2322: Type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
-  Types of parameters 'y' and 'y' are incompatible.
-    Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
+  Signature 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U): (r: T) => U' has no corresponding signature in 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'
+    Types of parameters 'y' and 'y' are incompatible.
+      Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(77,9): error TS2322: Type 'new <T>(x: (a: T) => T) => T[]' is not assignable to type '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type '(a: any) => any' is not assignable to type '{ new (a: number): number; new (a?: number): number; }'.
+  Signature 'new (x: { new (a: number): number; new (a?: number): number; }): number[]' has no corresponding signature in 'new <T>(x: (a: T) => T) => T[]'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type '(a: any) => any' is not assignable to type '{ new (a: number): number; new (a?: number): number; }'.
+        Signature 'new (a: number): number' has no corresponding signature in '(a: any) => any'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(78,9): error TS2322: Type '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }' is not assignable to type 'new <T>(x: (a: T) => T) => T[]'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type '{ new (a: number): number; new (a?: number): number; }' is not assignable to type '(a: any) => any'.
+  Signature 'new <T>(x: (a: T) => T): T[]' has no corresponding signature in '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type '{ new (a: number): number; new (a?: number): number; }' is not assignable to type '(a: any) => any'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(81,9): error TS2322: Type 'new <T>(x: (a: T) => T) => any[]' is not assignable to type '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type '(a: any) => any' is not assignable to type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }'.
+  Signature 'new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]' has no corresponding signature in 'new <T>(x: (a: T) => T) => any[]'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type '(a: any) => any' is not assignable to type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }'.
+        Signature 'new <T extends Derived>(a: T): T' has no corresponding signature in '(a: any) => any'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts(82,9): error TS2322: Type '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }' is not assignable to type 'new <T>(x: (a: T) => T) => any[]'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }' is not assignable to type '(a: any) => any'.
+  Signature 'new <T>(x: (a: T) => T): any[]' has no corresponding signature in '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }' is not assignable to type '(a: any) => any'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts (6 errors) ====
@@ -77,17 +86,20 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
             a8 = b8; // error, type mismatch
             ~~
 !!! error TS2322: Type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-!!! error TS2322:       Types of parameters 'arg2' and 'arg2' are incompatible.
-!!! error TS2322:         Type '{ foo: number; }' is not assignable to type 'Base'.
-!!! error TS2322:           Types of property 'foo' are incompatible.
-!!! error TS2322:             Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+!!! error TS2322:         Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+!!! error TS2322:           Types of parameters 'arg2' and 'arg2' are incompatible.
+!!! error TS2322:             Type '{ foo: number; }' is not assignable to type 'Base'.
+!!! error TS2322:               Types of property 'foo' are incompatible.
+!!! error TS2322:                 Type 'number' is not assignable to type 'string'.
             b8 = a8; // error
             ~~
 !!! error TS2322: Type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived' is not assignable to type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'.
-!!! error TS2322:   Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:     Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
+!!! error TS2322:   Signature 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U): (r: T) => U' has no corresponding signature in 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'
+!!! error TS2322:     Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:       Type '(arg2: Base) => Derived' is not assignable to type '(arg2: { foo: number; }) => any'.
     
             
             var b10: new <T extends Derived>(...x: T[]) => T; 
@@ -114,25 +126,31 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
             a16 = b16; // error
             ~~~
 !!! error TS2322: Type 'new <T>(x: (a: T) => T) => T[]' is not assignable to type '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type '(a: any) => any' is not assignable to type '{ new (a: number): number; new (a?: number): number; }'.
+!!! error TS2322:   Signature 'new (x: { new (a: number): number; new (a?: number): number; }): number[]' has no corresponding signature in 'new <T>(x: (a: T) => T) => T[]'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type '(a: any) => any' is not assignable to type '{ new (a: number): number; new (a?: number): number; }'.
+!!! error TS2322:         Signature 'new (a: number): number' has no corresponding signature in '(a: any) => any'
             b16 = a16; // error
             ~~~
 !!! error TS2322: Type '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }' is not assignable to type 'new <T>(x: (a: T) => T) => T[]'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type '{ new (a: number): number; new (a?: number): number; }' is not assignable to type '(a: any) => any'.
+!!! error TS2322:   Signature 'new <T>(x: (a: T) => T): T[]' has no corresponding signature in '{ new (x: { new (a: number): number; new (a?: number): number; }): number[]; new (x: { new (a: boolean): boolean; new (a?: boolean): boolean; }): boolean[]; }'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type '{ new (a: number): number; new (a?: number): number; }' is not assignable to type '(a: any) => any'.
     
             var b17: new <T>(x: (a: T) => T) => any[];
             a17 = b17; // error
             ~~~
 !!! error TS2322: Type 'new <T>(x: (a: T) => T) => any[]' is not assignable to type '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type '(a: any) => any' is not assignable to type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }'.
+!!! error TS2322:   Signature 'new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]' has no corresponding signature in 'new <T>(x: (a: T) => T) => any[]'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type '(a: any) => any' is not assignable to type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }'.
+!!! error TS2322:         Signature 'new <T extends Derived>(a: T): T' has no corresponding signature in '(a: any) => any'
             b17 = a17; // error
             ~~~
 !!! error TS2322: Type '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }' is not assignable to type 'new <T>(x: (a: T) => T) => any[]'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }' is not assignable to type '(a: any) => any'.
+!!! error TS2322:   Signature 'new <T>(x: (a: T) => T): any[]' has no corresponding signature in '{ new (x: { new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }): any[]; new (x: { new <T extends Derived2>(a: T): T; new <T extends Base>(a: T): T; }): any[]; }'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type '{ new <T extends Derived>(a: T): T; new <T extends Base>(a: T): T; }' is not assignable to type '(a: any) => any'.
         }
     
         module WithGenericSignaturesInBaseType {
diff --git a/tests/baselines/reference/assignmentCompatWithConstructSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/assignmentCompatWithConstructSignaturesWithOptionalParameters.errors.txt
index df56af3ee98..4ba4ec9a3c3 100644
--- a/tests/baselines/reference/assignmentCompatWithConstructSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithConstructSignaturesWithOptionalParameters.errors.txt
@@ -1,8 +1,13 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(16,5): error TS2322: Type 'new (x: number) => number' is not assignable to type 'new () => number'.
+  Signature 'new (): number' has no corresponding signature in 'new (x: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(17,5): error TS2322: Type 'new (x: number, y?: number) => number' is not assignable to type 'new () => number'.
+  Signature 'new (): number' has no corresponding signature in 'new (x: number, y?: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(19,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new () => number'.
+  Signature 'new (): number' has no corresponding signature in 'new (x: number, y: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(27,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number) => number'.
+  Signature 'new (x?: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts(35,5): error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
+  Signature 'new (x: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignaturesWithOptionalParameters.ts (5 errors) ====
@@ -24,13 +29,16 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a = b.a3; // error
         ~
 !!! error TS2322: Type 'new (x: number) => number' is not assignable to type 'new () => number'.
+!!! error TS2322:   Signature 'new (): number' has no corresponding signature in 'new (x: number) => number'
         a = b.a4; // error
         ~
 !!! error TS2322: Type 'new (x: number, y?: number) => number' is not assignable to type 'new () => number'.
+!!! error TS2322:   Signature 'new (): number' has no corresponding signature in 'new (x: number, y?: number) => number'
         a = b.a5; // ok
         a = b.a6; // error
         ~
 !!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new () => number'.
+!!! error TS2322:   Signature 'new (): number' has no corresponding signature in 'new (x: number, y: number) => number'
     
     var a2: new (x?: number) => number; 
         a2 = b.a; // ok
@@ -41,6 +49,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a2 = b.a6; // error
         ~~
 !!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x?: number) => number'.
+!!! error TS2322:   Signature 'new (x?: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
     
     var a3: new (x: number) => number; 
         a3 = b.a; // ok
@@ -51,6 +60,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
         a3 = b.a6; // error
         ~~
 !!! error TS2322: Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
+!!! error TS2322:   Signature 'new (x: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
     
     var a4: new (x: number, y?: number) => number;
         a4 = b.a; // ok
diff --git a/tests/baselines/reference/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.errors.txt
index a18da8fd8f7..229ec114d39 100644
--- a/tests/baselines/reference/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.errors.txt
@@ -1,9 +1,15 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(14,13): error TS2322: Type '(x: T) => any' is not assignable to type '() => T'.
+  Signature '(): T' has no corresponding signature in '(x: T) => any'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(23,13): error TS2322: Type '(x: T, y: T) => any' is not assignable to type '(x: T) => T'.
+  Signature '(x: T): T' has no corresponding signature in '(x: T, y: T) => any'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(65,9): error TS2322: Type '(x: T) => T' is not assignable to type '<T>() => T'.
+  Signature '<T>(): T' has no corresponding signature in '(x: T) => T'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(66,9): error TS2322: Type '(x: T, y?: T) => T' is not assignable to type '<T>() => T'.
+  Signature '<T>(): T' has no corresponding signature in '(x: T, y?: T) => T'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(107,13): error TS2322: Type '<T>(x: T) => any' is not assignable to type '<T>() => T'.
+  Signature '<T>(): T' has no corresponding signature in '<T>(x: T) => any'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts(116,13): error TS2322: Type '<T>(x: T, y: T) => any' is not assignable to type '<T>(x: T) => T'.
+  Signature '<T>(x: T): T' has no corresponding signature in '<T>(x: T, y: T) => any'
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithGenericCallSignaturesWithOptionalParameters.ts (6 errors) ====
@@ -23,6 +29,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
                 this.a = (x: T) => null; // error, too many required params
                 ~~~~~~
 !!! error TS2322: Type '(x: T) => any' is not assignable to type '() => T'.
+!!! error TS2322:   Signature '(): T' has no corresponding signature in '(x: T) => any'
     
                 this.a2 = () => null; // ok, same T of required params
                 this.a2 = (x?: T) => null; // ok, same T of required params
@@ -34,6 +41,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
                 this.a3 = (x: T, y: T) => null;  // error, too many required params
                 ~~~~~~~
 !!! error TS2322: Type '(x: T, y: T) => any' is not assignable to type '(x: T) => T'.
+!!! error TS2322:   Signature '(x: T): T' has no corresponding signature in '(x: T, y: T) => any'
     
                 this.a4 = () => null; // ok, fewer required params
                 this.a4 = (x?: T, y?: T) => null; // ok, fewer required params
@@ -78,9 +86,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
             b.a = t.a3;
             ~~~
 !!! error TS2322: Type '(x: T) => T' is not assignable to type '<T>() => T'.
+!!! error TS2322:   Signature '<T>(): T' has no corresponding signature in '(x: T) => T'
             b.a = t.a4;
             ~~~
 !!! error TS2322: Type '(x: T, y?: T) => T' is not assignable to type '<T>() => T'.
+!!! error TS2322:   Signature '<T>(): T' has no corresponding signature in '(x: T, y?: T) => T'
             b.a = t.a5;
     
             b.a2 = t.a;
@@ -124,6 +134,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
                 this.a = <T>(x: T) => null; // error, too many required params
                 ~~~~~~
 !!! error TS2322: Type '<T>(x: T) => any' is not assignable to type '<T>() => T'.
+!!! error TS2322:   Signature '<T>(): T' has no corresponding signature in '<T>(x: T) => any'
     
                 this.a2 = <T>() => null; // ok, same T of required params
                 this.a2 = <T>(x?: T) => null; // ok, same T of required params
@@ -135,6 +146,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
                 this.a3 = <T>(x: T, y: T) => null;  // error, too many required params
                 ~~~~~~~
 !!! error TS2322: Type '<T>(x: T, y: T) => any' is not assignable to type '<T>(x: T) => T'.
+!!! error TS2322:   Signature '<T>(x: T): T' has no corresponding signature in '<T>(x: T, y: T) => any'
     
                 this.a4 = <T>() => null; // ok, fewer required params
                 this.a4 = <T>(x?: T, y?: T) => null; // ok, fewer required params
diff --git a/tests/baselines/reference/assignmentCompatWithOverloads.errors.txt b/tests/baselines/reference/assignmentCompatWithOverloads.errors.txt
index 3bea0c46716..1def25bf372 100644
--- a/tests/baselines/reference/assignmentCompatWithOverloads.errors.txt
+++ b/tests/baselines/reference/assignmentCompatWithOverloads.errors.txt
@@ -1,13 +1,17 @@
 tests/cases/compiler/assignmentCompatWithOverloads.ts(17,1): error TS2322: Type '(x: string) => string' is not assignable to type '(s1: string) => number'.
-  Type 'string' is not assignable to type 'number'.
-tests/cases/compiler/assignmentCompatWithOverloads.ts(19,1): error TS2322: Type '(x: number) => number' is not assignable to type '(s1: string) => number'.
-  Types of parameters 'x' and 's1' are incompatible.
-    Type 'number' is not assignable to type 'string'.
-tests/cases/compiler/assignmentCompatWithOverloads.ts(21,1): error TS2322: Type '{ (x: string): string; (x: number): number; }' is not assignable to type '(s1: string) => number'.
-  Type 'string' is not assignable to type 'number'.
-tests/cases/compiler/assignmentCompatWithOverloads.ts(30,1): error TS2322: Type 'typeof C' is not assignable to type 'new (x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
+  Signature '(s1: string): number' has no corresponding signature in '(x: string) => string'
     Type 'string' is not assignable to type 'number'.
+tests/cases/compiler/assignmentCompatWithOverloads.ts(19,1): error TS2322: Type '(x: number) => number' is not assignable to type '(s1: string) => number'.
+  Signature '(s1: string): number' has no corresponding signature in '(x: number) => number'
+    Types of parameters 'x' and 's1' are incompatible.
+      Type 'number' is not assignable to type 'string'.
+tests/cases/compiler/assignmentCompatWithOverloads.ts(21,1): error TS2322: Type '{ (x: string): string; (x: number): number; }' is not assignable to type '(s1: string) => number'.
+  Signature '(s1: string): number' has no corresponding signature in '{ (x: string): string; (x: number): number; }'
+    Type 'string' is not assignable to type 'number'.
+tests/cases/compiler/assignmentCompatWithOverloads.ts(30,1): error TS2322: Type 'typeof C' is not assignable to type 'new (x: number) => void'.
+  Signature 'new (x: number): void' has no corresponding signature in 'typeof C'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/assignmentCompatWithOverloads.ts (4 errors) ====
@@ -30,18 +34,21 @@ tests/cases/compiler/assignmentCompatWithOverloads.ts(30,1): error TS2322: Type
     g = f2; // Error
     ~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type '(s1: string) => number'.
-!!! error TS2322:   Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(s1: string): number' has no corresponding signature in '(x: string) => string'
+!!! error TS2322:     Type 'string' is not assignable to type 'number'.
     
     g = f3; // Error
     ~
 !!! error TS2322: Type '(x: number) => number' is not assignable to type '(s1: string) => number'.
-!!! error TS2322:   Types of parameters 'x' and 's1' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(s1: string): number' has no corresponding signature in '(x: number) => number'
+!!! error TS2322:     Types of parameters 'x' and 's1' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
     
     g = f4; // Error
     ~
 !!! error TS2322: Type '{ (x: string): string; (x: number): number; }' is not assignable to type '(s1: string) => number'.
-!!! error TS2322:   Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(s1: string): number' has no corresponding signature in '{ (x: string): string; (x: number): number; }'
+!!! error TS2322:     Type 'string' is not assignable to type 'number'.
     
     class C {
         constructor(x: string);
@@ -53,5 +60,6 @@ tests/cases/compiler/assignmentCompatWithOverloads.ts(30,1): error TS2322: Type
     d = C; // Error
     ~
 !!! error TS2322: Type 'typeof C' is not assignable to type 'new (x: number) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2322:   Signature 'new (x: number): void' has no corresponding signature in 'typeof C'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatability24.errors.txt b/tests/baselines/reference/assignmentCompatability24.errors.txt
index 0f4a535d413..69c0bd2b288 100644
--- a/tests/baselines/reference/assignmentCompatability24.errors.txt
+++ b/tests/baselines/reference/assignmentCompatability24.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignmentCompatability24.ts(9,1): error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
+  Signature '<Tstring>(a: Tstring): Tstring' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
 
 
 ==== tests/cases/compiler/assignmentCompatability24.ts (1 errors) ====
@@ -12,4 +13,5 @@ tests/cases/compiler/assignmentCompatability24.ts(9,1): error TS2322: Type 'inte
     }
     __test2__.__val__obj = __test1__.__val__obj4
     ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
\ No newline at end of file
+!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
+!!! error TS2322:   Signature '<Tstring>(a: Tstring): Tstring' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatability33.errors.txt b/tests/baselines/reference/assignmentCompatability33.errors.txt
index e2352625280..50e173b1202 100644
--- a/tests/baselines/reference/assignmentCompatability33.errors.txt
+++ b/tests/baselines/reference/assignmentCompatability33.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignmentCompatability33.ts(9,1): error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
+  Signature '<Tstring>(a: Tstring): Tstring' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
 
 
 ==== tests/cases/compiler/assignmentCompatability33.ts (1 errors) ====
@@ -12,4 +13,5 @@ tests/cases/compiler/assignmentCompatability33.ts(9,1): error TS2322: Type 'inte
     }
     __test2__.__val__obj = __test1__.__val__obj4
     ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
\ No newline at end of file
+!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tstring>(a: Tstring) => Tstring'.
+!!! error TS2322:   Signature '<Tstring>(a: Tstring): Tstring' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatability34.errors.txt b/tests/baselines/reference/assignmentCompatability34.errors.txt
index 2dd9cba6470..2f0bca9dff2 100644
--- a/tests/baselines/reference/assignmentCompatability34.errors.txt
+++ b/tests/baselines/reference/assignmentCompatability34.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignmentCompatability34.ts(9,1): error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tnumber>(a: Tnumber) => Tnumber'.
+  Signature '<Tnumber>(a: Tnumber): Tnumber' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
 
 
 ==== tests/cases/compiler/assignmentCompatability34.ts (1 errors) ====
@@ -12,4 +13,5 @@ tests/cases/compiler/assignmentCompatability34.ts(9,1): error TS2322: Type 'inte
     }
     __test2__.__val__obj = __test1__.__val__obj4
     ~~~~~~~~~~~~~~~~~~~~
-!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tnumber>(a: Tnumber) => Tnumber'.
\ No newline at end of file
+!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type '<Tnumber>(a: Tnumber) => Tnumber'.
+!!! error TS2322:   Signature '<Tnumber>(a: Tnumber): Tnumber' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatability37.errors.txt b/tests/baselines/reference/assignmentCompatability37.errors.txt
index 452b72fe8ff..f965d49a0da 100644
--- a/tests/baselines/reference/assignmentCompatability37.errors.txt
+++ b/tests/baselines/reference/assignmentCompatability37.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignmentCompatability37.ts(9,1): error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tnumber>(param: Tnumber) => any'.
+  Signature 'new <Tnumber>(param: Tnumber): any' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
 
 
 ==== tests/cases/compiler/assignmentCompatability37.ts (1 errors) ====
@@ -12,4 +13,5 @@ tests/cases/compiler/assignmentCompatability37.ts(9,1): error TS2322: Type 'inte
     }
     __test2__.__val__aa = __test1__.__val__obj4
     ~~~~~~~~~~~~~~~~~~~
-!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tnumber>(param: Tnumber) => any'.
\ No newline at end of file
+!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tnumber>(param: Tnumber) => any'.
+!!! error TS2322:   Signature 'new <Tnumber>(param: Tnumber): any' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentCompatability38.errors.txt b/tests/baselines/reference/assignmentCompatability38.errors.txt
index 5f7918374c1..1a5540065cc 100644
--- a/tests/baselines/reference/assignmentCompatability38.errors.txt
+++ b/tests/baselines/reference/assignmentCompatability38.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/assignmentCompatability38.ts(9,1): error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tstring>(param: Tstring) => any'.
+  Signature 'new <Tstring>(param: Tstring): any' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
 
 
 ==== tests/cases/compiler/assignmentCompatability38.ts (1 errors) ====
@@ -12,4 +13,5 @@ tests/cases/compiler/assignmentCompatability38.ts(9,1): error TS2322: Type 'inte
     }
     __test2__.__val__aa = __test1__.__val__obj4
     ~~~~~~~~~~~~~~~~~~~
-!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tstring>(param: Tstring) => any'.
\ No newline at end of file
+!!! error TS2322: Type 'interfaceWithPublicAndOptional<number, string>' is not assignable to type 'new <Tstring>(param: Tstring) => any'.
+!!! error TS2322:   Signature 'new <Tstring>(param: Tstring): any' has no corresponding signature in 'interfaceWithPublicAndOptional<number, string>'
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentToObject.errors.txt b/tests/baselines/reference/assignmentToObject.errors.txt
index aa1222bd799..796f8430b84 100644
--- a/tests/baselines/reference/assignmentToObject.errors.txt
+++ b/tests/baselines/reference/assignmentToObject.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/assignmentToObject.ts(3,5): error TS2322: Type '{ toString: number; }' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type 'number' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in 'Number'
 
 
 ==== tests/cases/compiler/assignmentToObject.ts (1 errors) ====
@@ -11,4 +12,5 @@ tests/cases/compiler/assignmentToObject.ts(3,5): error TS2322: Type '{ toString:
 !!! error TS2322: Type '{ toString: number; }' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type 'number' is not assignable to type '() => string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in 'Number'
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignmentToObjectAndFunction.errors.txt b/tests/baselines/reference/assignmentToObjectAndFunction.errors.txt
index 2e85ee101f5..881b29bf443 100644
--- a/tests/baselines/reference/assignmentToObjectAndFunction.errors.txt
+++ b/tests/baselines/reference/assignmentToObjectAndFunction.errors.txt
@@ -1,11 +1,13 @@
 tests/cases/compiler/assignmentToObjectAndFunction.ts(1,5): error TS2322: Type '{ toString: number; }' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type 'number' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in 'Number'
 tests/cases/compiler/assignmentToObjectAndFunction.ts(8,5): error TS2322: Type '{}' is not assignable to type 'Function'.
   Property 'apply' is missing in type '{}'.
 tests/cases/compiler/assignmentToObjectAndFunction.ts(29,5): error TS2322: Type 'typeof bad' is not assignable to type 'Function'.
   Types of property 'apply' are incompatible.
     Type 'number' is not assignable to type '(thisArg: any, argArray?: any) => any'.
+      Signature '(thisArg: any, argArray?: any): any' has no corresponding signature in 'Number'
 
 
 ==== tests/cases/compiler/assignmentToObjectAndFunction.ts (3 errors) ====
@@ -14,6 +16,7 @@ tests/cases/compiler/assignmentToObjectAndFunction.ts(29,5): error TS2322: Type
 !!! error TS2322: Type '{ toString: number; }' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type 'number' is not assignable to type '() => string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in 'Number'
     var goodObj: Object = {
         toString(x?) {
             return "";
@@ -48,4 +51,5 @@ tests/cases/compiler/assignmentToObjectAndFunction.ts(29,5): error TS2322: Type
         ~~~~~~~~~~
 !!! error TS2322: Type 'typeof bad' is not assignable to type 'Function'.
 !!! error TS2322:   Types of property 'apply' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type '(thisArg: any, argArray?: any) => any'.
\ No newline at end of file
+!!! error TS2322:     Type 'number' is not assignable to type '(thisArg: any, argArray?: any) => any'.
+!!! error TS2322:       Signature '(thisArg: any, argArray?: any): any' has no corresponding signature in 'Number'
\ No newline at end of file
diff --git a/tests/baselines/reference/asyncFunctionDeclaration15_es6.errors.txt b/tests/baselines/reference/asyncFunctionDeclaration15_es6.errors.txt
index bc1ef24127a..8aa24d79ac0 100644
--- a/tests/baselines/reference/asyncFunctionDeclaration15_es6.errors.txt
+++ b/tests/baselines/reference/asyncFunctionDeclaration15_es6.errors.txt
@@ -3,10 +3,12 @@ tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration1
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration15_es6.ts(8,16): error TS1055: Type 'number' is not a valid async function return type.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration15_es6.ts(9,16): error TS1055: Type 'PromiseLike' is not a valid async function return type.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration15_es6.ts(10,16): error TS1055: Type 'typeof Thenable' is not a valid async function return type.
-  Type 'Thenable' is not assignable to type 'PromiseLike<any>'.
-    Types of property 'then' are incompatible.
-      Type '() => void' is not assignable to type '{ <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>; <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => void): PromiseLike<TResult>; }'.
-        Type 'void' is not assignable to type 'PromiseLike<any>'.
+  Signature 'new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void): PromiseLike<T>' has no corresponding signature in 'typeof Thenable'
+    Type 'Thenable' is not assignable to type 'PromiseLike<any>'.
+      Types of property 'then' are incompatible.
+        Type '() => void' is not assignable to type '{ <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>; <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => void): PromiseLike<TResult>; }'.
+          Signature '<TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>' has no corresponding signature in '() => void'
+            Type 'void' is not assignable to type 'PromiseLike<any>'.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration15_es6.ts(17,16): error TS1059: Return expression in async function does not have a valid callable 'then' member.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration15_es6.ts(23,25): error TS1058: Operand for 'await' does not have a valid callable 'then' member.
 
@@ -32,10 +34,12 @@ tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration1
     async function fn6(): Thenable { } // error
                    ~~~
 !!! error TS1055: Type 'typeof Thenable' is not a valid async function return type.
-!!! error TS1055:   Type 'Thenable' is not assignable to type 'PromiseLike<any>'.
-!!! error TS1055:     Types of property 'then' are incompatible.
-!!! error TS1055:       Type '() => void' is not assignable to type '{ <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>; <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => void): PromiseLike<TResult>; }'.
-!!! error TS1055:         Type 'void' is not assignable to type 'PromiseLike<any>'.
+!!! error TS1055:   Signature 'new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void): PromiseLike<T>' has no corresponding signature in 'typeof Thenable'
+!!! error TS1055:     Type 'Thenable' is not assignable to type 'PromiseLike<any>'.
+!!! error TS1055:       Types of property 'then' are incompatible.
+!!! error TS1055:         Type '() => void' is not assignable to type '{ <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>; <TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => void): PromiseLike<TResult>; }'.
+!!! error TS1055:           Signature '<TResult>(onfulfilled?: (value: any) => TResult | PromiseLike<TResult>, onrejected?: (reason: any) => TResult | PromiseLike<TResult>): PromiseLike<TResult>' has no corresponding signature in '() => void'
+!!! error TS1055:             Type 'void' is not assignable to type 'PromiseLike<any>'.
     async function fn7() { return; } // valid: Promise<void>
     async function fn8() { return 1; } // valid: Promise<number>
     async function fn9() { return null; } // valid: Promise<any>
diff --git a/tests/baselines/reference/booleanAssignment.errors.txt b/tests/baselines/reference/booleanAssignment.errors.txt
index 454bd7ef707..b16cca5c1bb 100644
--- a/tests/baselines/reference/booleanAssignment.errors.txt
+++ b/tests/baselines/reference/booleanAssignment.errors.txt
@@ -1,15 +1,18 @@
 tests/cases/compiler/booleanAssignment.ts(2,1): error TS2322: Type 'number' is not assignable to type 'Boolean'.
   Types of property 'valueOf' are incompatible.
     Type '() => number' is not assignable to type '() => boolean'.
-      Type 'number' is not assignable to type 'boolean'.
+      Signature '(): boolean' has no corresponding signature in '() => number'
+        Type 'number' is not assignable to type 'boolean'.
 tests/cases/compiler/booleanAssignment.ts(3,1): error TS2322: Type 'string' is not assignable to type 'Boolean'.
   Types of property 'valueOf' are incompatible.
     Type '() => string' is not assignable to type '() => boolean'.
-      Type 'string' is not assignable to type 'boolean'.
+      Signature '(): boolean' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'boolean'.
 tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not assignable to type 'Boolean'.
   Types of property 'valueOf' are incompatible.
     Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+      Signature '(): boolean' has no corresponding signature in '() => Object'
+        Type 'Object' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/booleanAssignment.ts (3 errors) ====
@@ -19,19 +22,22 @@ tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not a
 !!! error TS2322: Type 'number' is not assignable to type 'Boolean'.
 !!! error TS2322:   Types of property 'valueOf' are incompatible.
 !!! error TS2322:     Type '() => number' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'number' is not assignable to type 'boolean'.
+!!! error TS2322:       Signature '(): boolean' has no corresponding signature in '() => number'
+!!! error TS2322:         Type 'number' is not assignable to type 'boolean'.
     b = "a"; // Error
     ~
 !!! error TS2322: Type 'string' is not assignable to type 'Boolean'.
 !!! error TS2322:   Types of property 'valueOf' are incompatible.
 !!! error TS2322:     Type '() => string' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'string' is not assignable to type 'boolean'.
+!!! error TS2322:       Signature '(): boolean' has no corresponding signature in '() => string'
+!!! error TS2322:         Type 'string' is not assignable to type 'boolean'.
     b = {}; // Error
     ~
 !!! error TS2322: Type '{}' is not assignable to type 'Boolean'.
 !!! error TS2322:   Types of property 'valueOf' are incompatible.
 !!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:       Signature '(): boolean' has no corresponding signature in '() => Object'
+!!! error TS2322:         Type 'Object' is not assignable to type 'boolean'.
     
     var o = {};
     o = b; // OK
diff --git a/tests/baselines/reference/callConstructAssignment.errors.txt b/tests/baselines/reference/callConstructAssignment.errors.txt
index 42949cf585d..e52d8b1f063 100644
--- a/tests/baselines/reference/callConstructAssignment.errors.txt
+++ b/tests/baselines/reference/callConstructAssignment.errors.txt
@@ -1,5 +1,7 @@
 tests/cases/compiler/callConstructAssignment.ts(7,1): error TS2322: Type 'new () => any' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in 'new () => any'
 tests/cases/compiler/callConstructAssignment.ts(8,1): error TS2322: Type '() => void' is not assignable to type 'new () => any'.
+  Signature 'new (): any' has no corresponding signature in '() => void'
 
 
 ==== tests/cases/compiler/callConstructAssignment.ts (2 errors) ====
@@ -12,6 +14,8 @@ tests/cases/compiler/callConstructAssignment.ts(8,1): error TS2322: Type '() =>
     foo = bar; // error
     ~~~
 !!! error TS2322: Type 'new () => any' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'new () => any'
     bar = foo; // error
     ~~~
-!!! error TS2322: Type '() => void' is not assignable to type 'new () => any'.
\ No newline at end of file
+!!! error TS2322: Type '() => void' is not assignable to type 'new () => any'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '() => void'
\ No newline at end of file
diff --git a/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt b/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
index d6efdd66868..3e66787b54d 100644
--- a/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
+++ b/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts(57,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type '(x: number) => string' is not assignable to type '(x: number) => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): number' has no corresponding signature in '(x: number) => string'
+        Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts (1 errors) ====
@@ -66,7 +67,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x: number) => string' is not assignable to type '(x: number) => number'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: number): number' has no corresponding signature in '(x: number) => string'
+!!! error TS2430:         Type 'string' is not assignable to type 'number'.
             // N's
             a: (x: number) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt b/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
index 7e9d75b1b41..b3bdb17ea71 100644
--- a/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
+++ b/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
@@ -1,17 +1,20 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts(51,19): error TS2430: Interface 'I2<T, U>' incorrectly extends interface 'A'.
   Types of property 'a2' are incompatible.
     Type '(x: T) => U[]' is not assignable to type '(x: number) => string[]'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'T' is not assignable to type 'number'.
+      Signature '(x: number): string[]' has no corresponding signature in '(x: T) => U[]'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'T' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts(60,19): error TS2430: Interface 'I4' incorrectly extends interface 'A'.
   Types of property 'a8' are incompatible.
     Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-          Types of parameters 'arg2' and 'arg2' are incompatible.
-            Type '{ foo: number; }' is not assignable to type 'Base'.
-              Types of property 'foo' are incompatible.
-                Type 'number' is not assignable to type 'string'.
+      Signature '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+            Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+              Types of parameters 'arg2' and 'arg2' are incompatible.
+                Type '{ foo: number; }' is not assignable to type 'Base'.
+                  Types of property 'foo' are incompatible.
+                    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts (2 errors) ====
@@ -70,8 +73,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
 !!! error TS2430: Interface 'I2<T, U>' incorrectly extends interface 'A'.
 !!! error TS2430:   Types of property 'a2' are incompatible.
 !!! error TS2430:     Type '(x: T) => U[]' is not assignable to type '(x: number) => string[]'.
-!!! error TS2430:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2430:         Type 'T' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: number): string[]' has no corresponding signature in '(x: T) => U[]'
+!!! error TS2430:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2430:           Type 'T' is not assignable to type 'number'.
                 a2: (x: T) => U[]; // error, no contextual signature instantiation since I2.a2 is not generic
             }
     
@@ -85,12 +89,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
 !!! error TS2430: Interface 'I4' incorrectly extends interface 'A'.
 !!! error TS2430:   Types of property 'a8' are incompatible.
 !!! error TS2430:     Type '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-!!! error TS2430:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2430:         Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-!!! error TS2430:           Types of parameters 'arg2' and 'arg2' are incompatible.
-!!! error TS2430:             Type '{ foo: number; }' is not assignable to type 'Base'.
-!!! error TS2430:               Types of property 'foo' are incompatible.
-!!! error TS2430:                 Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in '<T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+!!! error TS2430:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2430:           Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+!!! error TS2430:             Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+!!! error TS2430:               Types of parameters 'arg2' and 'arg2' are incompatible.
+!!! error TS2430:                 Type '{ foo: number; }' is not assignable to type 'Base'.
+!!! error TS2430:                   Types of property 'foo' are incompatible.
+!!! error TS2430:                     Type 'number' is not assignable to type 'string'.
                 a8: <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U; // error, type mismatch
             }
     
diff --git a/tests/baselines/reference/castingTuple.errors.txt b/tests/baselines/reference/castingTuple.errors.txt
index 62a36c9c156..cdf40eeeff6 100644
--- a/tests/baselines/reference/castingTuple.errors.txt
+++ b/tests/baselines/reference/castingTuple.errors.txt
@@ -13,8 +13,9 @@ tests/cases/conformance/types/tuple/castingTuple.ts(30,5): error TS2403: Subsequ
 tests/cases/conformance/types/tuple/castingTuple.ts(30,14): error TS2352: Neither type '[number, string]' nor type 'number[]' is assignable to the other.
   Types of property 'pop' are incompatible.
     Type '() => number | string' is not assignable to type '() => number'.
-      Type 'number | string' is not assignable to type 'number'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | string'
+        Type 'number | string' is not assignable to type 'number'.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/tuple/castingTuple.ts(31,1): error TS2304: Cannot find name 't4'.
 
 
@@ -70,8 +71,9 @@ tests/cases/conformance/types/tuple/castingTuple.ts(31,1): error TS2304: Cannot
 !!! error TS2352: Neither type '[number, string]' nor type 'number[]' is assignable to the other.
 !!! error TS2352:   Types of property 'pop' are incompatible.
 !!! error TS2352:     Type '() => number | string' is not assignable to type '() => number'.
-!!! error TS2352:       Type 'number | string' is not assignable to type 'number'.
-!!! error TS2352:         Type 'string' is not assignable to type 'number'.
+!!! error TS2352:       Signature '(): number' has no corresponding signature in '() => number | string'
+!!! error TS2352:         Type 'number | string' is not assignable to type 'number'.
+!!! error TS2352:           Type 'string' is not assignable to type 'number'.
     t4[2] = 10;
     ~~
 !!! error TS2304: Cannot find name 't4'.
diff --git a/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.errors.txt b/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.errors.txt
index 181bfcc907d..579f6c47138 100644
--- a/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.errors.txt
+++ b/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.ts(19,59): error TS2345: Argument of type '(c: C) => B' is not assignable to parameter of type '(x: C) => C'.
-  Type 'B' is not assignable to type 'C'.
-    Property 'z' is missing in type 'B'.
+  Signature '(x: C): C' has no corresponding signature in '(c: C) => B'
+    Type 'B' is not assignable to type 'C'.
+      Property 'z' is missing in type 'B'.
 
 
 ==== tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter.ts (1 errors) ====
@@ -25,5 +26,6 @@ tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParamete
     (new Chain(new A)).then(a => new B).then(b => new C).then(c => new B).then(b => new A);
                                                               ~~~~~~~~~~
 !!! error TS2345: Argument of type '(c: C) => B' is not assignable to parameter of type '(x: C) => C'.
-!!! error TS2345:   Type 'B' is not assignable to type 'C'.
-!!! error TS2345:     Property 'z' is missing in type 'B'.
\ No newline at end of file
+!!! error TS2345:   Signature '(x: C): C' has no corresponding signature in '(c: C) => B'
+!!! error TS2345:     Type 'B' is not assignable to type 'C'.
+!!! error TS2345:       Property 'z' is missing in type 'B'.
\ No newline at end of file
diff --git a/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.errors.txt b/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.errors.txt
index 8f5924586df..1de7ead6e04 100644
--- a/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.errors.txt
+++ b/tests/baselines/reference/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.errors.txt
@@ -1,7 +1,9 @@
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.ts(7,43): error TS2345: Argument of type '(ss: S) => T' is not assignable to parameter of type '(x: S) => S'.
-  Type 'T' is not assignable to type 'S'.
+  Signature '(x: S): S' has no corresponding signature in '(ss: S) => T'
+    Type 'T' is not assignable to type 'S'.
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.ts(10,29): error TS2345: Argument of type '(ss: S) => T' is not assignable to parameter of type '(x: S) => S'.
-  Type 'T' is not assignable to type 'S'.
+  Signature '(x: S): S' has no corresponding signature in '(ss: S) => T'
+    Type 'T' is not assignable to type 'S'.
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.ts(32,9): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.ts(36,9): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParameter2.ts(37,9): error TS2322: Type 'string' is not assignable to type 'number'.
@@ -17,13 +19,15 @@ tests/cases/compiler/chainedCallsWithTypeParameterConstrainedToOtherTypeParamete
             (new Chain(t)).then(tt => s).then(ss => t);
                                               ~~~~~~~
 !!! error TS2345: Argument of type '(ss: S) => T' is not assignable to parameter of type '(x: S) => S'.
-!!! error TS2345:   Type 'T' is not assignable to type 'S'.
+!!! error TS2345:   Signature '(x: S): S' has no corresponding signature in '(ss: S) => T'
+!!! error TS2345:     Type 'T' is not assignable to type 'S'.
     
             // But error to try to climb up the chain
             (new Chain(s)).then(ss => t);
                                 ~~~~~~~
 !!! error TS2345: Argument of type '(ss: S) => T' is not assignable to parameter of type '(x: S) => S'.
-!!! error TS2345:   Type 'T' is not assignable to type 'S'.
+!!! error TS2345:   Signature '(x: S): S' has no corresponding signature in '(ss: S) => T'
+!!! error TS2345:     Type 'T' is not assignable to type 'S'.
     
             // Staying at T or S should be fine
             (new Chain(t)).then(tt => t).then(tt => t).then(tt => t);
diff --git a/tests/baselines/reference/classAbstractAssignabilityConstructorFunction.errors.txt b/tests/baselines/reference/classAbstractAssignabilityConstructorFunction.errors.txt
index c6c242396d8..5cb9a2e7f08 100644
--- a/tests/baselines/reference/classAbstractAssignabilityConstructorFunction.errors.txt
+++ b/tests/baselines/reference/classAbstractAssignabilityConstructorFunction.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAssignabilityConstructorFunction.ts(7,1): error TS2322: Type 'typeof A' is not assignable to type 'new () => A'.
   Cannot assign an abstract constructor type to a non-abstract constructor type.
 tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAssignabilityConstructorFunction.ts(8,1): error TS2322: Type 'string' is not assignable to type 'new () => A'.
+  Signature 'new (): A' has no corresponding signature in 'String'
 
 
 ==== tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractAssignabilityConstructorFunction.ts (2 errors) ====
@@ -16,4 +17,5 @@ tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbst
 !!! error TS2322:   Cannot assign an abstract constructor type to a non-abstract constructor type.
     AAA = "asdf";
     ~~~
-!!! error TS2322: Type 'string' is not assignable to type 'new () => A'.
\ No newline at end of file
+!!! error TS2322: Type 'string' is not assignable to type 'new () => A'.
+!!! error TS2322:   Signature 'new (): A' has no corresponding signature in 'String'
\ No newline at end of file
diff --git a/tests/baselines/reference/classSideInheritance3.errors.txt b/tests/baselines/reference/classSideInheritance3.errors.txt
index c845defa5b8..4d6a5a9b018 100644
--- a/tests/baselines/reference/classSideInheritance3.errors.txt
+++ b/tests/baselines/reference/classSideInheritance3.errors.txt
@@ -1,5 +1,7 @@
 tests/cases/compiler/classSideInheritance3.ts(16,5): error TS2322: Type 'typeof B' is not assignable to type 'typeof A'.
+  Signature 'new (x: string): A' has no corresponding signature in 'typeof B'
 tests/cases/compiler/classSideInheritance3.ts(17,5): error TS2322: Type 'typeof B' is not assignable to type 'new (x: string) => A'.
+  Signature 'new (x: string): A' has no corresponding signature in 'typeof B'
 
 
 ==== tests/cases/compiler/classSideInheritance3.ts (2 errors) ====
@@ -21,7 +23,9 @@ tests/cases/compiler/classSideInheritance3.ts(17,5): error TS2322: Type 'typeof
     var r1: typeof A = B; // error
         ~~
 !!! error TS2322: Type 'typeof B' is not assignable to type 'typeof A'.
+!!! error TS2322:   Signature 'new (x: string): A' has no corresponding signature in 'typeof B'
     var r2: new (x: string) => A = B; // error
         ~~
 !!! error TS2322: Type 'typeof B' is not assignable to type 'new (x: string) => A'.
+!!! error TS2322:   Signature 'new (x: string): A' has no corresponding signature in 'typeof B'
     var r3: typeof A = C; // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/conditionalOperatorWithoutIdenticalBCT.errors.txt b/tests/baselines/reference/conditionalOperatorWithoutIdenticalBCT.errors.txt
index 2fa13333058..867a044420d 100644
--- a/tests/baselines/reference/conditionalOperatorWithoutIdenticalBCT.errors.txt
+++ b/tests/baselines/reference/conditionalOperatorWithoutIdenticalBCT.errors.txt
@@ -6,13 +6,16 @@ tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithou
     Property 'propertyB' is missing in type 'A'.
 tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithoutIdenticalBCT.ts(19,5): error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => number'.
   Type '(n: X) => string' is not assignable to type '(t: X) => number'.
-    Type 'string' is not assignable to type 'number'.
+    Signature '(t: X): number' has no corresponding signature in '(n: X) => string'
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithoutIdenticalBCT.ts(20,5): error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => string'.
   Type '(m: X) => number' is not assignable to type '(t: X) => string'.
-    Type 'number' is not assignable to type 'string'.
+    Signature '(t: X): string' has no corresponding signature in '(m: X) => number'
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithoutIdenticalBCT.ts(21,5): error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => boolean'.
   Type '(m: X) => number' is not assignable to type '(t: X) => boolean'.
-    Type 'number' is not assignable to type 'boolean'.
+    Signature '(t: X): boolean' has no corresponding signature in '(m: X) => number'
+      Type 'number' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithoutIdenticalBCT.ts (5 errors) ====
@@ -46,16 +49,19 @@ tests/cases/conformance/expressions/conditonalOperator/conditionalOperatorWithou
         ~~~~~~~
 !!! error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => number'.
 !!! error TS2322:   Type '(n: X) => string' is not assignable to type '(t: X) => number'.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:     Signature '(t: X): number' has no corresponding signature in '(n: X) => string'
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     var result5: (t: X) => string = true ? (m) => m.propertyX1 : (n) => n.propertyX2;
         ~~~~~~~
 !!! error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => string'.
 !!! error TS2322:   Type '(m: X) => number' is not assignable to type '(t: X) => string'.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:     Signature '(t: X): string' has no corresponding signature in '(m: X) => number'
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
     var result6: (t: X) => boolean = true ? (m) => m.propertyX1 : (n) => n.propertyX2;
         ~~~~~~~
 !!! error TS2322: Type '((m: X) => number) | ((n: X) => string)' is not assignable to type '(t: X) => boolean'.
 !!! error TS2322:   Type '(m: X) => number' is not assignable to type '(t: X) => boolean'.
-!!! error TS2322:     Type 'number' is not assignable to type 'boolean'.
+!!! error TS2322:     Signature '(t: X): boolean' has no corresponding signature in '(m: X) => number'
+!!! error TS2322:       Type 'number' is not assignable to type 'boolean'.
     var result61: (t: X) => number| string = true ? (m) => m.propertyX1 : (n) => n.propertyX2;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt b/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
index 51278fc3f44..178239b729e 100644
--- a/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
+++ b/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance.ts(61,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type 'new (x: number) => string' is not assignable to type 'new (x: number) => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature 'new (x: number): number' has no corresponding signature in 'new (x: number) => string'
+        Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance.ts (1 errors) ====
@@ -70,7 +71,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new (x: number) => string' is not assignable to type 'new (x: number) => number'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature 'new (x: number): number' has no corresponding signature in 'new (x: number) => string'
+!!! error TS2430:         Type 'string' is not assignable to type 'number'.
             // N's
             a: new (x: number) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt b/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
index 8d6273804f7..5125fc27301 100644
--- a/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
+++ b/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
@@ -1,17 +1,20 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts(41,19): error TS2430: Interface 'I2<T, U>' incorrectly extends interface 'A'.
   Types of property 'a2' are incompatible.
     Type 'new (x: T) => U[]' is not assignable to type 'new (x: number) => string[]'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'T' is not assignable to type 'number'.
+      Signature 'new (x: number): string[]' has no corresponding signature in 'new (x: T) => U[]'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'T' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts(50,19): error TS2430: Interface 'I4' incorrectly extends interface 'A'.
   Types of property 'a8' are incompatible.
     Type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-          Types of parameters 'arg2' and 'arg2' are incompatible.
-            Type '{ foo: number; }' is not assignable to type 'Base'.
-              Types of property 'foo' are incompatible.
-                Type 'number' is not assignable to type 'string'.
+      Signature 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+            Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+              Types of parameters 'arg2' and 'arg2' are incompatible.
+                Type '{ foo: number; }' is not assignable to type 'Base'.
+                  Types of property 'foo' are incompatible.
+                    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts (2 errors) ====
@@ -60,8 +63,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
 !!! error TS2430: Interface 'I2<T, U>' incorrectly extends interface 'A'.
 !!! error TS2430:   Types of property 'a2' are incompatible.
 !!! error TS2430:     Type 'new (x: T) => U[]' is not assignable to type 'new (x: number) => string[]'.
-!!! error TS2430:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2430:         Type 'T' is not assignable to type 'number'.
+!!! error TS2430:       Signature 'new (x: number): string[]' has no corresponding signature in 'new (x: T) => U[]'
+!!! error TS2430:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2430:           Type 'T' is not assignable to type 'number'.
                 a2: new (x: T) => U[]; // error, no contextual signature instantiation since I2.a2 is not generic
             }
     
@@ -75,12 +79,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
 !!! error TS2430: Interface 'I4' incorrectly extends interface 'A'.
 !!! error TS2430:   Types of property 'a8' are incompatible.
 !!! error TS2430:     Type 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U' is not assignable to type 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived) => (r: Base) => Derived'.
-!!! error TS2430:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2430:         Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
-!!! error TS2430:           Types of parameters 'arg2' and 'arg2' are incompatible.
-!!! error TS2430:             Type '{ foo: number; }' is not assignable to type 'Base'.
-!!! error TS2430:               Types of property 'foo' are incompatible.
-!!! error TS2430:                 Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature 'new (x: (arg: Base) => Derived, y: (arg2: Base) => Derived): (r: Base) => Derived' has no corresponding signature in 'new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U'
+!!! error TS2430:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2430:           Type '(arg2: { foo: number; }) => any' is not assignable to type '(arg2: Base) => Derived'.
+!!! error TS2430:             Signature '(arg2: Base): Derived' has no corresponding signature in '(arg2: { foo: number; }) => any'
+!!! error TS2430:               Types of parameters 'arg2' and 'arg2' are incompatible.
+!!! error TS2430:                 Type '{ foo: number; }' is not assignable to type 'Base'.
+!!! error TS2430:                   Types of property 'foo' are incompatible.
+!!! error TS2430:                     Type 'number' is not assignable to type 'string'.
                 a8: new <T extends Base, U extends Derived>(x: (arg: T) => U, y: (arg2: { foo: number; }) => U) => (r: T) => U; // error, type mismatch
             }
     
diff --git a/tests/baselines/reference/constructorAsType.errors.txt b/tests/baselines/reference/constructorAsType.errors.txt
index b0d30295cde..3bf3dc688ed 100644
--- a/tests/baselines/reference/constructorAsType.errors.txt
+++ b/tests/baselines/reference/constructorAsType.errors.txt
@@ -1,10 +1,12 @@
 tests/cases/compiler/constructorAsType.ts(1,5): error TS2322: Type '() => { name: string; }' is not assignable to type 'new () => { name: string; }'.
+  Signature 'new (): { name: string; }' has no corresponding signature in '() => { name: string; }'
 
 
 ==== tests/cases/compiler/constructorAsType.ts (1 errors) ====
     var Person:new () => {name: string;} = function () {return {name:"joe"};};
         ~~~~~~
 !!! error TS2322: Type '() => { name: string; }' is not assignable to type 'new () => { name: string; }'.
+!!! error TS2322:   Signature 'new (): { name: string; }' has no corresponding signature in '() => { name: string; }'
     
     var Person2:{new() : {name:string;};};
     
diff --git a/tests/baselines/reference/contextualTypeWithTuple.errors.txt b/tests/baselines/reference/contextualTypeWithTuple.errors.txt
index e447ed62b39..249e96c8829 100644
--- a/tests/baselines/reference/contextualTypeWithTuple.errors.txt
+++ b/tests/baselines/reference/contextualTypeWithTuple.errors.txt
@@ -1,9 +1,10 @@
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(3,5): error TS2322: Type '[number, string, boolean]' is not assignable to type '[number, string]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string | boolean' is not assignable to type '() => number | string'.
-      Type 'number | string | boolean' is not assignable to type 'number | string'.
-        Type 'boolean' is not assignable to type 'number | string'.
-          Type 'boolean' is not assignable to type 'string'.
+      Signature '(): number | string' has no corresponding signature in '() => number | string | boolean'
+        Type 'number | string | boolean' is not assignable to type 'number | string'.
+          Type 'boolean' is not assignable to type 'number | string'.
+            Type 'boolean' is not assignable to type 'string'.
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(15,1): error TS2322: Type '[number, string, boolean]' is not assignable to type '[number, string]'.
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(18,1): error TS2322: Type '[{}, number]' is not assignable to type '[{ a: string; }, number]'.
   Types of property '0' are incompatible.
@@ -14,8 +15,9 @@ tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(19,1): error TS23
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(20,5): error TS2322: Type '[string, string, number]' is not assignable to type '[string, string]'.
   Types of property 'pop' are incompatible.
     Type '() => string | number' is not assignable to type '() => string'.
-      Type 'string | number' is not assignable to type 'string'.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => string | number'
+        Type 'string | number' is not assignable to type 'string'.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(24,1): error TS2322: Type '[C, string | number]' is not assignable to type '[C, string | number, D]'.
   Property '2' is missing in type '[C, string | number]'.
 tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(25,1): error TS2322: Type '[number, string | number]' is not assignable to type '[number, string]'.
@@ -32,9 +34,10 @@ tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(25,1): error TS23
 !!! error TS2322: Type '[number, string, boolean]' is not assignable to type '[number, string]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | string | boolean' is not assignable to type '() => number | string'.
-!!! error TS2322:       Type 'number | string | boolean' is not assignable to type 'number | string'.
-!!! error TS2322:         Type 'boolean' is not assignable to type 'number | string'.
-!!! error TS2322:           Type 'boolean' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): number | string' has no corresponding signature in '() => number | string | boolean'
+!!! error TS2322:         Type 'number | string | boolean' is not assignable to type 'number | string'.
+!!! error TS2322:           Type 'boolean' is not assignable to type 'number | string'.
+!!! error TS2322:             Type 'boolean' is not assignable to type 'string'.
     var numStrBoolTuple: [number, string, boolean] = [5, "foo", true];
     var objNumTuple: [{ a: string }, number] = [{ a: "world" }, 5];
     var strTupleTuple: [string, [number, {}]] = ["bar", [5, { x: 1, y: 1 }]];
@@ -66,8 +69,9 @@ tests/cases/conformance/types/tuple/contextualTypeWithTuple.ts(25,1): error TS23
 !!! error TS2322: Type '[string, string, number]' is not assignable to type '[string, string]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => string | number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'string | number' is not assignable to type 'string'.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => string | number'
+!!! error TS2322:         Type 'string | number' is not assignable to type 'string'.
+!!! error TS2322:           Type 'number' is not assignable to type 'string'.
     
     unionTuple = unionTuple1;
     unionTuple = unionTuple2;
diff --git a/tests/baselines/reference/contextualTypeWithUnionTypeObjectLiteral.errors.txt b/tests/baselines/reference/contextualTypeWithUnionTypeObjectLiteral.errors.txt
index 8be323f9af4..1e0865de8db 100644
--- a/tests/baselines/reference/contextualTypeWithUnionTypeObjectLiteral.errors.txt
+++ b/tests/baselines/reference/contextualTypeWithUnionTypeObjectLiteral.errors.txt
@@ -27,8 +27,9 @@ tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts(
   Type '{ commonMethodDifferentReturnType: (a: string, b: number) => string | number; }' is not assignable to type 'I21'.
     Types of property 'commonMethodDifferentReturnType' are incompatible.
       Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => number'.
-        Type 'string | number' is not assignable to type 'number'.
-          Type 'string' is not assignable to type 'number'.
+        Signature '(a: string, b: number): number' has no corresponding signature in '(a: string, b: number) => string | number'
+          Type 'string | number' is not assignable to type 'number'.
+            Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts (6 errors) ====
@@ -124,7 +125,8 @@ tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts(
 !!! error TS2322:   Type '{ commonMethodDifferentReturnType: (a: string, b: number) => string | number; }' is not assignable to type 'I21'.
 !!! error TS2322:     Types of property 'commonMethodDifferentReturnType' are incompatible.
 !!! error TS2322:       Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => number'.
-!!! error TS2322:         Type 'string | number' is not assignable to type 'number'.
-!!! error TS2322:           Type 'string' is not assignable to type 'number'.
+!!! error TS2322:         Signature '(a: string, b: number): number' has no corresponding signature in '(a: string, b: number) => string | number'
+!!! error TS2322:           Type 'string | number' is not assignable to type 'number'.
+!!! error TS2322:             Type 'string' is not assignable to type 'number'.
         commonMethodDifferentReturnType: (a, b) => strOrNumber,
     };
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTyping24.errors.txt b/tests/baselines/reference/contextualTyping24.errors.txt
index a172600e1c5..1d1fd191944 100644
--- a/tests/baselines/reference/contextualTyping24.errors.txt
+++ b/tests/baselines/reference/contextualTyping24.errors.txt
@@ -1,11 +1,15 @@
 tests/cases/compiler/contextualTyping24.ts(1,55): error TS2322: Type '(a: string) => number' is not assignable to type '(a: { (): number; (i: number): number; }) => number'.
-  Types of parameters 'a' and 'a' are incompatible.
-    Type 'string' is not assignable to type '{ (): number; (i: number): number; }'.
+  Signature '(a: { (): number; (i: number): number; }): number' has no corresponding signature in '(a: string) => number'
+    Types of parameters 'a' and 'a' are incompatible.
+      Type 'string' is not assignable to type '{ (): number; (i: number): number; }'.
+        Signature '(): number' has no corresponding signature in 'String'
 
 
 ==== tests/cases/compiler/contextualTyping24.ts (1 errors) ====
     var foo:(a:{():number; (i:number):number; })=>number; foo = function(a:string){return 5};
                                                           ~~~
 !!! error TS2322: Type '(a: string) => number' is not assignable to type '(a: { (): number; (i: number): number; }) => number'.
-!!! error TS2322:   Types of parameters 'a' and 'a' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type '{ (): number; (i: number): number; }'.
\ No newline at end of file
+!!! error TS2322:   Signature '(a: { (): number; (i: number): number; }): number' has no corresponding signature in '(a: string) => number'
+!!! error TS2322:     Types of parameters 'a' and 'a' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type '{ (): number; (i: number): number; }'.
+!!! error TS2322:         Signature '(): number' has no corresponding signature in 'String'
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTyping39.errors.txt b/tests/baselines/reference/contextualTyping39.errors.txt
index e43624fbead..3cf5e5aa9ff 100644
--- a/tests/baselines/reference/contextualTyping39.errors.txt
+++ b/tests/baselines/reference/contextualTyping39.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/contextualTyping39.ts(1,11): error TS2352: Neither type '() => string' nor type '() => number' is assignable to the other.
-  Type 'string' is not assignable to type 'number'.
+  Signature '(): number' has no corresponding signature in '() => string'
+    Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/contextualTyping39.ts (1 errors) ====
     var foo = <{ (): number; }> function() { return "err"; };
               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2352: Neither type '() => string' nor type '() => number' is assignable to the other.
-!!! error TS2352:   Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2352:   Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2352:     Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTyping41.errors.txt b/tests/baselines/reference/contextualTyping41.errors.txt
index 1ed6da1b782..a3e33f26ddd 100644
--- a/tests/baselines/reference/contextualTyping41.errors.txt
+++ b/tests/baselines/reference/contextualTyping41.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/contextualTyping41.ts(1,11): error TS2352: Neither type '() => string' nor type '{ (): number; (i: number): number; }' is assignable to the other.
-  Type 'string' is not assignable to type 'number'.
+  Signature '(): number' has no corresponding signature in '() => string'
+    Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/contextualTyping41.ts (1 errors) ====
     var foo = <{():number; (i:number):number; }> (function(){return "err";});
               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2352: Neither type '() => string' nor type '{ (): number; (i: number): number; }' is assignable to the other.
-!!! error TS2352:   Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2352:   Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2352:     Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTypingOfConditionalExpression2.errors.txt b/tests/baselines/reference/contextualTypingOfConditionalExpression2.errors.txt
index 08fe22c08e0..6fbf1b12967 100644
--- a/tests/baselines/reference/contextualTypingOfConditionalExpression2.errors.txt
+++ b/tests/baselines/reference/contextualTypingOfConditionalExpression2.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/compiler/contextualTypingOfConditionalExpression2.ts(11,5): error TS2322: Type '((a: C) => number) | ((b: number) => void)' is not assignable to type '(a: A) => void'.
   Type '(b: number) => void' is not assignable to type '(a: A) => void'.
-    Types of parameters 'b' and 'a' are incompatible.
-      Type 'number' is not assignable to type 'A'.
-        Property 'foo' is missing in type 'Number'.
+    Signature '(a: A): void' has no corresponding signature in '(b: number) => void'
+      Types of parameters 'b' and 'a' are incompatible.
+        Type 'number' is not assignable to type 'A'.
+          Property 'foo' is missing in type 'Number'.
 
 
 ==== tests/cases/compiler/contextualTypingOfConditionalExpression2.ts (1 errors) ====
@@ -20,7 +21,8 @@ tests/cases/compiler/contextualTypingOfConditionalExpression2.ts(11,5): error TS
         ~~
 !!! error TS2322: Type '((a: C) => number) | ((b: number) => void)' is not assignable to type '(a: A) => void'.
 !!! error TS2322:   Type '(b: number) => void' is not assignable to type '(a: A) => void'.
-!!! error TS2322:     Types of parameters 'b' and 'a' are incompatible.
-!!! error TS2322:       Type 'number' is not assignable to type 'A'.
-!!! error TS2322:         Property 'foo' is missing in type 'Number'.
+!!! error TS2322:     Signature '(a: A): void' has no corresponding signature in '(b: number) => void'
+!!! error TS2322:       Types of parameters 'b' and 'a' are incompatible.
+!!! error TS2322:         Type 'number' is not assignable to type 'A'.
+!!! error TS2322:           Property 'foo' is missing in type 'Number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/contextualTypingOfGenericFunctionTypedArguments1.errors.txt b/tests/baselines/reference/contextualTypingOfGenericFunctionTypedArguments1.errors.txt
index a11f0009016..530993a7e23 100644
--- a/tests/baselines/reference/contextualTypingOfGenericFunctionTypedArguments1.errors.txt
+++ b/tests/baselines/reference/contextualTypingOfGenericFunctionTypedArguments1.errors.txt
@@ -1,8 +1,10 @@
 tests/cases/compiler/contextualTypingOfGenericFunctionTypedArguments1.ts(16,32): error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => Date'.
-  Type 'string' is not assignable to type 'Date'.
-    Property 'toDateString' is missing in type 'String'.
+  Signature '(x: number): Date' has no corresponding signature in '(x: number) => string'
+    Type 'string' is not assignable to type 'Date'.
+      Property 'toDateString' is missing in type 'String'.
 tests/cases/compiler/contextualTypingOfGenericFunctionTypedArguments1.ts(17,32): error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => Date'.
-  Type 'string' is not assignable to type 'Date'.
+  Signature '(x: number): Date' has no corresponding signature in '(x: number) => string'
+    Type 'string' is not assignable to type 'Date'.
 
 
 ==== tests/cases/compiler/contextualTypingOfGenericFunctionTypedArguments1.ts (2 errors) ====
@@ -24,10 +26,12 @@ tests/cases/compiler/contextualTypingOfGenericFunctionTypedArguments1.ts(17,32):
     var r5 = _.forEach<number>(c2, f); 
                                    ~
 !!! error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => Date'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Date'.
-!!! error TS2345:     Property 'toDateString' is missing in type 'String'.
+!!! error TS2345:   Signature '(x: number): Date' has no corresponding signature in '(x: number) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Date'.
+!!! error TS2345:       Property 'toDateString' is missing in type 'String'.
     var r6 = _.forEach<number>(c2, (x) => { return x.toFixed() }); 
                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => Date'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Date'.
+!!! error TS2345:   Signature '(x: number): Date' has no corresponding signature in '(x: number) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Date'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/derivedClassTransitivity.errors.txt b/tests/baselines/reference/derivedClassTransitivity.errors.txt
index c6b620beb18..5f47163f13f 100644
--- a/tests/baselines/reference/derivedClassTransitivity.errors.txt
+++ b/tests/baselines/reference/derivedClassTransitivity.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity.ts(18,1): error TS2322: Type 'E' is not assignable to type 'C'.
   Types of property 'foo' are incompatible.
     Type '(x?: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x?: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity.ts (1 errors) ====
@@ -28,7 +29,8 @@ tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTra
 !!! error TS2322: Type 'E' is not assignable to type 'C'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x?: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x?: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     var r = c.foo(1);
     var r2 = e.foo('');
\ No newline at end of file
diff --git a/tests/baselines/reference/derivedClassTransitivity2.errors.txt b/tests/baselines/reference/derivedClassTransitivity2.errors.txt
index a8d2003c876..16aa54ef101 100644
--- a/tests/baselines/reference/derivedClassTransitivity2.errors.txt
+++ b/tests/baselines/reference/derivedClassTransitivity2.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity2.ts(18,1): error TS2322: Type 'E' is not assignable to type 'C'.
   Types of property 'foo' are incompatible.
     Type '(x: number, y?: string) => void' is not assignable to type '(x: number, y: number) => void'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number, y: number): void' has no corresponding signature in '(x: number, y?: string) => void'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity2.ts (1 errors) ====
@@ -28,7 +29,8 @@ tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTra
 !!! error TS2322: Type 'E' is not assignable to type 'C'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x: number, y?: string) => void' is not assignable to type '(x: number, y: number) => void'.
-!!! error TS2322:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number, y: number): void' has no corresponding signature in '(x: number, y?: string) => void'
+!!! error TS2322:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     var r = c.foo(1, 1);
     var r2 = e.foo(1, '');
\ No newline at end of file
diff --git a/tests/baselines/reference/derivedClassTransitivity3.errors.txt b/tests/baselines/reference/derivedClassTransitivity3.errors.txt
index 9d301255dfd..837c6db67c4 100644
--- a/tests/baselines/reference/derivedClassTransitivity3.errors.txt
+++ b/tests/baselines/reference/derivedClassTransitivity3.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity3.ts(18,1): error TS2322: Type 'E<string>' is not assignable to type 'C<string>'.
   Types of property 'foo' are incompatible.
     Type '(x: string, y?: number) => void' is not assignable to type '(x: string, y: string) => void'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x: string, y: string): void' has no corresponding signature in '(x: string, y?: number) => void'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity3.ts (1 errors) ====
@@ -28,7 +29,8 @@ tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTra
 !!! error TS2322: Type 'E<string>' is not assignable to type 'C<string>'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x: string, y?: number) => void' is not assignable to type '(x: string, y: string) => void'.
-!!! error TS2322:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(x: string, y: string): void' has no corresponding signature in '(x: string, y?: number) => void'
+!!! error TS2322:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2322:           Type 'number' is not assignable to type 'string'.
     var r = c.foo('', '');
     var r2 = e.foo('', 1);
\ No newline at end of file
diff --git a/tests/baselines/reference/derivedClassTransitivity4.errors.txt b/tests/baselines/reference/derivedClassTransitivity4.errors.txt
index c1a80e0a1d7..47d1d767fbd 100644
--- a/tests/baselines/reference/derivedClassTransitivity4.errors.txt
+++ b/tests/baselines/reference/derivedClassTransitivity4.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity4.ts(18,1): error TS2322: Type 'E' is not assignable to type 'C'.
   Types of property 'foo' are incompatible.
     Type '(x?: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x?: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTransitivity4.ts(19,9): error TS2445: Property 'foo' is protected and only accessible within class 'C' and its subclasses.
 
 
@@ -29,8 +30,9 @@ tests/cases/conformance/classes/members/inheritanceAndOverriding/derivedClassTra
 !!! error TS2322: Type 'E' is not assignable to type 'C'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x?: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x?: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     var r = c.foo(1);
             ~~~~~
 !!! error TS2445: Property 'foo' is protected and only accessible within class 'C' and its subclasses.
diff --git a/tests/baselines/reference/derivedInterfaceCallSignature.errors.txt b/tests/baselines/reference/derivedInterfaceCallSignature.errors.txt
index ae8fbe2ff5d..6f088a12a9a 100644
--- a/tests/baselines/reference/derivedInterfaceCallSignature.errors.txt
+++ b/tests/baselines/reference/derivedInterfaceCallSignature.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/derivedInterfaceCallSignature.ts(11,11): error TS2430: Interface 'D3SvgArea' incorrectly extends interface 'D3SvgPath'.
   Types of property 'x' are incompatible.
     Type '(x: (data: any, index?: number) => number) => D3SvgArea' is not assignable to type '() => (data: any, index?: number) => number'.
+      Signature '(): (data: any, index?: number) => number' has no corresponding signature in '(x: (data: any, index?: number) => number) => D3SvgArea'
 
 
 ==== tests/cases/compiler/derivedInterfaceCallSignature.ts (1 errors) ====
@@ -19,6 +20,7 @@ tests/cases/compiler/derivedInterfaceCallSignature.ts(11,11): error TS2430: Inte
 !!! error TS2430: Interface 'D3SvgArea' incorrectly extends interface 'D3SvgPath'.
 !!! error TS2430:   Types of property 'x' are incompatible.
 !!! error TS2430:     Type '(x: (data: any, index?: number) => number) => D3SvgArea' is not assignable to type '() => (data: any, index?: number) => number'.
+!!! error TS2430:       Signature '(): (data: any, index?: number) => number' has no corresponding signature in '(x: (data: any, index?: number) => number) => D3SvgArea'
         x(x: (data: any, index?: number) => number): D3SvgArea;
         y(y: (data: any, index?: number) => number): D3SvgArea;
         y0(): (data: any, index?: number) => number;
diff --git a/tests/baselines/reference/destructuringParameterDeclaration2.errors.txt b/tests/baselines/reference/destructuringParameterDeclaration2.errors.txt
index c8037255a32..a3311319960 100644
--- a/tests/baselines/reference/destructuringParameterDeclaration2.errors.txt
+++ b/tests/baselines/reference/destructuringParameterDeclaration2.errors.txt
@@ -5,10 +5,11 @@ tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(8,4): error TS2345: Argument of type '[number, number, string[][], string]' is not assignable to parameter of type '[number, number, string[][]]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string[][] | string' is not assignable to type '() => number | string[][]'.
-      Type 'number | string[][] | string' is not assignable to type 'number | string[][]'.
-        Type 'string' is not assignable to type 'number | string[][]'.
-          Type 'string' is not assignable to type 'string[][]'.
-            Property 'push' is missing in type 'String'.
+      Signature '(): number | string[][]' has no corresponding signature in '() => number | string[][] | string'
+        Type 'number | string[][] | string' is not assignable to type 'number | string[][]'.
+          Type 'string' is not assignable to type 'number | string[][]'.
+            Type 'string' is not assignable to type 'string[][]'.
+              Property 'push' is missing in type 'String'.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(16,8): error TS2371: A parameter initializer is only allowed in a function or constructor implementation.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(16,16): error TS2371: A parameter initializer is only allowed in a function or constructor implementation.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(23,14): error TS2345: Argument of type '{ x: string; y: boolean; }' is not assignable to parameter of type '{ x: number; y: any; }'.
@@ -47,9 +48,10 @@ tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(55,7): error TS2420: Class 'C4' incorrectly implements interface 'F2'.
   Types of property 'd4' are incompatible.
     Type '({x, y, c}: { x: any; y: any; c: any; }) => void' is not assignable to type '({x, y, z}?: { x: any; y: any; z: any; }) => any'.
-      Types of parameters '__0' and '__0' are incompatible.
-        Type '{ x: any; y: any; c: any; }' is not assignable to type '{ x: any; y: any; z: any; }'.
-          Property 'z' is missing in type '{ x: any; y: any; c: any; }'.
+      Signature '({x, y, z}?: { x: any; y: any; z: any; }): any' has no corresponding signature in '({x, y, c}: { x: any; y: any; c: any; }) => void'
+        Types of parameters '__0' and '__0' are incompatible.
+          Type '{ x: any; y: any; c: any; }' is not assignable to type '{ x: any; y: any; z: any; }'.
+            Property 'z' is missing in type '{ x: any; y: any; c: any; }'.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(56,8): error TS2463: A binding pattern parameter cannot be optional in an implementation signature.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(65,18): error TS2300: Duplicate identifier 'number'.
 tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(65,26): error TS2300: Duplicate identifier 'number'.
@@ -75,10 +77,11 @@ tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(
 !!! error TS2345: Argument of type '[number, number, string[][], string]' is not assignable to parameter of type '[number, number, string[][]]'.
 !!! error TS2345:   Types of property 'pop' are incompatible.
 !!! error TS2345:     Type '() => number | string[][] | string' is not assignable to type '() => number | string[][]'.
-!!! error TS2345:       Type 'number | string[][] | string' is not assignable to type 'number | string[][]'.
-!!! error TS2345:         Type 'string' is not assignable to type 'number | string[][]'.
-!!! error TS2345:           Type 'string' is not assignable to type 'string[][]'.
-!!! error TS2345:             Property 'push' is missing in type 'String'.
+!!! error TS2345:       Signature '(): number | string[][]' has no corresponding signature in '() => number | string[][] | string'
+!!! error TS2345:         Type 'number | string[][] | string' is not assignable to type 'number | string[][]'.
+!!! error TS2345:           Type 'string' is not assignable to type 'number | string[][]'.
+!!! error TS2345:             Type 'string' is not assignable to type 'string[][]'.
+!!! error TS2345:               Property 'push' is missing in type 'String'.
     
     
     // If the declaration includes an initializer expression (which is permitted only
@@ -179,9 +182,10 @@ tests/cases/conformance/es6/destructuring/destructuringParameterDeclaration2.ts(
 !!! error TS2420: Class 'C4' incorrectly implements interface 'F2'.
 !!! error TS2420:   Types of property 'd4' are incompatible.
 !!! error TS2420:     Type '({x, y, c}: { x: any; y: any; c: any; }) => void' is not assignable to type '({x, y, z}?: { x: any; y: any; z: any; }) => any'.
-!!! error TS2420:       Types of parameters '__0' and '__0' are incompatible.
-!!! error TS2420:         Type '{ x: any; y: any; c: any; }' is not assignable to type '{ x: any; y: any; z: any; }'.
-!!! error TS2420:           Property 'z' is missing in type '{ x: any; y: any; c: any; }'.
+!!! error TS2420:       Signature '({x, y, z}?: { x: any; y: any; z: any; }): any' has no corresponding signature in '({x, y, c}: { x: any; y: any; c: any; }) => void'
+!!! error TS2420:         Types of parameters '__0' and '__0' are incompatible.
+!!! error TS2420:           Type '{ x: any; y: any; c: any; }' is not assignable to type '{ x: any; y: any; z: any; }'.
+!!! error TS2420:             Property 'z' is missing in type '{ x: any; y: any; c: any; }'.
         d3([a, b, c]?) { }  // Error, binding pattern can't be optional in implementation signature
            ~~~~~~~~~~
 !!! error TS2463: A binding pattern parameter cannot be optional in an implementation signature.
diff --git a/tests/baselines/reference/enumAssignability.errors.txt b/tests/baselines/reference/enumAssignability.errors.txt
index 4a060ac3456..55e28ed97d9 100644
--- a/tests/baselines/reference/enumAssignability.errors.txt
+++ b/tests/baselines/reference/enumAssignability.errors.txt
@@ -6,9 +6,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
   Property 'toDateString' is missing in type 'Number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(33,9): error TS2322: Type 'E' is not assignable to type 'void'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(36,9): error TS2322: Type 'E' is not assignable to type '() => {}'.
+  Signature '(): {}' has no corresponding signature in 'Number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(37,9): error TS2322: Type 'E' is not assignable to type 'Function'.
   Property 'apply' is missing in type 'Number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(38,9): error TS2322: Type 'E' is not assignable to type '(x: number) => string'.
+  Signature '(x: number): string' has no corresponding signature in 'Number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(39,5): error TS2322: Type 'E' is not assignable to type 'C'.
   Property 'foo' is missing in type 'Number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(40,5): error TS2322: Type 'E' is not assignable to type 'I'.
@@ -18,6 +20,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(42,9): error TS2322: Type 'E' is not assignable to type '{ foo: string; }'.
   Property 'foo' is missing in type 'Number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(43,9): error TS2322: Type 'E' is not assignable to type '<T>(x: T) => T'.
+  Signature '<T>(x: T): T' has no corresponding signature in 'Number'
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(45,9): error TS2322: Type 'E' is not assignable to type 'String'.
   Property 'charAt' is missing in type 'Number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignability.ts(47,21): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -80,6 +83,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
         var j: () => {} = e;
             ~
 !!! error TS2322: Type 'E' is not assignable to type '() => {}'.
+!!! error TS2322:   Signature '(): {}' has no corresponding signature in 'Number'
         var k: Function = e;
             ~
 !!! error TS2322: Type 'E' is not assignable to type 'Function'.
@@ -87,6 +91,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
         var l: (x: number) => string = e;
             ~
 !!! error TS2322: Type 'E' is not assignable to type '(x: number) => string'.
+!!! error TS2322:   Signature '(x: number): string' has no corresponding signature in 'Number'
         ac = e;
         ~~
 !!! error TS2322: Type 'E' is not assignable to type 'C'.
@@ -106,6 +111,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
         var o: <T>(x: T) => T = e;
             ~
 !!! error TS2322: Type 'E' is not assignable to type '<T>(x: T) => T'.
+!!! error TS2322:   Signature '<T>(x: T): T' has no corresponding signature in 'Number'
         var p: Number = e;
         var q: String = e;
             ~
diff --git a/tests/baselines/reference/errorElaboration.errors.txt b/tests/baselines/reference/errorElaboration.errors.txt
index 94742d7d98b..42903f7fa04 100644
--- a/tests/baselines/reference/errorElaboration.errors.txt
+++ b/tests/baselines/reference/errorElaboration.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/compiler/errorElaboration.ts(12,5): error TS2345: Argument of type '() => Container<Ref<string>>' is not assignable to parameter of type '() => Container<Ref<number>>'.
-  Type 'Container<Ref<string>>' is not assignable to type 'Container<Ref<number>>'.
-    Type 'Ref<string>' is not assignable to type 'Ref<number>'.
-      Type 'string' is not assignable to type 'number'.
+  Signature '(): Container<Ref<number>>' has no corresponding signature in '() => Container<Ref<string>>'
+    Type 'Container<Ref<string>>' is not assignable to type 'Container<Ref<number>>'.
+      Type 'Ref<string>' is not assignable to type 'Ref<number>'.
+        Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/errorElaboration.ts (1 errors) ====
@@ -19,7 +20,8 @@ tests/cases/compiler/errorElaboration.ts(12,5): error TS2345: Argument of type '
     foo(a);
         ~
 !!! error TS2345: Argument of type '() => Container<Ref<string>>' is not assignable to parameter of type '() => Container<Ref<number>>'.
-!!! error TS2345:   Type 'Container<Ref<string>>' is not assignable to type 'Container<Ref<number>>'.
-!!! error TS2345:     Type 'Ref<string>' is not assignable to type 'Ref<number>'.
-!!! error TS2345:       Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(): Container<Ref<number>>' has no corresponding signature in '() => Container<Ref<string>>'
+!!! error TS2345:     Type 'Container<Ref<string>>' is not assignable to type 'Container<Ref<number>>'.
+!!! error TS2345:       Type 'Ref<string>' is not assignable to type 'Ref<number>'.
+!!! error TS2345:         Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt b/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
index 403e79b8742..8fbd4052bf9 100644
--- a/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
+++ b/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(1,5): error TS2322: Type '() => void' is not assignable to type '() => boolean'.
-  Type 'void' is not assignable to type 'boolean'.
+  Signature '(): boolean' has no corresponding signature in '() => void'
+    Type 'void' is not assignable to type 'boolean'.
 tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
@@ -7,7 +8,8 @@ tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355:
     var n1: () => boolean = function () { }; // expect an error here
         ~~
 !!! error TS2322: Type '() => void' is not assignable to type '() => boolean'.
-!!! error TS2322:   Type 'void' is not assignable to type 'boolean'.
+!!! error TS2322:   Signature '(): boolean' has no corresponding signature in '() => void'
+!!! error TS2322:     Type 'void' is not assignable to type 'boolean'.
     var n2: () => boolean = function ():boolean { }; // expect an error here
                                         ~~~~~~~
 !!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
diff --git a/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt b/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
index 12478442472..6cacd56eb17 100644
--- a/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
+++ b/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
@@ -16,21 +16,26 @@ tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAnd
   Types of property 'id' are incompatible.
     Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(46,5): error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: string) => number'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: string): number' has no corresponding signature in '(x: number) => boolean'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(47,5): error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: string) => number'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: string): number' has no corresponding signature in '(x: number) => boolean'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(48,5): error TS2322: Type '(x: string) => string' is not assignable to type '(x: string) => number'.
-  Type 'string' is not assignable to type 'number'.
+  Signature '(x: string): number' has no corresponding signature in '(x: string) => string'
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(50,5): error TS2322: Type 'typeof N' is not assignable to type 'typeof M'.
   Types of property 'A' are incompatible.
     Type 'typeof N.A' is not assignable to type 'typeof M.A'.
-      Type 'N.A' is not assignable to type 'M.A'.
-        Property 'name' is missing in type 'A'.
+      Signature 'new (): A' has no corresponding signature in 'typeof A'
+        Type 'N.A' is not assignable to type 'M.A'.
+          Property 'name' is missing in type 'A'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(51,5): error TS2322: Type 'N.A' is not assignable to type 'M.A'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(52,5): error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: number) => string'.
-  Type 'boolean' is not assignable to type 'string'.
+  Signature '(x: number): string' has no corresponding signature in '(x: number) => boolean'
+    Type 'boolean' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts (15 errors) ====
@@ -108,31 +113,36 @@ tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAnd
     var aFunction: typeof F = F2;
         ~~~~~~~~~
 !!! error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: string) => number'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: string): number' has no corresponding signature in '(x: number) => boolean'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
     var anOtherFunction: (x: string) => number = F2;
         ~~~~~~~~~~~~~~~
 !!! error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: string) => number'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: string): number' has no corresponding signature in '(x: number) => boolean'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
     var aLambda: typeof F = (x) => 'a string';
         ~~~~~~~
 !!! error TS2322: Type '(x: string) => string' is not assignable to type '(x: string) => number'.
-!!! error TS2322:   Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: string): number' has no corresponding signature in '(x: string) => string'
+!!! error TS2322:     Type 'string' is not assignable to type 'number'.
     
     var aModule: typeof M = N;
         ~~~~~~~
 !!! error TS2322: Type 'typeof N' is not assignable to type 'typeof M'.
 !!! error TS2322:   Types of property 'A' are incompatible.
 !!! error TS2322:     Type 'typeof N.A' is not assignable to type 'typeof M.A'.
-!!! error TS2322:       Type 'N.A' is not assignable to type 'M.A'.
-!!! error TS2322:         Property 'name' is missing in type 'A'.
+!!! error TS2322:       Signature 'new (): A' has no corresponding signature in 'typeof A'
+!!! error TS2322:         Type 'N.A' is not assignable to type 'M.A'.
+!!! error TS2322:           Property 'name' is missing in type 'A'.
     var aClassInModule: M.A = new N.A();
         ~~~~~~~~~~~~~~
 !!! error TS2322: Type 'N.A' is not assignable to type 'M.A'.
     var aFunctionInModule: typeof M.F2 = F2;
         ~~~~~~~~~~~~~~~~~
 !!! error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: number) => string'.
-!!! error TS2322:   Type 'boolean' is not assignable to type 'string'.
+!!! error TS2322:   Signature '(x: number): string' has no corresponding signature in '(x: number) => boolean'
+!!! error TS2322:     Type 'boolean' is not assignable to type 'string'.
     
     
\ No newline at end of file
diff --git a/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt b/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
index a44c95377dc..448851640cd 100644
--- a/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
+++ b/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(7,7): error TS2420: Class 'D' incorrectly implements interface 'C<number>'.
   Types of property 'bar' are incompatible.
     Type '() => string' is not assignable to type '() => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(12,5): error TS2322: Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(16,5): error TS2322: Type 'string' is not assignable to type 'number'.
 
@@ -18,7 +19,8 @@ tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(16,5): error TS2322:
 !!! error TS2420: Class 'D' incorrectly implements interface 'C<number>'.
 !!! error TS2420:   Types of property 'bar' are incompatible.
 !!! error TS2420:     Type '() => string' is not assignable to type '() => number'.
-!!! error TS2420:       Type 'string' is not assignable to type 'number'.
+!!! error TS2420:       Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2420:         Type 'string' is not assignable to type 'number'.
         baz() { }
     }
     
diff --git a/tests/baselines/reference/fixingTypeParametersRepeatedly2.errors.txt b/tests/baselines/reference/fixingTypeParametersRepeatedly2.errors.txt
index e56b58a268d..ca0c6bb9dca 100644
--- a/tests/baselines/reference/fixingTypeParametersRepeatedly2.errors.txt
+++ b/tests/baselines/reference/fixingTypeParametersRepeatedly2.errors.txt
@@ -1,8 +1,10 @@
 tests/cases/compiler/fixingTypeParametersRepeatedly2.ts(11,27): error TS2345: Argument of type '(d: Derived) => Base' is not assignable to parameter of type '(p: Derived) => Derived'.
-  Type 'Base' is not assignable to type 'Derived'.
-    Property 'toBase' is missing in type 'Base'.
+  Signature '(p: Derived): Derived' has no corresponding signature in '(d: Derived) => Base'
+    Type 'Base' is not assignable to type 'Derived'.
+      Property 'toBase' is missing in type 'Base'.
 tests/cases/compiler/fixingTypeParametersRepeatedly2.ts(17,27): error TS2345: Argument of type '(d: Derived) => Base' is not assignable to parameter of type '(p: Derived) => Derived'.
-  Type 'Base' is not assignable to type 'Derived'.
+  Signature '(p: Derived): Derived' has no corresponding signature in '(d: Derived) => Base'
+    Type 'Base' is not assignable to type 'Derived'.
 
 
 ==== tests/cases/compiler/fixingTypeParametersRepeatedly2.ts (2 errors) ====
@@ -19,8 +21,9 @@ tests/cases/compiler/fixingTypeParametersRepeatedly2.ts(17,27): error TS2345: Ar
     var result = foo(derived, d => d.toBase());
                               ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(d: Derived) => Base' is not assignable to parameter of type '(p: Derived) => Derived'.
-!!! error TS2345:   Type 'Base' is not assignable to type 'Derived'.
-!!! error TS2345:     Property 'toBase' is missing in type 'Base'.
+!!! error TS2345:   Signature '(p: Derived): Derived' has no corresponding signature in '(d: Derived) => Base'
+!!! error TS2345:     Type 'Base' is not assignable to type 'Derived'.
+!!! error TS2345:       Property 'toBase' is missing in type 'Base'.
     
     // bar should type check just like foo.
     // The same error should be observed in both cases.
@@ -29,4 +32,5 @@ tests/cases/compiler/fixingTypeParametersRepeatedly2.ts(17,27): error TS2345: Ar
     var result = bar(derived, d => d.toBase());
                               ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(d: Derived) => Base' is not assignable to parameter of type '(p: Derived) => Derived'.
-!!! error TS2345:   Type 'Base' is not assignable to type 'Derived'.
\ No newline at end of file
+!!! error TS2345:   Signature '(p: Derived): Derived' has no corresponding signature in '(d: Derived) => Base'
+!!! error TS2345:     Type 'Base' is not assignable to type 'Derived'.
\ No newline at end of file
diff --git a/tests/baselines/reference/for-of30.errors.txt b/tests/baselines/reference/for-of30.errors.txt
index 6434b5294d5..85c04fffdd0 100644
--- a/tests/baselines/reference/for-of30.errors.txt
+++ b/tests/baselines/reference/for-of30.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/conformance/es6/for-ofStatements/for-of30.ts(1,15): error TS2322: Type 'StringIterator' is not assignable to type 'Iterable<string>'.
   Types of property '[Symbol.iterator]' are incompatible.
     Type '() => StringIterator' is not assignable to type '() => Iterator<string>'.
-      Type 'StringIterator' is not assignable to type 'Iterator<string>'.
-        Types of property 'return' are incompatible.
-          Type 'number' is not assignable to type '(value?: any) => IteratorResult<string>'.
+      Signature '(): Iterator<string>' has no corresponding signature in '() => StringIterator'
+        Type 'StringIterator' is not assignable to type 'Iterator<string>'.
+          Types of property 'return' are incompatible.
+            Type 'number' is not assignable to type '(value?: any) => IteratorResult<string>'.
+              Signature '(value?: any): IteratorResult<string>' has no corresponding signature in 'Number'
 
 
 ==== tests/cases/conformance/es6/for-ofStatements/for-of30.ts (1 errors) ====
@@ -12,9 +14,11 @@ tests/cases/conformance/es6/for-ofStatements/for-of30.ts(1,15): error TS2322: Ty
 !!! error TS2322: Type 'StringIterator' is not assignable to type 'Iterable<string>'.
 !!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
 !!! error TS2322:     Type '() => StringIterator' is not assignable to type '() => Iterator<string>'.
-!!! error TS2322:       Type 'StringIterator' is not assignable to type 'Iterator<string>'.
-!!! error TS2322:         Types of property 'return' are incompatible.
-!!! error TS2322:           Type 'number' is not assignable to type '(value?: any) => IteratorResult<string>'.
+!!! error TS2322:       Signature '(): Iterator<string>' has no corresponding signature in '() => StringIterator'
+!!! error TS2322:         Type 'StringIterator' is not assignable to type 'Iterator<string>'.
+!!! error TS2322:           Types of property 'return' are incompatible.
+!!! error TS2322:             Type 'number' is not assignable to type '(value?: any) => IteratorResult<string>'.
+!!! error TS2322:               Signature '(value?: any): IteratorResult<string>' has no corresponding signature in 'Number'
     
     class StringIterator {
         next() {
diff --git a/tests/baselines/reference/for-of31.errors.txt b/tests/baselines/reference/for-of31.errors.txt
index 6d5f6e816be..111235d2f57 100644
--- a/tests/baselines/reference/for-of31.errors.txt
+++ b/tests/baselines/reference/for-of31.errors.txt
@@ -1,11 +1,13 @@
 tests/cases/conformance/es6/for-ofStatements/for-of31.ts(1,15): error TS2322: Type 'StringIterator' is not assignable to type 'Iterable<string>'.
   Types of property '[Symbol.iterator]' are incompatible.
     Type '() => StringIterator' is not assignable to type '() => Iterator<string>'.
-      Type 'StringIterator' is not assignable to type 'Iterator<string>'.
-        Types of property 'next' are incompatible.
-          Type '() => { value: string; }' is not assignable to type '(value?: any) => IteratorResult<string>'.
-            Type '{ value: string; }' is not assignable to type 'IteratorResult<string>'.
-              Property 'done' is missing in type '{ value: string; }'.
+      Signature '(): Iterator<string>' has no corresponding signature in '() => StringIterator'
+        Type 'StringIterator' is not assignable to type 'Iterator<string>'.
+          Types of property 'next' are incompatible.
+            Type '() => { value: string; }' is not assignable to type '(value?: any) => IteratorResult<string>'.
+              Signature '(value?: any): IteratorResult<string>' has no corresponding signature in '() => { value: string; }'
+                Type '{ value: string; }' is not assignable to type 'IteratorResult<string>'.
+                  Property 'done' is missing in type '{ value: string; }'.
 
 
 ==== tests/cases/conformance/es6/for-ofStatements/for-of31.ts (1 errors) ====
@@ -14,11 +16,13 @@ tests/cases/conformance/es6/for-ofStatements/for-of31.ts(1,15): error TS2322: Ty
 !!! error TS2322: Type 'StringIterator' is not assignable to type 'Iterable<string>'.
 !!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
 !!! error TS2322:     Type '() => StringIterator' is not assignable to type '() => Iterator<string>'.
-!!! error TS2322:       Type 'StringIterator' is not assignable to type 'Iterator<string>'.
-!!! error TS2322:         Types of property 'next' are incompatible.
-!!! error TS2322:           Type '() => { value: string; }' is not assignable to type '(value?: any) => IteratorResult<string>'.
-!!! error TS2322:             Type '{ value: string; }' is not assignable to type 'IteratorResult<string>'.
-!!! error TS2322:               Property 'done' is missing in type '{ value: string; }'.
+!!! error TS2322:       Signature '(): Iterator<string>' has no corresponding signature in '() => StringIterator'
+!!! error TS2322:         Type 'StringIterator' is not assignable to type 'Iterator<string>'.
+!!! error TS2322:           Types of property 'next' are incompatible.
+!!! error TS2322:             Type '() => { value: string; }' is not assignable to type '(value?: any) => IteratorResult<string>'.
+!!! error TS2322:               Signature '(value?: any): IteratorResult<string>' has no corresponding signature in '() => { value: string; }'
+!!! error TS2322:                 Type '{ value: string; }' is not assignable to type 'IteratorResult<string>'.
+!!! error TS2322:                   Property 'done' is missing in type '{ value: string; }'.
     
     class StringIterator {
         next() {
diff --git a/tests/baselines/reference/functionConstraintSatisfaction2.errors.txt b/tests/baselines/reference/functionConstraintSatisfaction2.errors.txt
index 871368da9fe..baf2af9794b 100644
--- a/tests/baselines/reference/functionConstraintSatisfaction2.errors.txt
+++ b/tests/baselines/reference/functionConstraintSatisfaction2.errors.txt
@@ -3,15 +3,23 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstrain
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(6,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(7,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(23,14): error TS2345: Argument of type 'Function' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'Function'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(24,15): error TS2345: Argument of type '(x: string[]) => string[]' is not assignable to parameter of type '(x: string) => string'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string[]' is not assignable to type 'string'.
+  Signature '(x: string): string' has no corresponding signature in '(x: string[]) => string[]'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string[]' is not assignable to type 'string'.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(25,15): error TS2345: Argument of type 'typeof C' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'typeof C'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(26,15): error TS2345: Argument of type 'new (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'new (x: string) => string'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(28,16): error TS2345: Argument of type '<U, V>(x: U, y: V) => U' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in '<U, V>(x: U, y: V) => U'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(29,16): error TS2345: Argument of type 'typeof C2' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'typeof C2'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(30,16): error TS2345: Argument of type 'new <T>(x: T) => T' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'new <T>(x: T) => T'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(34,16): error TS2345: Argument of type 'F2' is not assignable to parameter of type '(x: string) => string'.
+  Signature '(x: string): string' has no corresponding signature in 'F2'
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(36,38): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(37,10): error TS2345: Argument of type 'T' is not assignable to parameter of type '(x: string) => string'.
   Type '() => void' is not assignable to type '(x: string) => string'.
@@ -51,33 +59,41 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstrain
     var r = foo2(new Function());
                  ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type 'Function' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'Function'
     var r2 = foo2((x: string[]) => x);
                   ~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string[]) => string[]' is not assignable to parameter of type '(x: string) => string'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string[]' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in '(x: string[]) => string[]'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string[]' is not assignable to type 'string'.
     var r6 = foo2(C);
                   ~
 !!! error TS2345: Argument of type 'typeof C' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'typeof C'
     var r7 = foo2(b);
                   ~
 !!! error TS2345: Argument of type 'new (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'new (x: string) => string'
     var r8 = foo2(<U>(x: U) => x); // no error expected
     var r11 = foo2(<U, V>(x: U, y: V) => x);
                    ~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<U, V>(x: U, y: V) => U' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in '<U, V>(x: U, y: V) => U'
     var r13 = foo2(C2);
                    ~~
 !!! error TS2345: Argument of type 'typeof C2' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'typeof C2'
     var r14 = foo2(b2);
                    ~~
 !!! error TS2345: Argument of type 'new <T>(x: T) => T' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'new <T>(x: T) => T'
     
     interface F2 extends Function { foo: string; }
     var f2: F2;
     var r16 = foo2(f2);
                    ~~
 !!! error TS2345: Argument of type 'F2' is not assignable to parameter of type '(x: string) => string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in 'F2'
     
     function fff<T extends { (): void }, U extends T>(x: T, y: U) {
                                          ~~~~~~~~~~~
diff --git a/tests/baselines/reference/functionExpressionContextualTyping2.errors.txt b/tests/baselines/reference/functionExpressionContextualTyping2.errors.txt
index 6a3a7998f09..6ac40bcf2d9 100644
--- a/tests/baselines/reference/functionExpressionContextualTyping2.errors.txt
+++ b/tests/baselines/reference/functionExpressionContextualTyping2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping2.ts(11,1): error TS2322: Type '(foo: number, bar: string) => boolean' is not assignable to type '((n: number, s: string) => number) | ((n: number, s: string) => string)'.
   Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => string'.
-    Type 'boolean' is not assignable to type 'string'.
+    Signature '(n: number, s: string): string' has no corresponding signature in '(foo: number, bar: string) => boolean'
+      Type 'boolean' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping2.ts (1 errors) ====
@@ -18,4 +19,5 @@ tests/cases/conformance/expressions/contextualTyping/functionExpressionContextua
     ~~
 !!! error TS2322: Type '(foo: number, bar: string) => boolean' is not assignable to type '((n: number, s: string) => number) | ((n: number, s: string) => string)'.
 !!! error TS2322:   Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => string'.
-!!! error TS2322:     Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
+!!! error TS2322:     Signature '(n: number, s: string): string' has no corresponding signature in '(foo: number, bar: string) => boolean'
+!!! error TS2322:       Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/functionSignatureAssignmentCompat1.errors.txt b/tests/baselines/reference/functionSignatureAssignmentCompat1.errors.txt
index 86c4728dda2..86f89e94b04 100644
--- a/tests/baselines/reference/functionSignatureAssignmentCompat1.errors.txt
+++ b/tests/baselines/reference/functionSignatureAssignmentCompat1.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/functionSignatureAssignmentCompat1.ts(10,5): error TS2322: Type '(delimiter?: string) => ParserFunc' is not assignable to type 'ParserFunc'.
-  Types of parameters 'delimiter' and 'eventEmitter' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(eventEmitter: number, buffer: string): void' has no corresponding signature in '(delimiter?: string) => ParserFunc'
+    Types of parameters 'delimiter' and 'eventEmitter' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/functionSignatureAssignmentCompat1.ts (1 errors) ====
@@ -16,6 +17,7 @@ tests/cases/compiler/functionSignatureAssignmentCompat1.ts(10,5): error TS2322:
     var d: ParserFunc = parsers.readline; // not ok
         ~
 !!! error TS2322: Type '(delimiter?: string) => ParserFunc' is not assignable to type 'ParserFunc'.
-!!! error TS2322:   Types of parameters 'delimiter' and 'eventEmitter' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(eventEmitter: number, buffer: string): void' has no corresponding signature in '(delimiter?: string) => ParserFunc'
+!!! error TS2322:     Types of parameters 'delimiter' and 'eventEmitter' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     var e: ParserFunc = parsers.readline(); // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/generatorTypeCheck25.errors.txt b/tests/baselines/reference/generatorTypeCheck25.errors.txt
index 8d414c7c471..65aa94001b5 100644
--- a/tests/baselines/reference/generatorTypeCheck25.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck25.errors.txt
@@ -1,14 +1,17 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error TS2322: Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterable<Foo>'.
-  Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterable<Foo>'.
-    Types of property '[Symbol.iterator]' are incompatible.
-      Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterator<Foo>'.
-        Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterator<Foo>'.
-          Types of property 'next' are incompatible.
-            Type '(value?: any) => IteratorResult<Bar | Baz>' is not assignable to type '(value?: any) => IteratorResult<Foo>'.
-              Type 'IteratorResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo>'.
-                Type 'Bar | Baz' is not assignable to type 'Foo'.
-                  Type 'Baz' is not assignable to type 'Foo'.
-                    Property 'x' is missing in type 'Baz'.
+  Signature '(): Iterable<Foo>' has no corresponding signature in '() => IterableIterator<Bar | Baz>'
+    Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterable<Foo>'.
+      Types of property '[Symbol.iterator]' are incompatible.
+        Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterator<Foo>'.
+          Signature '(): Iterator<Foo>' has no corresponding signature in '() => IterableIterator<Bar | Baz>'
+            Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterator<Foo>'.
+              Types of property 'next' are incompatible.
+                Type '(value?: any) => IteratorResult<Bar | Baz>' is not assignable to type '(value?: any) => IteratorResult<Foo>'.
+                  Signature '(value?: any): IteratorResult<Foo>' has no corresponding signature in '(value?: any) => IteratorResult<Bar | Baz>'
+                    Type 'IteratorResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo>'.
+                      Type 'Bar | Baz' is not assignable to type 'Foo'.
+                        Type 'Baz' is not assignable to type 'Foo'.
+                          Property 'x' is missing in type 'Baz'.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts (1 errors) ====
@@ -18,16 +21,19 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error
     var g3: () => Iterable<Foo> = function* () {
         ~~
 !!! error TS2322: Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterable<Foo>'.
-!!! error TS2322:   Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterable<Foo>'.
-!!! error TS2322:     Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2322:       Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterator<Foo>'.
-!!! error TS2322:         Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterator<Foo>'.
-!!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(value?: any) => IteratorResult<Bar | Baz>' is not assignable to type '(value?: any) => IteratorResult<Foo>'.
-!!! error TS2322:               Type 'IteratorResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo>'.
-!!! error TS2322:                 Type 'Bar | Baz' is not assignable to type 'Foo'.
-!!! error TS2322:                   Type 'Baz' is not assignable to type 'Foo'.
-!!! error TS2322:                     Property 'x' is missing in type 'Baz'.
+!!! error TS2322:   Signature '(): Iterable<Foo>' has no corresponding signature in '() => IterableIterator<Bar | Baz>'
+!!! error TS2322:     Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterable<Foo>'.
+!!! error TS2322:       Types of property '[Symbol.iterator]' are incompatible.
+!!! error TS2322:         Type '() => IterableIterator<Bar | Baz>' is not assignable to type '() => Iterator<Foo>'.
+!!! error TS2322:           Signature '(): Iterator<Foo>' has no corresponding signature in '() => IterableIterator<Bar | Baz>'
+!!! error TS2322:             Type 'IterableIterator<Bar | Baz>' is not assignable to type 'Iterator<Foo>'.
+!!! error TS2322:               Types of property 'next' are incompatible.
+!!! error TS2322:                 Type '(value?: any) => IteratorResult<Bar | Baz>' is not assignable to type '(value?: any) => IteratorResult<Foo>'.
+!!! error TS2322:                   Signature '(value?: any): IteratorResult<Foo>' has no corresponding signature in '(value?: any) => IteratorResult<Bar | Baz>'
+!!! error TS2322:                     Type 'IteratorResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo>'.
+!!! error TS2322:                       Type 'Bar | Baz' is not assignable to type 'Foo'.
+!!! error TS2322:                         Type 'Baz' is not assignable to type 'Foo'.
+!!! error TS2322:                           Property 'x' is missing in type 'Baz'.
         yield;
         yield new Bar;
         yield new Baz;
diff --git a/tests/baselines/reference/generatorTypeCheck31.errors.txt b/tests/baselines/reference/generatorTypeCheck31.errors.txt
index a0336b464a4..9b77bb178c9 100644
--- a/tests/baselines/reference/generatorTypeCheck31.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck31.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck31.ts(2,11): error TS2322: Type 'IterableIterator<(x: any) => any>' is not assignable to type '() => Iterable<(x: string) => number>'.
+  Signature '(): Iterable<(x: string) => number>' has no corresponding signature in 'IterableIterator<(x: any) => any>'
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck31.ts (1 errors) ====
@@ -10,4 +11,5 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck31.ts(2,11): erro
         } ()
     ~~~~~~~~
 !!! error TS2322: Type 'IterableIterator<(x: any) => any>' is not assignable to type '() => Iterable<(x: string) => number>'.
+!!! error TS2322:   Signature '(): Iterable<(x: string) => number>' has no corresponding signature in 'IterableIterator<(x: any) => any>'
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/generatorTypeCheck8.errors.txt b/tests/baselines/reference/generatorTypeCheck8.errors.txt
index cedfecda60b..abd1db46bd1 100644
--- a/tests/baselines/reference/generatorTypeCheck8.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck8.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error TS2322: Type 'IterableIterator<string>' is not assignable to type 'BadGenerator'.
   Types of property 'next' are incompatible.
     Type '(value?: any) => IteratorResult<string>' is not assignable to type '(value?: any) => IteratorResult<number>'.
-      Type 'IteratorResult<string>' is not assignable to type 'IteratorResult<number>'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(value?: any): IteratorResult<number>' has no corresponding signature in '(value?: any) => IteratorResult<string>'
+        Type 'IteratorResult<string>' is not assignable to type 'IteratorResult<number>'.
+          Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts (1 errors) ====
@@ -12,5 +13,6 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error
 !!! error TS2322: Type 'IterableIterator<string>' is not assignable to type 'BadGenerator'.
 !!! error TS2322:   Types of property 'next' are incompatible.
 !!! error TS2322:     Type '(value?: any) => IteratorResult<string>' is not assignable to type '(value?: any) => IteratorResult<number>'.
-!!! error TS2322:       Type 'IteratorResult<string>' is not assignable to type 'IteratorResult<number>'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2322:       Signature '(value?: any): IteratorResult<number>' has no corresponding signature in '(value?: any) => IteratorResult<string>'
+!!! error TS2322:         Type 'IteratorResult<string>' is not assignable to type 'IteratorResult<number>'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/genericAssignmentCompatWithInterfaces1.errors.txt b/tests/baselines/reference/genericAssignmentCompatWithInterfaces1.errors.txt
index f335319cafd..3b52ed1e597 100644
--- a/tests/baselines/reference/genericAssignmentCompatWithInterfaces1.errors.txt
+++ b/tests/baselines/reference/genericAssignmentCompatWithInterfaces1.errors.txt
@@ -3,8 +3,9 @@ tests/cases/compiler/genericAssignmentCompatWithInterfaces1.ts(12,5): error TS23
     Type 'A<number>' is not assignable to type 'Comparable<string>'.
       Types of property 'compareTo' are incompatible.
         Type '(other: number) => number' is not assignable to type '(other: string) => number'.
-          Types of parameters 'other' and 'other' are incompatible.
-            Type 'number' is not assignable to type 'string'.
+          Signature '(other: string): number' has no corresponding signature in '(other: number) => number'
+            Types of parameters 'other' and 'other' are incompatible.
+              Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/genericAssignmentCompatWithInterfaces1.ts(13,5): error TS2322: Type '{ x: A<number>; }' is not assignable to type 'I<string>'.
   Types of property 'x' are incompatible.
     Type 'A<number>' is not assignable to type 'Comparable<string>'.
@@ -35,8 +36,9 @@ tests/cases/compiler/genericAssignmentCompatWithInterfaces1.ts(17,5): error TS23
 !!! error TS2322:     Type 'A<number>' is not assignable to type 'Comparable<string>'.
 !!! error TS2322:       Types of property 'compareTo' are incompatible.
 !!! error TS2322:         Type '(other: number) => number' is not assignable to type '(other: string) => number'.
-!!! error TS2322:           Types of parameters 'other' and 'other' are incompatible.
-!!! error TS2322:             Type 'number' is not assignable to type 'string'.
+!!! error TS2322:           Signature '(other: string): number' has no corresponding signature in '(other: number) => number'
+!!! error TS2322:             Types of parameters 'other' and 'other' are incompatible.
+!!! error TS2322:               Type 'number' is not assignable to type 'string'.
     var a2: I<string> = function (): { x: A<number> } {
         ~~
 !!! error TS2322: Type '{ x: A<number>; }' is not assignable to type 'I<string>'.
diff --git a/tests/baselines/reference/genericCallToOverloadedMethodWithOverloadedArguments.errors.txt b/tests/baselines/reference/genericCallToOverloadedMethodWithOverloadedArguments.errors.txt
index 428ebecf5b0..a6c6de7ffa7 100644
--- a/tests/baselines/reference/genericCallToOverloadedMethodWithOverloadedArguments.errors.txt
+++ b/tests/baselines/reference/genericCallToOverloadedMethodWithOverloadedArguments.errors.txt
@@ -1,15 +1,19 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverloadedMethodWithOverloadedArguments.ts(24,38): error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverloadedMethodWithOverloadedArguments.ts(53,38): error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverloadedMethodWithOverloadedArguments.ts(69,38): error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverloadedMethodWithOverloadedArguments.ts(85,38): error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; (b: boolean): Promise<boolean>; }' is not assignable to parameter of type '(x: number) => Promise<boolean>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<boolean>'.
-    Type 'number' is not assignable to type 'boolean'.
+  Signature '(x: number): Promise<boolean>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; (b: boolean): Promise<boolean>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<boolean>'.
+      Type 'number' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverloadedMethodWithOverloadedArguments.ts (4 errors) ====
@@ -39,8 +43,9 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverl
         var newPromise = numPromise.then(testFunction);
                                          ~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     }
     
     //////////////////////////////////////
@@ -72,8 +77,9 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverl
         var newPromise = numPromise.then(testFunction);
                                          ~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     }
     
     //////////////////////////////////////
@@ -92,8 +98,9 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverl
         var newPromise = numPromise.then(testFunction);
                                          ~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; }' is not assignable to parameter of type '(x: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: number): Promise<string>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     }
     
     //////////////////////////////////////
@@ -112,7 +119,8 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallToOverl
         var newPromise = numPromise.then(testFunction);
                                          ~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (n: number): Promise<number>; (s: string): Promise<string>; (b: boolean): Promise<boolean>; }' is not assignable to parameter of type '(x: number) => Promise<boolean>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<boolean>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'boolean'.
+!!! error TS2345:   Signature '(x: number): Promise<boolean>' has no corresponding signature in '{ (n: number): Promise<number>; (s: string): Promise<string>; (b: boolean): Promise<boolean>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<boolean>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'boolean'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/genericCallWithConstructorTypedArguments5.errors.txt b/tests/baselines/reference/genericCallWithConstructorTypedArguments5.errors.txt
index a014ef85b6c..451a9e2900d 100644
--- a/tests/baselines/reference/genericCallWithConstructorTypedArguments5.errors.txt
+++ b/tests/baselines/reference/genericCallWithConstructorTypedArguments5.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithConstructorTypedArguments5.ts(11,14): error TS2345: Argument of type '{ cb: new <T>(x: T, y: T) => string; }' is not assignable to parameter of type '{ cb: new (t: any) => string; }'.
   Types of property 'cb' are incompatible.
     Type 'new <T>(x: T, y: T) => string' is not assignable to type 'new (t: any) => string'.
+      Signature 'new (t: any): string' has no corresponding signature in 'new <T>(x: T, y: T) => string'
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithConstructorTypedArguments5.ts(13,14): error TS2345: Argument of type '{ cb: new (x: string, y: number) => string; }' is not assignable to parameter of type '{ cb: new (t: string) => string; }'.
   Types of property 'cb' are incompatible.
     Type 'new (x: string, y: number) => string' is not assignable to type 'new (t: string) => string'.
+      Signature 'new (t: string): string' has no corresponding signature in 'new (x: string, y: number) => string'
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithConstructorTypedArguments5.ts (2 errors) ====
@@ -22,12 +24,14 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithCon
 !!! error TS2345: Argument of type '{ cb: new <T>(x: T, y: T) => string; }' is not assignable to parameter of type '{ cb: new (t: any) => string; }'.
 !!! error TS2345:   Types of property 'cb' are incompatible.
 !!! error TS2345:     Type 'new <T>(x: T, y: T) => string' is not assignable to type 'new (t: any) => string'.
+!!! error TS2345:       Signature 'new (t: any): string' has no corresponding signature in 'new <T>(x: T, y: T) => string'
     var arg3: { cb: new (x: string, y: number) => string };
     var r3 = foo(arg3); // error
                  ~~~~
 !!! error TS2345: Argument of type '{ cb: new (x: string, y: number) => string; }' is not assignable to parameter of type '{ cb: new (t: string) => string; }'.
 !!! error TS2345:   Types of property 'cb' are incompatible.
 !!! error TS2345:     Type 'new (x: string, y: number) => string' is not assignable to type 'new (t: string) => string'.
+!!! error TS2345:       Signature 'new (t: string): string' has no corresponding signature in 'new (x: string, y: number) => string'
     
     function foo2<T, U>(arg: { cb: new(t: T, t2: T) => U }) {
         return new arg.cb(null, null);
diff --git a/tests/baselines/reference/genericCallWithGenericSignatureArguments2.errors.txt b/tests/baselines/reference/genericCallWithGenericSignatureArguments2.errors.txt
index c264058ad9f..4677d24164d 100644
--- a/tests/baselines/reference/genericCallWithGenericSignatureArguments2.errors.txt
+++ b/tests/baselines/reference/genericCallWithGenericSignatureArguments2.errors.txt
@@ -3,18 +3,21 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(15,21): error TS2345: Argument of type 'Date' is not assignable to parameter of type 'T'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(16,22): error TS2345: Argument of type 'number' is not assignable to parameter of type 'T'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(25,23): error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
-  Types of parameters 'a' and 'x' are incompatible.
-    Type 'T' is not assignable to type 'Date'.
-      Type 'RegExp' is not assignable to type 'Date'.
-        Property 'toDateString' is missing in type 'RegExp'.
+  Signature '(x: Date): Date' has no corresponding signature in '(a: T) => T'
+    Types of parameters 'a' and 'x' are incompatible.
+      Type 'T' is not assignable to type 'Date'.
+        Type 'RegExp' is not assignable to type 'Date'.
+          Property 'toDateString' is missing in type 'RegExp'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(37,36): error TS2345: Argument of type '(x: E) => F' is not assignable to parameter of type '(x: E) => E'.
-  Type 'F' is not assignable to type 'E'.
+  Signature '(x: E): E' has no corresponding signature in '(x: E) => F'
+    Type 'F' is not assignable to type 'E'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(50,21): error TS2345: Argument of type 'Date' is not assignable to parameter of type 'T'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(51,22): error TS2345: Argument of type 'number' is not assignable to parameter of type 'T'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(60,23): error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
-  Types of parameters 'a' and 'x' are incompatible.
-    Type 'T' is not assignable to type 'Date'.
-      Type 'RegExp' is not assignable to type 'Date'.
+  Signature '(x: Date): Date' has no corresponding signature in '(a: T) => T'
+    Types of parameters 'a' and 'x' are incompatible.
+      Type 'T' is not assignable to type 'Date'.
+        Type 'RegExp' is not assignable to type 'Date'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(67,51): error TS2304: Cannot find name 'U'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(67,57): error TS2304: Cannot find name 'U'.
 
@@ -54,10 +57,11 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
             var r7 = foo2((a: T) => a, (b: T) => b); // error
                           ~~~~~~~~~~~
 !!! error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
-!!! error TS2345:   Types of parameters 'a' and 'x' are incompatible.
-!!! error TS2345:     Type 'T' is not assignable to type 'Date'.
-!!! error TS2345:       Type 'RegExp' is not assignable to type 'Date'.
-!!! error TS2345:         Property 'toDateString' is missing in type 'RegExp'.
+!!! error TS2345:   Signature '(x: Date): Date' has no corresponding signature in '(a: T) => T'
+!!! error TS2345:     Types of parameters 'a' and 'x' are incompatible.
+!!! error TS2345:       Type 'T' is not assignable to type 'Date'.
+!!! error TS2345:         Type 'RegExp' is not assignable to type 'Date'.
+!!! error TS2345:           Property 'toDateString' is missing in type 'RegExp'.
             var r7b = foo2((a) => a, (b) => b); // valid, T is inferred to be Date
         }
     
@@ -72,7 +76,8 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
         var r7 = foo3(E.A, (x) => E.A, (x) => F.A); // error
                                        ~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: E) => F' is not assignable to parameter of type '(x: E) => E'.
-!!! error TS2345:   Type 'F' is not assignable to type 'E'.
+!!! error TS2345:   Signature '(x: E): E' has no corresponding signature in '(x: E) => F'
+!!! error TS2345:     Type 'F' is not assignable to type 'E'.
     }
     
     module TU {
@@ -102,9 +107,10 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
             var r7 = foo2((a: T) => a, (b: T) => b); 
                           ~~~~~~~~~~~
 !!! error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
-!!! error TS2345:   Types of parameters 'a' and 'x' are incompatible.
-!!! error TS2345:     Type 'T' is not assignable to type 'Date'.
-!!! error TS2345:       Type 'RegExp' is not assignable to type 'Date'.
+!!! error TS2345:   Signature '(x: Date): Date' has no corresponding signature in '(a: T) => T'
+!!! error TS2345:     Types of parameters 'a' and 'x' are incompatible.
+!!! error TS2345:       Type 'T' is not assignable to type 'Date'.
+!!! error TS2345:         Type 'RegExp' is not assignable to type 'Date'.
             var r7b = foo2((a) => a, (b) => b); 
         }
     
diff --git a/tests/baselines/reference/genericCallWithGenericSignatureArguments3.errors.txt b/tests/baselines/reference/genericCallWithGenericSignatureArguments3.errors.txt
index 87ae6b63855..cfee8e336b3 100644
--- a/tests/baselines/reference/genericCallWithGenericSignatureArguments3.errors.txt
+++ b/tests/baselines/reference/genericCallWithGenericSignatureArguments3.errors.txt
@@ -1,8 +1,10 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments3.ts(32,11): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate '(y: string) => string' is not a valid type argument because it is not a supertype of candidate '(a: string) => boolean'.
-    Type 'boolean' is not assignable to type 'string'.
+    Signature '(y: string): string' has no corresponding signature in '(a: string) => boolean'
+      Type 'boolean' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments3.ts(33,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate '(n: Object) => number' is not a valid type argument because it is not a supertype of candidate 'number'.
+    Signature '(n: Object): number' has no corresponding signature in 'Number'
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments3.ts (2 errors) ====
@@ -41,8 +43,10 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
               ~~~~
 !!! error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
 !!! error TS2453:   Type argument candidate '(y: string) => string' is not a valid type argument because it is not a supertype of candidate '(a: string) => boolean'.
-!!! error TS2453:     Type 'boolean' is not assignable to type 'string'.
+!!! error TS2453:     Signature '(y: string): string' has no corresponding signature in '(a: string) => boolean'
+!!! error TS2453:       Type 'boolean' is not assignable to type 'string'.
     var r12 = foo2(x, (a1: (y: string) => boolean) => (n: Object) => 1, (a2: (z: string) => boolean) => 2); // error
               ~~~~
 !!! error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
-!!! error TS2453:   Type argument candidate '(n: Object) => number' is not a valid type argument because it is not a supertype of candidate 'number'.
\ No newline at end of file
+!!! error TS2453:   Type argument candidate '(n: Object) => number' is not a valid type argument because it is not a supertype of candidate 'number'.
+!!! error TS2453:     Signature '(n: Object): number' has no corresponding signature in 'Number'
\ No newline at end of file
diff --git a/tests/baselines/reference/genericCallWithOverloadedConstructorTypedArguments2.errors.txt b/tests/baselines/reference/genericCallWithOverloadedConstructorTypedArguments2.errors.txt
index 80bcf12494a..230311a6642 100644
--- a/tests/baselines/reference/genericCallWithOverloadedConstructorTypedArguments2.errors.txt
+++ b/tests/baselines/reference/genericCallWithOverloadedConstructorTypedArguments2.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOverloadedConstructorTypedArguments2.ts(31,20): error TS2345: Argument of type 'new <T>(x: T, y: T) => string' is not assignable to parameter of type '{ new (x: any): string; new (x: any, y?: any): string; }'.
+  Signature 'new (x: any): string' has no corresponding signature in 'new <T>(x: T, y: T) => string'
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOverloadedConstructorTypedArguments2.ts (1 errors) ====
@@ -35,6 +36,7 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOve
         var r10 = foo6(b); // error
                        ~
 !!! error TS2345: Argument of type 'new <T>(x: T, y: T) => string' is not assignable to parameter of type '{ new (x: any): string; new (x: any, y?: any): string; }'.
+!!! error TS2345:   Signature 'new (x: any): string' has no corresponding signature in 'new <T>(x: T, y: T) => string'
     
         function foo7<T>(x:T, cb: { new(x: T): string; new(x: T, y?: T): string }) {
             return cb;
diff --git a/tests/baselines/reference/genericCallWithOverloadedFunctionTypedArguments2.errors.txt b/tests/baselines/reference/genericCallWithOverloadedFunctionTypedArguments2.errors.txt
index 32fe6a09344..0e2481feee8 100644
--- a/tests/baselines/reference/genericCallWithOverloadedFunctionTypedArguments2.errors.txt
+++ b/tests/baselines/reference/genericCallWithOverloadedFunctionTypedArguments2.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOverloadedFunctionTypedArguments2.ts(28,20): error TS2345: Argument of type '<T>(x: T, y: T) => string' is not assignable to parameter of type '{ (x: any): string; (x: any, y?: any): string; }'.
+  Signature '(x: any): string' has no corresponding signature in '<T>(x: T, y: T) => string'
 
 
 ==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOverloadedFunctionTypedArguments2.ts (1 errors) ====
@@ -32,6 +33,7 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithOve
         var r10 = foo6(<T>(x: T, y: T) => ''); // error
                        ~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, y: T) => string' is not assignable to parameter of type '{ (x: any): string; (x: any, y?: any): string; }'.
+!!! error TS2345:   Signature '(x: any): string' has no corresponding signature in '<T>(x: T, y: T) => string'
     
         function foo7<T>(x:T, cb: { (x: T): string; (x: T, y?: T): string }) {
             return cb;
diff --git a/tests/baselines/reference/genericCallWithTupleType.errors.txt b/tests/baselines/reference/genericCallWithTupleType.errors.txt
index d03f8d5e68a..518a4714247 100644
--- a/tests/baselines/reference/genericCallWithTupleType.errors.txt
+++ b/tests/baselines/reference/genericCallWithTupleType.errors.txt
@@ -1,9 +1,10 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(12,1): error TS2322: Type '[string, number, boolean, boolean]' is not assignable to type '[string, number]'.
   Types of property 'pop' are incompatible.
     Type '() => string | number | boolean' is not assignable to type '() => string | number'.
-      Type 'string | number | boolean' is not assignable to type 'string | number'.
-        Type 'boolean' is not assignable to type 'string | number'.
-          Type 'boolean' is not assignable to type 'number'.
+      Signature '(): string | number' has no corresponding signature in '() => string | number | boolean'
+        Type 'string | number | boolean' is not assignable to type 'string | number'.
+          Type 'boolean' is not assignable to type 'string | number'.
+            Type 'boolean' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(14,1): error TS2322: Type '{ a: string; }' is not assignable to type 'string | number'.
   Type '{ a: string; }' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTupleType.ts(22,1): error TS2322: Type '[number, string]' is not assignable to type '[string, number]'.
@@ -33,9 +34,10 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithTup
 !!! error TS2322: Type '[string, number, boolean, boolean]' is not assignable to type '[string, number]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => string | number | boolean' is not assignable to type '() => string | number'.
-!!! error TS2322:       Type 'string | number | boolean' is not assignable to type 'string | number'.
-!!! error TS2322:         Type 'boolean' is not assignable to type 'string | number'.
-!!! error TS2322:           Type 'boolean' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): string | number' has no corresponding signature in '() => string | number | boolean'
+!!! error TS2322:         Type 'string | number | boolean' is not assignable to type 'string | number'.
+!!! error TS2322:           Type 'boolean' is not assignable to type 'string | number'.
+!!! error TS2322:             Type 'boolean' is not assignable to type 'number'.
     var e3 = i1.tuple1[2];  // {}
     i1.tuple1[3] = { a: "string" };
     ~~~~~~~~~~~~
diff --git a/tests/baselines/reference/genericCombinators2.errors.txt b/tests/baselines/reference/genericCombinators2.errors.txt
index d590f1030c3..3dcc1b3c873 100644
--- a/tests/baselines/reference/genericCombinators2.errors.txt
+++ b/tests/baselines/reference/genericCombinators2.errors.txt
@@ -1,8 +1,10 @@
 tests/cases/compiler/genericCombinators2.ts(15,43): error TS2345: Argument of type '(x: number, y: string) => string' is not assignable to parameter of type '(x: number, y: string) => Date'.
-  Type 'string' is not assignable to type 'Date'.
-    Property 'toDateString' is missing in type 'String'.
+  Signature '(x: number, y: string): Date' has no corresponding signature in '(x: number, y: string) => string'
+    Type 'string' is not assignable to type 'Date'.
+      Property 'toDateString' is missing in type 'String'.
 tests/cases/compiler/genericCombinators2.ts(16,43): error TS2345: Argument of type '(x: number, y: string) => string' is not assignable to parameter of type '(x: number, y: string) => Date'.
-  Type 'string' is not assignable to type 'Date'.
+  Signature '(x: number, y: string): Date' has no corresponding signature in '(x: number, y: string) => string'
+    Type 'string' is not assignable to type 'Date'.
 
 
 ==== tests/cases/compiler/genericCombinators2.ts (2 errors) ====
@@ -23,9 +25,11 @@ tests/cases/compiler/genericCombinators2.ts(16,43): error TS2345: Argument of ty
     var r5a = _.map<number, string, Date>(c2, (x, y) => { return x.toFixed() });
                                               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y: string) => string' is not assignable to parameter of type '(x: number, y: string) => Date'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Date'.
-!!! error TS2345:     Property 'toDateString' is missing in type 'String'.
+!!! error TS2345:   Signature '(x: number, y: string): Date' has no corresponding signature in '(x: number, y: string) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Date'.
+!!! error TS2345:       Property 'toDateString' is missing in type 'String'.
     var r5b = _.map<number, string, Date>(c2, rf1);
                                               ~~~
 !!! error TS2345: Argument of type '(x: number, y: string) => string' is not assignable to parameter of type '(x: number, y: string) => Date'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Date'.
\ No newline at end of file
+!!! error TS2345:   Signature '(x: number, y: string): Date' has no corresponding signature in '(x: number, y: string) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Date'.
\ No newline at end of file
diff --git a/tests/baselines/reference/genericSpecializations3.errors.txt b/tests/baselines/reference/genericSpecializations3.errors.txt
index ccaa839f9d0..abfdf7a6640 100644
--- a/tests/baselines/reference/genericSpecializations3.errors.txt
+++ b/tests/baselines/reference/genericSpecializations3.errors.txt
@@ -1,18 +1,21 @@
 tests/cases/compiler/genericSpecializations3.ts(8,7): error TS2420: Class 'IntFooBad' incorrectly implements interface 'IFoo<number>'.
   Types of property 'foo' are incompatible.
     Type '(x: string) => string' is not assignable to type '(x: number) => number'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): number' has no corresponding signature in '(x: string) => string'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/genericSpecializations3.ts(28,1): error TS2322: Type 'StringFoo2' is not assignable to type 'IntFoo'.
   Types of property 'foo' are incompatible.
     Type '(x: string) => string' is not assignable to type '(x: number) => number'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): number' has no corresponding signature in '(x: string) => string'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/genericSpecializations3.ts(29,1): error TS2322: Type 'IntFoo' is not assignable to type 'StringFoo2'.
   Types of property 'foo' are incompatible.
     Type '(x: number) => number' is not assignable to type '(x: string) => string'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x: string): string' has no corresponding signature in '(x: number) => number'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/genericSpecializations3.ts (3 errors) ====
@@ -28,8 +31,9 @@ tests/cases/compiler/genericSpecializations3.ts(29,1): error TS2322: Type 'IntFo
 !!! error TS2420: Class 'IntFooBad' incorrectly implements interface 'IFoo<number>'.
 !!! error TS2420:   Types of property 'foo' are incompatible.
 !!! error TS2420:     Type '(x: string) => string' is not assignable to type '(x: number) => number'.
-!!! error TS2420:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2420:         Type 'string' is not assignable to type 'number'.
+!!! error TS2420:       Signature '(x: number): number' has no corresponding signature in '(x: string) => string'
+!!! error TS2420:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2420:           Type 'string' is not assignable to type 'number'.
         foo(x: string): string { return null; }
     }
     
@@ -54,15 +58,17 @@ tests/cases/compiler/genericSpecializations3.ts(29,1): error TS2322: Type 'IntFo
 !!! error TS2322: Type 'StringFoo2' is not assignable to type 'IntFoo'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x: string) => string' is not assignable to type '(x: number) => number'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): number' has no corresponding signature in '(x: string) => string'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     stringFoo2 = intFoo; // error
     ~~~~~~~~~~
 !!! error TS2322: Type 'IntFoo' is not assignable to type 'StringFoo2'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x: number) => number' is not assignable to type '(x: string) => string'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(x: string): string' has no corresponding signature in '(x: number) => number'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'number' is not assignable to type 'string'.
     
     
     class StringFoo3 implements IFoo<string> { // error
diff --git a/tests/baselines/reference/genericTypeAssertions2.errors.txt b/tests/baselines/reference/genericTypeAssertions2.errors.txt
index eda4c83646c..72bdf8a23a6 100644
--- a/tests/baselines/reference/genericTypeAssertions2.errors.txt
+++ b/tests/baselines/reference/genericTypeAssertions2.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/compiler/genericTypeAssertions2.ts(10,5): error TS2322: Type 'B<string>' is not assignable to type 'A<number>'.
   Types of property 'foo' are incompatible.
     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/genericTypeAssertions2.ts(11,5): error TS2322: Type 'A<number>' is not assignable to type 'B<number>'.
   Property 'bar' is missing in type 'A<number>'.
 tests/cases/compiler/genericTypeAssertions2.ts(13,21): error TS2352: Neither type 'undefined[]' nor type 'A<number>' is assignable to the other.
@@ -24,8 +25,9 @@ tests/cases/compiler/genericTypeAssertions2.ts(13,21): error TS2352: Neither typ
 !!! error TS2322: Type 'B<string>' is not assignable to type 'A<number>'.
 !!! error TS2322:   Types of property 'foo' are incompatible.
 !!! error TS2322:     Type '(x: string) => void' is not assignable to type '(x: number) => void'.
-!!! error TS2322:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(x: number): void' has no corresponding signature in '(x: string) => void'
+!!! error TS2322:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     var r3: B<number> = <A<number>>new B(); // error
         ~~
 !!! error TS2322: Type 'A<number>' is not assignable to type 'B<number>'.
diff --git a/tests/baselines/reference/genericTypeWithNonGenericBaseMisMatch.errors.txt b/tests/baselines/reference/genericTypeWithNonGenericBaseMisMatch.errors.txt
index 0fe15afcf33..d8bd78992a7 100644
--- a/tests/baselines/reference/genericTypeWithNonGenericBaseMisMatch.errors.txt
+++ b/tests/baselines/reference/genericTypeWithNonGenericBaseMisMatch.errors.txt
@@ -1,18 +1,20 @@
 tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(4,7): error TS2420: Class 'X<T>' incorrectly implements interface 'I'.
   Types of property 'f' are incompatible.
     Type '(a: T) => void' is not assignable to type '(a: { a: number; }) => void'.
-      Types of parameters 'a' and 'a' are incompatible.
-        Type 'T' is not assignable to type '{ a: number; }'.
-          Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-            Types of property 'a' are incompatible.
-              Type 'string' is not assignable to type 'number'.
+      Signature '(a: { a: number; }): void' has no corresponding signature in '(a: T) => void'
+        Types of parameters 'a' and 'a' are incompatible.
+          Type 'T' is not assignable to type '{ a: number; }'.
+            Type '{ a: string; }' is not assignable to type '{ a: number; }'.
+              Types of property 'a' are incompatible.
+                Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(8,5): error TS2322: Type 'X<{ a: string; }>' is not assignable to type 'I'.
   Types of property 'f' are incompatible.
     Type '(a: { a: string; }) => void' is not assignable to type '(a: { a: number; }) => void'.
-      Types of parameters 'a' and 'a' are incompatible.
-        Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-          Types of property 'a' are incompatible.
-            Type 'string' is not assignable to type 'number'.
+      Signature '(a: { a: number; }): void' has no corresponding signature in '(a: { a: string; }) => void'
+        Types of parameters 'a' and 'a' are incompatible.
+          Type '{ a: string; }' is not assignable to type '{ a: number; }'.
+            Types of property 'a' are incompatible.
+              Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts (2 errors) ====
@@ -24,11 +26,12 @@ tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(8,5): error TS2322
 !!! error TS2420: Class 'X<T>' incorrectly implements interface 'I'.
 !!! error TS2420:   Types of property 'f' are incompatible.
 !!! error TS2420:     Type '(a: T) => void' is not assignable to type '(a: { a: number; }) => void'.
-!!! error TS2420:       Types of parameters 'a' and 'a' are incompatible.
-!!! error TS2420:         Type 'T' is not assignable to type '{ a: number; }'.
-!!! error TS2420:           Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-!!! error TS2420:             Types of property 'a' are incompatible.
-!!! error TS2420:               Type 'string' is not assignable to type 'number'.
+!!! error TS2420:       Signature '(a: { a: number; }): void' has no corresponding signature in '(a: T) => void'
+!!! error TS2420:         Types of parameters 'a' and 'a' are incompatible.
+!!! error TS2420:           Type 'T' is not assignable to type '{ a: number; }'.
+!!! error TS2420:             Type '{ a: string; }' is not assignable to type '{ a: number; }'.
+!!! error TS2420:               Types of property 'a' are incompatible.
+!!! error TS2420:                 Type 'string' is not assignable to type 'number'.
     	f(a: T): void { }
     }
     var x = new X<{ a: string }>();
@@ -37,8 +40,9 @@ tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(8,5): error TS2322
 !!! error TS2322: Type 'X<{ a: string; }>' is not assignable to type 'I'.
 !!! error TS2322:   Types of property 'f' are incompatible.
 !!! error TS2322:     Type '(a: { a: string; }) => void' is not assignable to type '(a: { a: number; }) => void'.
-!!! error TS2322:       Types of parameters 'a' and 'a' are incompatible.
-!!! error TS2322:         Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-!!! error TS2322:           Types of property 'a' are incompatible.
-!!! error TS2322:             Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(a: { a: number; }): void' has no corresponding signature in '(a: { a: string; }) => void'
+!!! error TS2322:         Types of parameters 'a' and 'a' are incompatible.
+!!! error TS2322:           Type '{ a: string; }' is not assignable to type '{ a: number; }'.
+!!! error TS2322:             Types of property 'a' are incompatible.
+!!! error TS2322:               Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/generics4.errors.txt b/tests/baselines/reference/generics4.errors.txt
index 06bfa122901..93828628bd2 100644
--- a/tests/baselines/reference/generics4.errors.txt
+++ b/tests/baselines/reference/generics4.errors.txt
@@ -2,7 +2,8 @@ tests/cases/compiler/generics4.ts(7,1): error TS2322: Type 'C<Y>' is not assigna
   Type 'Y' is not assignable to type 'X'.
     Types of property 'f' are incompatible.
       Type '() => boolean' is not assignable to type '() => string'.
-        Type 'boolean' is not assignable to type 'string'.
+        Signature '(): string' has no corresponding signature in '() => boolean'
+          Type 'boolean' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/generics4.ts (1 errors) ====
@@ -18,4 +19,5 @@ tests/cases/compiler/generics4.ts(7,1): error TS2322: Type 'C<Y>' is not assigna
 !!! error TS2322:   Type 'Y' is not assignable to type 'X'.
 !!! error TS2322:     Types of property 'f' are incompatible.
 !!! error TS2322:       Type '() => boolean' is not assignable to type '() => string'.
-!!! error TS2322:         Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
+!!! error TS2322:         Signature '(): string' has no corresponding signature in '() => boolean'
+!!! error TS2322:           Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/implementGenericWithMismatchedTypes.errors.txt b/tests/baselines/reference/implementGenericWithMismatchedTypes.errors.txt
index 7a128b87764..9699ab80862 100644
--- a/tests/baselines/reference/implementGenericWithMismatchedTypes.errors.txt
+++ b/tests/baselines/reference/implementGenericWithMismatchedTypes.errors.txt
@@ -1,12 +1,14 @@
 tests/cases/compiler/implementGenericWithMismatchedTypes.ts(7,7): error TS2420: Class 'C<T>' incorrectly implements interface 'IFoo<T>'.
   Types of property 'foo' are incompatible.
     Type '(x: string) => number' is not assignable to type '(x: T) => T'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'T'.
+      Signature '(x: T): T' has no corresponding signature in '(x: string) => number'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'T'.
 tests/cases/compiler/implementGenericWithMismatchedTypes.ts(16,7): error TS2420: Class 'C2<T>' incorrectly implements interface 'IFoo2<T>'.
   Types of property 'foo' are incompatible.
     Type '<Tstring>(x: Tstring) => number' is not assignable to type '(x: T) => T'.
-      Type 'number' is not assignable to type 'T'.
+      Signature '(x: T): T' has no corresponding signature in '<Tstring>(x: Tstring) => number'
+        Type 'number' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/implementGenericWithMismatchedTypes.ts (2 errors) ====
@@ -21,8 +23,9 @@ tests/cases/compiler/implementGenericWithMismatchedTypes.ts(16,7): error TS2420:
 !!! error TS2420: Class 'C<T>' incorrectly implements interface 'IFoo<T>'.
 !!! error TS2420:   Types of property 'foo' are incompatible.
 !!! error TS2420:     Type '(x: string) => number' is not assignable to type '(x: T) => T'.
-!!! error TS2420:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2420:         Type 'string' is not assignable to type 'T'.
+!!! error TS2420:       Signature '(x: T): T' has no corresponding signature in '(x: string) => number'
+!!! error TS2420:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2420:           Type 'string' is not assignable to type 'T'.
         foo(x: string): number {
             return null;
         }
@@ -36,7 +39,8 @@ tests/cases/compiler/implementGenericWithMismatchedTypes.ts(16,7): error TS2420:
 !!! error TS2420: Class 'C2<T>' incorrectly implements interface 'IFoo2<T>'.
 !!! error TS2420:   Types of property 'foo' are incompatible.
 !!! error TS2420:     Type '<Tstring>(x: Tstring) => number' is not assignable to type '(x: T) => T'.
-!!! error TS2420:       Type 'number' is not assignable to type 'T'.
+!!! error TS2420:       Signature '(x: T): T' has no corresponding signature in '<Tstring>(x: Tstring) => number'
+!!! error TS2420:         Type 'number' is not assignable to type 'T'.
         foo<Tstring>(x: Tstring): number {
             return null;
         }
diff --git a/tests/baselines/reference/incompatibleTypes.errors.txt b/tests/baselines/reference/incompatibleTypes.errors.txt
index e612600a7f8..eddd01cc979 100644
--- a/tests/baselines/reference/incompatibleTypes.errors.txt
+++ b/tests/baselines/reference/incompatibleTypes.errors.txt
@@ -1,12 +1,14 @@
 tests/cases/compiler/incompatibleTypes.ts(5,7): error TS2420: Class 'C1' incorrectly implements interface 'IFoo1'.
   Types of property 'p1' are incompatible.
     Type '() => string' is not assignable to type '() => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/incompatibleTypes.ts(15,7): error TS2420: Class 'C2' incorrectly implements interface 'IFoo2'.
   Types of property 'p1' are incompatible.
     Type '(n: number) => number' is not assignable to type '(s: string) => number'.
-      Types of parameters 'n' and 's' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(s: string): number' has no corresponding signature in '(n: number) => number'
+        Types of parameters 'n' and 's' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/incompatibleTypes.ts(25,7): error TS2420: Class 'C3' incorrectly implements interface 'IFoo3'.
   Types of property 'p1' are incompatible.
     Type 'number' is not assignable to type 'string'.
@@ -17,13 +19,16 @@ tests/cases/compiler/incompatibleTypes.ts(33,7): error TS2420: Class 'C4' incorr
 tests/cases/compiler/incompatibleTypes.ts(42,5): error TS2345: Argument of type 'C1' is not assignable to parameter of type 'IFoo2'.
   Types of property 'p1' are incompatible.
     Type '() => string' is not assignable to type '(s: string) => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(s: string): number' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/incompatibleTypes.ts(49,7): error TS2345: Argument of type '{ e: number; f: number; }' is not assignable to parameter of type '{ c: { b: string; }; d: string; }'.
   Object literal may only specify known properties, and 'e' does not exist in type '{ c: { b: string; }; d: string; }'.
 tests/cases/compiler/incompatibleTypes.ts(66,47): error TS2322: Type '{ e: number; f: number; }' is not assignable to type '{ a: { a: string; }; b: string; }'.
   Object literal may only specify known properties, and 'e' does not exist in type '{ a: { a: string; }; b: string; }'.
 tests/cases/compiler/incompatibleTypes.ts(72,5): error TS2322: Type 'number' is not assignable to type '() => string'.
+  Signature '(): string' has no corresponding signature in 'Number'
 tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) => number' is not assignable to type '() => any'.
+  Signature '(): any' has no corresponding signature in '(a: any) => number'
 
 
 ==== tests/cases/compiler/incompatibleTypes.ts (9 errors) ====
@@ -36,7 +41,8 @@ tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) =>
 !!! error TS2420: Class 'C1' incorrectly implements interface 'IFoo1'.
 !!! error TS2420:   Types of property 'p1' are incompatible.
 !!! error TS2420:     Type '() => string' is not assignable to type '() => number'.
-!!! error TS2420:       Type 'string' is not assignable to type 'number'.
+!!! error TS2420:       Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2420:         Type 'string' is not assignable to type 'number'.
         public p1() {
             return "s";
         }
@@ -51,8 +57,9 @@ tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) =>
 !!! error TS2420: Class 'C2' incorrectly implements interface 'IFoo2'.
 !!! error TS2420:   Types of property 'p1' are incompatible.
 !!! error TS2420:     Type '(n: number) => number' is not assignable to type '(s: string) => number'.
-!!! error TS2420:       Types of parameters 'n' and 's' are incompatible.
-!!! error TS2420:         Type 'number' is not assignable to type 'string'.
+!!! error TS2420:       Signature '(s: string): number' has no corresponding signature in '(n: number) => number'
+!!! error TS2420:         Types of parameters 'n' and 's' are incompatible.
+!!! error TS2420:           Type 'number' is not assignable to type 'string'.
         public p1(n:number) {
             return 0;
         }
@@ -93,7 +100,8 @@ tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) =>
 !!! error TS2345: Argument of type 'C1' is not assignable to parameter of type 'IFoo2'.
 !!! error TS2345:   Types of property 'p1' are incompatible.
 !!! error TS2345:     Type '() => string' is not assignable to type '(s: string) => number'.
-!!! error TS2345:       Type 'string' is not assignable to type 'number'.
+!!! error TS2345:       Signature '(s: string): number' has no corresponding signature in '() => string'
+!!! error TS2345:         Type 'string' is not assignable to type 'number'.
     
     
     function of1(n: { a: { a: string; }; b: string; }): number;
@@ -132,8 +140,10 @@ tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) =>
     var i1c1: { (): string; } = 5;
         ~~~~
 !!! error TS2322: Type 'number' is not assignable to type '() => string'.
+!!! error TS2322:   Signature '(): string' has no corresponding signature in 'Number'
     
     var fp1: () =>any = a => 0;
         ~~~
 !!! error TS2322: Type '(a: any) => number' is not assignable to type '() => any'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in '(a: any) => number'
     
\ No newline at end of file
diff --git a/tests/baselines/reference/inheritance.errors.txt b/tests/baselines/reference/inheritance.errors.txt
index c667e8b001e..eef06b4c961 100644
--- a/tests/baselines/reference/inheritance.errors.txt
+++ b/tests/baselines/reference/inheritance.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/inheritance.ts(30,7): error TS2415: Class 'Baad' incorrectly extends base class 'Good'.
   Types of property 'g' are incompatible.
     Type '(n: number) => number' is not assignable to type '() => number'.
+      Signature '(): number' has no corresponding signature in '(n: number) => number'
 tests/cases/compiler/inheritance.ts(31,12): error TS2425: Class 'Good' defines instance member property 'f', but extended class 'Baad' defines it as instance member function.
 
 
@@ -39,6 +40,7 @@ tests/cases/compiler/inheritance.ts(31,12): error TS2425: Class 'Good' defines i
 !!! error TS2415: Class 'Baad' incorrectly extends base class 'Good'.
 !!! error TS2415:   Types of property 'g' are incompatible.
 !!! error TS2415:     Type '(n: number) => number' is not assignable to type '() => number'.
+!!! error TS2415:       Signature '(): number' has no corresponding signature in '(n: number) => number'
         public f(): number { return 0; }
                ~
 !!! error TS2425: Class 'Good' defines instance member property 'f', but extended class 'Baad' defines it as instance member function.
diff --git a/tests/baselines/reference/inheritanceMemberAccessorOverridingMethod.errors.txt b/tests/baselines/reference/inheritanceMemberAccessorOverridingMethod.errors.txt
index 6fde83e08b0..25dd3c2ef3b 100644
--- a/tests/baselines/reference/inheritanceMemberAccessorOverridingMethod.errors.txt
+++ b/tests/baselines/reference/inheritanceMemberAccessorOverridingMethod.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/inheritanceMemberAccessorOverridingMethod.ts(7,7): error TS2415: Class 'b' incorrectly extends base class 'a'.
   Types of property 'x' are incompatible.
     Type 'string' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in 'String'
 tests/cases/compiler/inheritanceMemberAccessorOverridingMethod.ts(8,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/compiler/inheritanceMemberAccessorOverridingMethod.ts(8,9): error TS2423: Class 'a' defines instance member function 'x', but extended class 'b' defines it as instance member accessor.
 tests/cases/compiler/inheritanceMemberAccessorOverridingMethod.ts(11,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
@@ -18,6 +19,7 @@ tests/cases/compiler/inheritanceMemberAccessorOverridingMethod.ts(11,9): error T
 !!! error TS2415: Class 'b' incorrectly extends base class 'a'.
 !!! error TS2415:   Types of property 'x' are incompatible.
 !!! error TS2415:     Type 'string' is not assignable to type '() => string'.
+!!! error TS2415:       Signature '(): string' has no corresponding signature in 'String'
         get x() {
             ~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
diff --git a/tests/baselines/reference/inheritanceStaticAccessorOverridingMethod.errors.txt b/tests/baselines/reference/inheritanceStaticAccessorOverridingMethod.errors.txt
index 38b1ed61fac..646047f8633 100644
--- a/tests/baselines/reference/inheritanceStaticAccessorOverridingMethod.errors.txt
+++ b/tests/baselines/reference/inheritanceStaticAccessorOverridingMethod.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/inheritanceStaticAccessorOverridingMethod.ts(7,7): error TS2417: Class static side 'typeof b' incorrectly extends base class static side 'typeof a'.
   Types of property 'x' are incompatible.
     Type 'string' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in 'String'
 tests/cases/compiler/inheritanceStaticAccessorOverridingMethod.ts(8,16): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/compiler/inheritanceStaticAccessorOverridingMethod.ts(11,16): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 
@@ -17,6 +18,7 @@ tests/cases/compiler/inheritanceStaticAccessorOverridingMethod.ts(11,16): error
 !!! error TS2417: Class static side 'typeof b' incorrectly extends base class static side 'typeof a'.
 !!! error TS2417:   Types of property 'x' are incompatible.
 !!! error TS2417:     Type 'string' is not assignable to type '() => string'.
+!!! error TS2417:       Signature '(): string' has no corresponding signature in 'String'
         static get x() {
                    ~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
diff --git a/tests/baselines/reference/inheritanceStaticPropertyOverridingMethod.errors.txt b/tests/baselines/reference/inheritanceStaticPropertyOverridingMethod.errors.txt
index 22748fda783..5e983c0d806 100644
--- a/tests/baselines/reference/inheritanceStaticPropertyOverridingMethod.errors.txt
+++ b/tests/baselines/reference/inheritanceStaticPropertyOverridingMethod.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/inheritanceStaticPropertyOverridingMethod.ts(7,7): error TS2417: Class static side 'typeof b' incorrectly extends base class static side 'typeof a'.
   Types of property 'x' are incompatible.
     Type 'string' is not assignable to type '() => string'.
+      Signature '(): string' has no corresponding signature in 'String'
 
 
 ==== tests/cases/compiler/inheritanceStaticPropertyOverridingMethod.ts (1 errors) ====
@@ -15,5 +16,6 @@ tests/cases/compiler/inheritanceStaticPropertyOverridingMethod.ts(7,7): error TS
 !!! error TS2417: Class static side 'typeof b' incorrectly extends base class static side 'typeof a'.
 !!! error TS2417:   Types of property 'x' are incompatible.
 !!! error TS2417:     Type 'string' is not assignable to type '() => string'.
+!!! error TS2417:       Signature '(): string' has no corresponding signature in 'String'
         static x: string;
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt b/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
index 0b7e00d95ce..6c67e28e2f9 100644
--- a/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
+++ b/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/compiler/inheritedModuleMembersForClodule.ts(7,7): error TS2417: Class static side 'typeof D' incorrectly extends base class static side 'typeof C'.
   Types of property 'foo' are incompatible.
     Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => number'
+        Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/inheritedModuleMembersForClodule.ts (1 errors) ====
@@ -16,7 +17,8 @@ tests/cases/compiler/inheritedModuleMembersForClodule.ts(7,7): error TS2417: Cla
 !!! error TS2417: Class static side 'typeof D' incorrectly extends base class static side 'typeof C'.
 !!! error TS2417:   Types of property 'foo' are incompatible.
 !!! error TS2417:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2417:       Type 'number' is not assignable to type 'string'.
+!!! error TS2417:       Signature '(): string' has no corresponding signature in '() => number'
+!!! error TS2417:         Type 'number' is not assignable to type 'string'.
     }
     
     module D {
diff --git a/tests/baselines/reference/instanceMemberAssignsToClassPrototype.errors.txt b/tests/baselines/reference/instanceMemberAssignsToClassPrototype.errors.txt
index 080316f8daf..cca68d4ef96 100644
--- a/tests/baselines/reference/instanceMemberAssignsToClassPrototype.errors.txt
+++ b/tests/baselines/reference/instanceMemberAssignsToClassPrototype.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclarations/instanceMemberAssignsToClassPrototype.ts(7,9): error TS2322: Type '() => void' is not assignable to type '(x: number) => number'.
-  Type 'void' is not assignable to type 'number'.
+  Signature '(x: number): number' has no corresponding signature in '() => void'
+    Type 'void' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclarations/instanceMemberAssignsToClassPrototype.ts (1 errors) ====
@@ -12,7 +13,8 @@ tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclara
             C.prototype.bar = () => { } // error
             ~~~~~~~~~~~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type '(x: number) => number'.
-!!! error TS2322:   Type 'void' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): number' has no corresponding signature in '() => void'
+!!! error TS2322:     Type 'void' is not assignable to type 'number'.
             C.prototype.bar = (x) => x; // ok
             C.prototype.bar = (x: number) => 1; // ok
             return 1;
diff --git a/tests/baselines/reference/intTypeCheck.errors.txt b/tests/baselines/reference/intTypeCheck.errors.txt
index e48d1b1dc73..d9f3f021887 100644
--- a/tests/baselines/reference/intTypeCheck.errors.txt
+++ b/tests/baselines/reference/intTypeCheck.errors.txt
@@ -14,18 +14,27 @@ tests/cases/compiler/intTypeCheck.ts(106,20): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(106,21): error TS2304: Cannot find name 'i1'.
 tests/cases/compiler/intTypeCheck.ts(107,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
 tests/cases/compiler/intTypeCheck.ts(112,5): error TS2322: Type '{}' is not assignable to type 'i2'.
+  Signature '(): any' has no corresponding signature in '{}'
 tests/cases/compiler/intTypeCheck.ts(113,5): error TS2322: Type 'Object' is not assignable to type 'i2'.
+  Signature '(): any' has no corresponding signature in 'Object'
 tests/cases/compiler/intTypeCheck.ts(114,17): error TS2350: Only a void function can be called with the 'new' keyword.
 tests/cases/compiler/intTypeCheck.ts(115,5): error TS2322: Type 'Base' is not assignable to type 'i2'.
+  Signature '(): any' has no corresponding signature in 'Base'
 tests/cases/compiler/intTypeCheck.ts(120,5): error TS2322: Type 'boolean' is not assignable to type 'i2'.
+  Signature '(): any' has no corresponding signature in 'Boolean'
 tests/cases/compiler/intTypeCheck.ts(120,21): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(120,22): error TS2304: Cannot find name 'i2'.
 tests/cases/compiler/intTypeCheck.ts(121,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
 tests/cases/compiler/intTypeCheck.ts(126,5): error TS2322: Type '{}' is not assignable to type 'i3'.
+  Signature 'new (): any' has no corresponding signature in '{}'
 tests/cases/compiler/intTypeCheck.ts(127,5): error TS2322: Type 'Object' is not assignable to type 'i3'.
+  Signature 'new (): any' has no corresponding signature in 'Object'
 tests/cases/compiler/intTypeCheck.ts(129,5): error TS2322: Type 'Base' is not assignable to type 'i3'.
+  Signature 'new (): any' has no corresponding signature in 'Base'
 tests/cases/compiler/intTypeCheck.ts(131,5): error TS2322: Type '() => void' is not assignable to type 'i3'.
+  Signature 'new (): any' has no corresponding signature in '() => void'
 tests/cases/compiler/intTypeCheck.ts(134,5): error TS2322: Type 'boolean' is not assignable to type 'i3'.
+  Signature 'new (): any' has no corresponding signature in 'Boolean'
 tests/cases/compiler/intTypeCheck.ts(134,21): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(134,22): error TS2304: Cannot find name 'i3'.
 tests/cases/compiler/intTypeCheck.ts(135,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
@@ -50,20 +59,30 @@ tests/cases/compiler/intTypeCheck.ts(162,21): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(162,22): error TS2304: Cannot find name 'i5'.
 tests/cases/compiler/intTypeCheck.ts(163,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
 tests/cases/compiler/intTypeCheck.ts(168,5): error TS2322: Type '{}' is not assignable to type 'i6'.
+  Signature '(): any' has no corresponding signature in '{}'
 tests/cases/compiler/intTypeCheck.ts(169,5): error TS2322: Type 'Object' is not assignable to type 'i6'.
+  Signature '(): any' has no corresponding signature in 'Object'
 tests/cases/compiler/intTypeCheck.ts(170,17): error TS2350: Only a void function can be called with the 'new' keyword.
 tests/cases/compiler/intTypeCheck.ts(171,5): error TS2322: Type 'Base' is not assignable to type 'i6'.
+  Signature '(): any' has no corresponding signature in 'Base'
 tests/cases/compiler/intTypeCheck.ts(173,5): error TS2322: Type '() => void' is not assignable to type 'i6'.
-  Type 'void' is not assignable to type 'number'.
+  Signature '(): number' has no corresponding signature in '() => void'
+    Type 'void' is not assignable to type 'number'.
 tests/cases/compiler/intTypeCheck.ts(176,5): error TS2322: Type 'boolean' is not assignable to type 'i6'.
+  Signature '(): any' has no corresponding signature in 'Boolean'
 tests/cases/compiler/intTypeCheck.ts(176,21): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(176,22): error TS2304: Cannot find name 'i6'.
 tests/cases/compiler/intTypeCheck.ts(177,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
 tests/cases/compiler/intTypeCheck.ts(182,5): error TS2322: Type '{}' is not assignable to type 'i7'.
+  Signature 'new (): any' has no corresponding signature in '{}'
 tests/cases/compiler/intTypeCheck.ts(183,5): error TS2322: Type 'Object' is not assignable to type 'i7'.
+  Signature 'new (): any' has no corresponding signature in 'Object'
 tests/cases/compiler/intTypeCheck.ts(185,17): error TS2352: Neither type 'Base' nor type 'i7' is assignable to the other.
+  Signature 'new (): any' has no corresponding signature in 'Base'
 tests/cases/compiler/intTypeCheck.ts(187,5): error TS2322: Type '() => void' is not assignable to type 'i7'.
+  Signature 'new (): any' has no corresponding signature in '() => void'
 tests/cases/compiler/intTypeCheck.ts(190,5): error TS2322: Type 'boolean' is not assignable to type 'i7'.
+  Signature 'new (): any' has no corresponding signature in 'Boolean'
 tests/cases/compiler/intTypeCheck.ts(190,21): error TS1109: Expression expected.
 tests/cases/compiler/intTypeCheck.ts(190,22): error TS2304: Cannot find name 'i7'.
 tests/cases/compiler/intTypeCheck.ts(191,17): error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.
@@ -216,15 +235,18 @@ tests/cases/compiler/intTypeCheck.ts(205,17): error TS2351: Cannot use 'new' wit
     var obj12: i2 = {};
         ~~~~~
 !!! error TS2322: Type '{}' is not assignable to type 'i2'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in '{}'
     var obj13: i2 = new Object();
         ~~~~~
 !!! error TS2322: Type 'Object' is not assignable to type 'i2'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Object'
     var obj14: i2 = new obj11;
                     ~~~~~~~~~
 !!! error TS2350: Only a void function can be called with the 'new' keyword.
     var obj15: i2 = new Base;
         ~~~~~
 !!! error TS2322: Type 'Base' is not assignable to type 'i2'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Base'
     var obj16: i2 = null;
     var obj17: i2 = function ():any { return 0; };
     //var obj18: i2 = function foo() { };
@@ -232,6 +254,7 @@ tests/cases/compiler/intTypeCheck.ts(205,17): error TS2351: Cannot use 'new' wit
     var obj20: i2 = new <i2> anyVar;
         ~~~~~
 !!! error TS2322: Type 'boolean' is not assignable to type 'i2'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Boolean'
                         ~
 !!! error TS1109: Expression expected.
                          ~~
@@ -246,22 +269,27 @@ tests/cases/compiler/intTypeCheck.ts(205,17): error TS2351: Cannot use 'new' wit
     var obj23: i3 = {};
         ~~~~~
 !!! error TS2322: Type '{}' is not assignable to type 'i3'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '{}'
     var obj24: i3 = new Object();
         ~~~~~
 !!! error TS2322: Type 'Object' is not assignable to type 'i3'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Object'
     var obj25: i3 = new obj22;
     var obj26: i3 = new Base;
         ~~~~~
 !!! error TS2322: Type 'Base' is not assignable to type 'i3'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Base'
     var obj27: i3 = null;
     var obj28: i3 = function () { };
         ~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type 'i3'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '() => void'
     //var obj29: i3 = function foo() { };
     var obj30: i3 = <i3> anyVar;
     var obj31: i3 = new <i3> anyVar;
         ~~~~~
 !!! error TS2322: Type 'boolean' is not assignable to type 'i3'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Boolean'
                         ~
 !!! error TS1109: Expression expected.
                          ~~
@@ -338,25 +366,30 @@ tests/cases/compiler/intTypeCheck.ts(205,17): error TS2351: Cannot use 'new' wit
     var obj56: i6 = {};
         ~~~~~
 !!! error TS2322: Type '{}' is not assignable to type 'i6'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in '{}'
     var obj57: i6 = new Object();
         ~~~~~
 !!! error TS2322: Type 'Object' is not assignable to type 'i6'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Object'
     var obj58: i6 = new obj55;
                     ~~~~~~~~~
 !!! error TS2350: Only a void function can be called with the 'new' keyword.
     var obj59: i6 = new Base;
         ~~~~~
 !!! error TS2322: Type 'Base' is not assignable to type 'i6'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Base'
     var obj60: i6 = null;
     var obj61: i6 = function () { };
         ~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type 'i6'.
-!!! error TS2322:   Type 'void' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '() => void'
+!!! error TS2322:     Type 'void' is not assignable to type 'number'.
     //var obj62: i6 = function foo() { };
     var obj63: i6 = <i6> anyVar;
     var obj64: i6 = new <i6> anyVar;
         ~~~~~
 !!! error TS2322: Type 'boolean' is not assignable to type 'i6'.
+!!! error TS2322:   Signature '(): any' has no corresponding signature in 'Boolean'
                         ~
 !!! error TS1109: Expression expected.
                          ~~
@@ -371,22 +404,27 @@ tests/cases/compiler/intTypeCheck.ts(205,17): error TS2351: Cannot use 'new' wit
     var obj67: i7 = {};
         ~~~~~
 !!! error TS2322: Type '{}' is not assignable to type 'i7'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '{}'
     var obj68: i7 = new Object();
         ~~~~~
 !!! error TS2322: Type 'Object' is not assignable to type 'i7'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Object'
     var obj69: i7 = new obj66;
     var obj70: i7 = <i7>new Base;
                     ~~~~~~~~~~~~
 !!! error TS2352: Neither type 'Base' nor type 'i7' is assignable to the other.
+!!! error TS2352:   Signature 'new (): any' has no corresponding signature in 'Base'
     var obj71: i7 = null;
     var obj72: i7 = function () { };
         ~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type 'i7'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '() => void'
     //var obj73: i7 = function foo() { };
     var obj74: i7 = <i7> anyVar;
     var obj75: i7 = new <i7> anyVar;
         ~~~~~
 !!! error TS2322: Type 'boolean' is not assignable to type 'i7'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Boolean'
                         ~
 !!! error TS1109: Expression expected.
                          ~~
diff --git a/tests/baselines/reference/interfaceAssignmentCompat.errors.txt b/tests/baselines/reference/interfaceAssignmentCompat.errors.txt
index 237358b42de..a1198d9fd37 100644
--- a/tests/baselines/reference/interfaceAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/interfaceAssignmentCompat.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/compiler/interfaceAssignmentCompat.ts(32,18): error TS2345: Argument of type '(a: IFrenchEye, b: IFrenchEye) => number' is not assignable to parameter of type '(a: IEye, b: IEye) => number'.
-  Types of parameters 'a' and 'a' are incompatible.
-    Type 'IFrenchEye' is not assignable to type 'IEye'.
-      Property 'color' is missing in type 'IFrenchEye'.
+  Signature '(a: IEye, b: IEye): number' has no corresponding signature in '(a: IFrenchEye, b: IFrenchEye) => number'
+    Types of parameters 'a' and 'a' are incompatible.
+      Type 'IFrenchEye' is not assignable to type 'IEye'.
+        Property 'color' is missing in type 'IFrenchEye'.
 tests/cases/compiler/interfaceAssignmentCompat.ts(37,29): error TS2339: Property '_map' does not exist on type 'typeof Color'.
 tests/cases/compiler/interfaceAssignmentCompat.ts(42,13): error TS2322: Type 'IEye' is not assignable to type 'IFrenchEye'.
   Property 'coleur' is missing in type 'IEye'.
@@ -44,9 +45,10 @@ tests/cases/compiler/interfaceAssignmentCompat.ts(44,9): error TS2322: Type 'IEy
             x=x.sort(CompareYeux); // parameter mismatch
                      ~~~~~~~~~~~
 !!! error TS2345: Argument of type '(a: IFrenchEye, b: IFrenchEye) => number' is not assignable to parameter of type '(a: IEye, b: IEye) => number'.
-!!! error TS2345:   Types of parameters 'a' and 'a' are incompatible.
-!!! error TS2345:     Type 'IFrenchEye' is not assignable to type 'IEye'.
-!!! error TS2345:       Property 'color' is missing in type 'IFrenchEye'.
+!!! error TS2345:   Signature '(a: IEye, b: IEye): number' has no corresponding signature in '(a: IFrenchEye, b: IFrenchEye) => number'
+!!! error TS2345:     Types of parameters 'a' and 'a' are incompatible.
+!!! error TS2345:       Type 'IFrenchEye' is not assignable to type 'IEye'.
+!!! error TS2345:         Property 'color' is missing in type 'IFrenchEye'.
             // type of z inferred from specialized array type
             var z=x.sort(CompareEyes); // ok
     
diff --git a/tests/baselines/reference/interfaceImplementation1.errors.txt b/tests/baselines/reference/interfaceImplementation1.errors.txt
index 45b011c6929..826e5650c83 100644
--- a/tests/baselines/reference/interfaceImplementation1.errors.txt
+++ b/tests/baselines/reference/interfaceImplementation1.errors.txt
@@ -3,6 +3,7 @@ tests/cases/compiler/interfaceImplementation1.ts(12,7): error TS2420: Class 'C1'
 tests/cases/compiler/interfaceImplementation1.ts(12,7): error TS2420: Class 'C1' incorrectly implements interface 'I2'.
   Property 'iFn' is private in type 'C1' but not in type 'I2'.
 tests/cases/compiler/interfaceImplementation1.ts(34,5): error TS2322: Type '() => C2' is not assignable to type 'I4'.
+  Signature 'new (): I3' has no corresponding signature in '() => C2'
 
 
 ==== tests/cases/compiler/interfaceImplementation1.ts (3 errors) ====
@@ -48,6 +49,7 @@ tests/cases/compiler/interfaceImplementation1.ts(34,5): error TS2322: Type '() =
     var a:I4 = function(){ 
         ~
 !!! error TS2322: Type '() => C2' is not assignable to type 'I4'.
+!!! error TS2322:   Signature 'new (): I3' has no corresponding signature in '() => C2'
         return new C2();
     }
     new a();
diff --git a/tests/baselines/reference/interfaceImplementation7.errors.txt b/tests/baselines/reference/interfaceImplementation7.errors.txt
index b297015dfbe..531398ba532 100644
--- a/tests/baselines/reference/interfaceImplementation7.errors.txt
+++ b/tests/baselines/reference/interfaceImplementation7.errors.txt
@@ -3,8 +3,9 @@ tests/cases/compiler/interfaceImplementation7.ts(4,11): error TS2320: Interface
 tests/cases/compiler/interfaceImplementation7.ts(7,7): error TS2420: Class 'C1' incorrectly implements interface 'i4'.
   Types of property 'name' are incompatible.
     Type '() => string' is not assignable to type '() => { s: string; n: number; }'.
-      Type 'string' is not assignable to type '{ s: string; n: number; }'.
-        Property 's' is missing in type 'String'.
+      Signature '(): { s: string; n: number; }' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type '{ s: string; n: number; }'.
+          Property 's' is missing in type 'String'.
 
 
 ==== tests/cases/compiler/interfaceImplementation7.ts (2 errors) ====
@@ -22,8 +23,9 @@ tests/cases/compiler/interfaceImplementation7.ts(7,7): error TS2420: Class 'C1'
 !!! error TS2420: Class 'C1' incorrectly implements interface 'i4'.
 !!! error TS2420:   Types of property 'name' are incompatible.
 !!! error TS2420:     Type '() => string' is not assignable to type '() => { s: string; n: number; }'.
-!!! error TS2420:       Type 'string' is not assignable to type '{ s: string; n: number; }'.
-!!! error TS2420:         Property 's' is missing in type 'String'.
+!!! error TS2420:       Signature '(): { s: string; n: number; }' has no corresponding signature in '() => string'
+!!! error TS2420:         Type 'string' is not assignable to type '{ s: string; n: number; }'.
+!!! error TS2420:           Property 's' is missing in type 'String'.
         public name(): string { return ""; }
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/invalidBooleanAssignments.errors.txt b/tests/baselines/reference/invalidBooleanAssignments.errors.txt
index 84ced226113..ddedc16f28d 100644
--- a/tests/baselines/reference/invalidBooleanAssignments.errors.txt
+++ b/tests/baselines/reference/invalidBooleanAssignments.errors.txt
@@ -7,6 +7,7 @@ tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(12
 tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(15,5): error TS2322: Type 'boolean' is not assignable to type 'I'.
   Property 'bar' is missing in type 'Boolean'.
 tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(17,5): error TS2322: Type 'boolean' is not assignable to type '() => string'.
+  Signature '(): string' has no corresponding signature in 'Boolean'
 tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(21,1): error TS2364: Invalid left-hand side of assignment expression.
 tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(24,5): error TS2322: Type 'boolean' is not assignable to type 'T'.
 tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(26,1): error TS2364: Invalid left-hand side of assignment expression.
@@ -46,6 +47,7 @@ tests/cases/conformance/types/primitives/boolean/invalidBooleanAssignments.ts(26
     var h: { (): string } = x;
         ~
 !!! error TS2322: Type 'boolean' is not assignable to type '() => string'.
+!!! error TS2322:   Signature '(): string' has no corresponding signature in 'Boolean'
     var h2: { toString(): string } = x; // no error
     
     module M { export var a = 1; }
diff --git a/tests/baselines/reference/iteratorSpreadInArray9.errors.txt b/tests/baselines/reference/iteratorSpreadInArray9.errors.txt
index 90b8bdbeb46..cc32db8a373 100644
--- a/tests/baselines/reference/iteratorSpreadInArray9.errors.txt
+++ b/tests/baselines/reference/iteratorSpreadInArray9.errors.txt
@@ -1,11 +1,13 @@
 tests/cases/conformance/es6/spread/iteratorSpreadInArray9.ts(1,17): error TS2322: Type 'SymbolIterator' is not assignable to type 'Iterable<symbol>'.
   Types of property '[Symbol.iterator]' are incompatible.
     Type '() => SymbolIterator' is not assignable to type '() => Iterator<symbol>'.
-      Type 'SymbolIterator' is not assignable to type 'Iterator<symbol>'.
-        Types of property 'next' are incompatible.
-          Type '() => { value: symbol; }' is not assignable to type '(value?: any) => IteratorResult<symbol>'.
-            Type '{ value: symbol; }' is not assignable to type 'IteratorResult<symbol>'.
-              Property 'done' is missing in type '{ value: symbol; }'.
+      Signature '(): Iterator<symbol>' has no corresponding signature in '() => SymbolIterator'
+        Type 'SymbolIterator' is not assignable to type 'Iterator<symbol>'.
+          Types of property 'next' are incompatible.
+            Type '() => { value: symbol; }' is not assignable to type '(value?: any) => IteratorResult<symbol>'.
+              Signature '(value?: any): IteratorResult<symbol>' has no corresponding signature in '() => { value: symbol; }'
+                Type '{ value: symbol; }' is not assignable to type 'IteratorResult<symbol>'.
+                  Property 'done' is missing in type '{ value: symbol; }'.
 
 
 ==== tests/cases/conformance/es6/spread/iteratorSpreadInArray9.ts (1 errors) ====
@@ -14,11 +16,13 @@ tests/cases/conformance/es6/spread/iteratorSpreadInArray9.ts(1,17): error TS2322
 !!! error TS2322: Type 'SymbolIterator' is not assignable to type 'Iterable<symbol>'.
 !!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
 !!! error TS2322:     Type '() => SymbolIterator' is not assignable to type '() => Iterator<symbol>'.
-!!! error TS2322:       Type 'SymbolIterator' is not assignable to type 'Iterator<symbol>'.
-!!! error TS2322:         Types of property 'next' are incompatible.
-!!! error TS2322:           Type '() => { value: symbol; }' is not assignable to type '(value?: any) => IteratorResult<symbol>'.
-!!! error TS2322:             Type '{ value: symbol; }' is not assignable to type 'IteratorResult<symbol>'.
-!!! error TS2322:               Property 'done' is missing in type '{ value: symbol; }'.
+!!! error TS2322:       Signature '(): Iterator<symbol>' has no corresponding signature in '() => SymbolIterator'
+!!! error TS2322:         Type 'SymbolIterator' is not assignable to type 'Iterator<symbol>'.
+!!! error TS2322:           Types of property 'next' are incompatible.
+!!! error TS2322:             Type '() => { value: symbol; }' is not assignable to type '(value?: any) => IteratorResult<symbol>'.
+!!! error TS2322:               Signature '(value?: any): IteratorResult<symbol>' has no corresponding signature in '() => { value: symbol; }'
+!!! error TS2322:                 Type '{ value: symbol; }' is not assignable to type 'IteratorResult<symbol>'.
+!!! error TS2322:                   Property 'done' is missing in type '{ value: symbol; }'.
     
     class SymbolIterator {
         next() {
diff --git a/tests/baselines/reference/lambdaArgCrash.errors.txt b/tests/baselines/reference/lambdaArgCrash.errors.txt
index bf1c4dd01bd..658534334f5 100644
--- a/tests/baselines/reference/lambdaArgCrash.errors.txt
+++ b/tests/baselines/reference/lambdaArgCrash.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/lambdaArgCrash.ts(27,25): error TS2304: Cannot find name 'ItemSet'.
 tests/cases/compiler/lambdaArgCrash.ts(29,14): error TS2345: Argument of type '(items: any) => void' is not assignable to parameter of type '() => any'.
+  Signature '(): any' has no corresponding signature in '(items: any) => void'
 
 
 ==== tests/cases/compiler/lambdaArgCrash.ts (2 errors) ====
@@ -36,6 +37,7 @@ tests/cases/compiler/lambdaArgCrash.ts(29,14): error TS2345: Argument of type '(
     	 	super.add(listener);
     	 	          ~~~~~~~~
 !!! error TS2345: Argument of type '(items: any) => void' is not assignable to parameter of type '() => any'.
+!!! error TS2345:   Signature '(): any' has no corresponding signature in '(items: any) => void'
     
     	}
     
diff --git a/tests/baselines/reference/multipleInheritance.errors.txt b/tests/baselines/reference/multipleInheritance.errors.txt
index 19ef1e755e3..def2fcbd813 100644
--- a/tests/baselines/reference/multipleInheritance.errors.txt
+++ b/tests/baselines/reference/multipleInheritance.errors.txt
@@ -3,6 +3,7 @@ tests/cases/compiler/multipleInheritance.ts(18,21): error TS1174: Classes can on
 tests/cases/compiler/multipleInheritance.ts(34,7): error TS2415: Class 'Baad' incorrectly extends base class 'Good'.
   Types of property 'g' are incompatible.
     Type '(n: number) => number' is not assignable to type '() => number'.
+      Signature '(): number' has no corresponding signature in '(n: number) => number'
 tests/cases/compiler/multipleInheritance.ts(35,12): error TS2425: Class 'Good' defines instance member property 'f', but extended class 'Baad' defines it as instance member function.
 
 
@@ -49,6 +50,7 @@ tests/cases/compiler/multipleInheritance.ts(35,12): error TS2425: Class 'Good' d
 !!! error TS2415: Class 'Baad' incorrectly extends base class 'Good'.
 !!! error TS2415:   Types of property 'g' are incompatible.
 !!! error TS2415:     Type '(n: number) => number' is not assignable to type '() => number'.
+!!! error TS2415:       Signature '(): number' has no corresponding signature in '(n: number) => number'
         public f(): number { return 0; }
                ~
 !!! error TS2425: Class 'Good' defines instance member property 'f', but extended class 'Baad' defines it as instance member function.
diff --git a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
index c4ee3ea17b2..6bc3ec86f72 100644
--- a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
@@ -1,15 +1,18 @@
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(7,1): error TS2322: Type 'I' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => void'
+        Type 'void' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(14,1): error TS2322: Type 'C' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => void'
+        Type 'void' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(20,1): error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => void'
+        Type 'void' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts (3 errors) ====
@@ -24,7 +27,8 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type 'I' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => void'
+!!! error TS2322:         Type 'void' is not assignable to type 'string'.
     i = o; // ok
     
     class C {
@@ -36,7 +40,8 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type 'C' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => void'
+!!! error TS2322:         Type 'void' is not assignable to type 'string'.
     c = o; // ok
     
     var a = {
@@ -47,5 +52,6 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => void'
+!!! error TS2322:         Type 'void' is not assignable to type 'string'.
     a = o; // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
index a88796b390e..174707a8d22 100644
--- a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
+++ b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
@@ -1,23 +1,28 @@
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(7,1): error TS2322: Type 'I' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => number'
+        Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(8,1): error TS2322: Type 'Object' is not assignable to type 'I'.
   Types of property 'toString' are incompatible.
     Type '() => string' is not assignable to type '() => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(14,1): error TS2322: Type 'C' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => number'
+        Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(15,1): error TS2322: Type 'Object' is not assignable to type 'C'.
   Types of property 'toString' are incompatible.
     Type '() => string' is not assignable to type '() => number'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(20,1): error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
   Types of property 'toString' are incompatible.
     Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+      Signature '(): string' has no corresponding signature in '() => void'
+        Type 'void' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts (5 errors) ====
@@ -32,13 +37,15 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type 'I' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => number'
+!!! error TS2322:         Type 'number' is not assignable to type 'string'.
     i = o; // error
     ~
 !!! error TS2322: Type 'Object' is not assignable to type 'I'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => string' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2322:         Type 'string' is not assignable to type 'number'.
     
     class C {
         toString(): number { return 1; }
@@ -49,13 +56,15 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type 'C' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => number'
+!!! error TS2322:         Type 'number' is not assignable to type 'string'.
     c = o; // error
     ~
 !!! error TS2322: Type 'Object' is not assignable to type 'C'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => string' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => string'
+!!! error TS2322:         Type 'string' is not assignable to type 'number'.
     
     var a = {
         toString: () => { }
@@ -65,5 +74,6 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
 !!! error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
 !!! error TS2322:   Types of property 'toString' are incompatible.
 !!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:       Signature '(): string' has no corresponding signature in '() => void'
+!!! error TS2322:         Type 'void' is not assignable to type 'string'.
     a = o; // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt b/tests/baselines/reference/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
index 30b40f431a7..6767d053498 100644
--- a/tests/baselines/reference/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
@@ -1,5 +1,7 @@
 tests/cases/conformance/types/members/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.ts(8,1): error TS2322: Type 'Object' is not assignable to type 'I'.
+  Signature '(): void' has no corresponding signature in 'Object'
 tests/cases/conformance/types/members/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.ts(14,1): error TS2322: Type 'Object' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in 'Object'
 
 
 ==== tests/cases/conformance/types/members/objectTypeWithCallSignatureHidingMembersOfFunctionAssignmentCompat.ts (2 errors) ====
@@ -13,6 +15,7 @@ tests/cases/conformance/types/members/objectTypeWithCallSignatureHidingMembersOf
     i = f;
     ~
 !!! error TS2322: Type 'Object' is not assignable to type 'I'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Object'
     
     var a: {
         (): void
@@ -20,4 +23,5 @@ tests/cases/conformance/types/members/objectTypeWithCallSignatureHidingMembersOf
     f = a;
     a = f;
     ~
-!!! error TS2322: Type 'Object' is not assignable to type '() => void'.
\ No newline at end of file
+!!! error TS2322: Type 'Object' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Object'
\ No newline at end of file
diff --git a/tests/baselines/reference/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt b/tests/baselines/reference/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
index 0faba936715..92fdf725efe 100644
--- a/tests/baselines/reference/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.errors.txt
@@ -1,5 +1,7 @@
 tests/cases/conformance/types/members/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.ts(8,1): error TS2322: Type 'Object' is not assignable to type 'I'.
+  Signature 'new (): any' has no corresponding signature in 'Object'
 tests/cases/conformance/types/members/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.ts(14,1): error TS2322: Type 'Object' is not assignable to type 'new () => any'.
+  Signature 'new (): any' has no corresponding signature in 'Object'
 
 
 ==== tests/cases/conformance/types/members/objectTypeWithConstructSignatureHidingMembersOfFunctionAssignmentCompat.ts (2 errors) ====
@@ -13,6 +15,7 @@ tests/cases/conformance/types/members/objectTypeWithConstructSignatureHidingMemb
     i = f;
     ~
 !!! error TS2322: Type 'Object' is not assignable to type 'I'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Object'
     
     var a: {
         new(): any
@@ -20,4 +23,5 @@ tests/cases/conformance/types/members/objectTypeWithConstructSignatureHidingMemb
     f = a;
     a = f;
     ~
-!!! error TS2322: Type 'Object' is not assignable to type 'new () => any'.
\ No newline at end of file
+!!! error TS2322: Type 'Object' is not assignable to type 'new () => any'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in 'Object'
\ No newline at end of file
diff --git a/tests/baselines/reference/optionalFunctionArgAssignability.errors.txt b/tests/baselines/reference/optionalFunctionArgAssignability.errors.txt
index 52fb45e40d2..43d7b633052 100644
--- a/tests/baselines/reference/optionalFunctionArgAssignability.errors.txt
+++ b/tests/baselines/reference/optionalFunctionArgAssignability.errors.txt
@@ -1,8 +1,10 @@
 tests/cases/compiler/optionalFunctionArgAssignability.ts(7,1): error TS2322: Type '<U>(onFulFill?: (value: number) => U, onReject?: (reason: any) => U) => Promise<U>' is not assignable to type '<U>(onFulfill?: (value: string) => U, onReject?: (reason: any) => U) => Promise<U>'.
-  Types of parameters 'onFulFill' and 'onFulfill' are incompatible.
-    Type '(value: number) => any' is not assignable to type '(value: string) => any'.
-      Types of parameters 'value' and 'value' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+  Signature '<U>(onFulfill?: (value: string) => U, onReject?: (reason: any) => U): Promise<U>' has no corresponding signature in '<U>(onFulFill?: (value: number) => U, onReject?: (reason: any) => U) => Promise<U>'
+    Types of parameters 'onFulFill' and 'onFulfill' are incompatible.
+      Type '(value: number) => any' is not assignable to type '(value: string) => any'.
+        Signature '(value: string): any' has no corresponding signature in '(value: number) => any'
+          Types of parameters 'value' and 'value' are incompatible.
+            Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/optionalFunctionArgAssignability.ts (1 errors) ====
@@ -15,8 +17,10 @@ tests/cases/compiler/optionalFunctionArgAssignability.ts(7,1): error TS2322: Typ
     a = b; // error because number is not assignable to string
     ~
 !!! error TS2322: Type '<U>(onFulFill?: (value: number) => U, onReject?: (reason: any) => U) => Promise<U>' is not assignable to type '<U>(onFulfill?: (value: string) => U, onReject?: (reason: any) => U) => Promise<U>'.
-!!! error TS2322:   Types of parameters 'onFulFill' and 'onFulfill' are incompatible.
-!!! error TS2322:     Type '(value: number) => any' is not assignable to type '(value: string) => any'.
-!!! error TS2322:       Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2322:         Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   Signature '<U>(onFulfill?: (value: string) => U, onReject?: (reason: any) => U): Promise<U>' has no corresponding signature in '<U>(onFulFill?: (value: number) => U, onReject?: (reason: any) => U) => Promise<U>'
+!!! error TS2322:     Types of parameters 'onFulFill' and 'onFulfill' are incompatible.
+!!! error TS2322:       Type '(value: number) => any' is not assignable to type '(value: string) => any'.
+!!! error TS2322:         Signature '(value: string): any' has no corresponding signature in '(value: number) => any'
+!!! error TS2322:           Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2322:             Type 'number' is not assignable to type 'string'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/optionalParamAssignmentCompat.errors.txt b/tests/baselines/reference/optionalParamAssignmentCompat.errors.txt
index de02509d124..4d8f23385fd 100644
--- a/tests/baselines/reference/optionalParamAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/optionalParamAssignmentCompat.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/optionalParamAssignmentCompat.ts(10,5): error TS2322: Type '(p1?: string) => I1' is not assignable to type 'I1'.
-  Types of parameters 'p1' and 'p1' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(p1: number, p2: string): void' has no corresponding signature in '(p1?: string) => I1'
+    Types of parameters 'p1' and 'p1' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/optionalParamAssignmentCompat.ts (1 errors) ====
@@ -16,6 +17,7 @@ tests/cases/compiler/optionalParamAssignmentCompat.ts(10,5): error TS2322: Type
     var d: I1 = i2.m1; // should error
         ~
 !!! error TS2322: Type '(p1?: string) => I1' is not assignable to type 'I1'.
-!!! error TS2322:   Types of parameters 'p1' and 'p1' are incompatible.
-!!! error TS2322:     Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(p1: number, p2: string): void' has no corresponding signature in '(p1?: string) => I1'
+!!! error TS2322:     Types of parameters 'p1' and 'p1' are incompatible.
+!!! error TS2322:       Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/optionalParamTypeComparison.errors.txt b/tests/baselines/reference/optionalParamTypeComparison.errors.txt
index 98a07570c65..8e3237a80b1 100644
--- a/tests/baselines/reference/optionalParamTypeComparison.errors.txt
+++ b/tests/baselines/reference/optionalParamTypeComparison.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/optionalParamTypeComparison.ts(4,1): error TS2322: Type '(s: string, b?: boolean) => void' is not assignable to type '(s: string, n?: number) => void'.
-  Types of parameters 'b' and 'n' are incompatible.
-    Type 'boolean' is not assignable to type 'number'.
+  Signature '(s: string, n?: number): void' has no corresponding signature in '(s: string, b?: boolean) => void'
+    Types of parameters 'b' and 'n' are incompatible.
+      Type 'boolean' is not assignable to type 'number'.
 tests/cases/compiler/optionalParamTypeComparison.ts(5,1): error TS2322: Type '(s: string, n?: number) => void' is not assignable to type '(s: string, b?: boolean) => void'.
-  Types of parameters 'n' and 'b' are incompatible.
-    Type 'number' is not assignable to type 'boolean'.
+  Signature '(s: string, b?: boolean): void' has no corresponding signature in '(s: string, n?: number) => void'
+    Types of parameters 'n' and 'b' are incompatible.
+      Type 'number' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/optionalParamTypeComparison.ts (2 errors) ====
@@ -13,10 +15,12 @@ tests/cases/compiler/optionalParamTypeComparison.ts(5,1): error TS2322: Type '(s
     f = g;
     ~
 !!! error TS2322: Type '(s: string, b?: boolean) => void' is not assignable to type '(s: string, n?: number) => void'.
-!!! error TS2322:   Types of parameters 'b' and 'n' are incompatible.
-!!! error TS2322:     Type 'boolean' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(s: string, n?: number): void' has no corresponding signature in '(s: string, b?: boolean) => void'
+!!! error TS2322:     Types of parameters 'b' and 'n' are incompatible.
+!!! error TS2322:       Type 'boolean' is not assignable to type 'number'.
     g = f;
     ~
 !!! error TS2322: Type '(s: string, n?: number) => void' is not assignable to type '(s: string, b?: boolean) => void'.
-!!! error TS2322:   Types of parameters 'n' and 'b' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'boolean'.
\ No newline at end of file
+!!! error TS2322:   Signature '(s: string, b?: boolean): void' has no corresponding signature in '(s: string, n?: number) => void'
+!!! error TS2322:     Types of parameters 'n' and 'b' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'boolean'.
\ No newline at end of file
diff --git a/tests/baselines/reference/overloadOnConstInheritance2.errors.txt b/tests/baselines/reference/overloadOnConstInheritance2.errors.txt
index 4870106f474..3b8d8c80e58 100644
--- a/tests/baselines/reference/overloadOnConstInheritance2.errors.txt
+++ b/tests/baselines/reference/overloadOnConstInheritance2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/overloadOnConstInheritance2.ts(5,11): error TS2430: Interface 'Deriver' incorrectly extends interface 'Base'.
   Types of property 'addEventListener' are incompatible.
     Type '(x: "bar") => string' is not assignable to type '{ (x: string): any; (x: "foo"): string; }'.
+      Signature '(x: string): any' has no corresponding signature in '(x: "bar") => string'
 tests/cases/compiler/overloadOnConstInheritance2.ts(6,5): error TS2382: Specialized overload signature is not assignable to any non-specialized signature.
 
 
@@ -14,6 +15,7 @@ tests/cases/compiler/overloadOnConstInheritance2.ts(6,5): error TS2382: Speciali
 !!! error TS2430: Interface 'Deriver' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'addEventListener' are incompatible.
 !!! error TS2430:     Type '(x: "bar") => string' is not assignable to type '{ (x: string): any; (x: "foo"): string; }'.
+!!! error TS2430:       Signature '(x: string): any' has no corresponding signature in '(x: "bar") => string'
         addEventListener(x: 'bar'): string; // shouldn't need to redeclare the string overload
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2382: Specialized overload signature is not assignable to any non-specialized signature.
diff --git a/tests/baselines/reference/overloadOnConstInheritance3.errors.txt b/tests/baselines/reference/overloadOnConstInheritance3.errors.txt
index b338f9795d7..062db72ac51 100644
--- a/tests/baselines/reference/overloadOnConstInheritance3.errors.txt
+++ b/tests/baselines/reference/overloadOnConstInheritance3.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/overloadOnConstInheritance3.ts(4,11): error TS2430: Interface 'Deriver' incorrectly extends interface 'Base'.
   Types of property 'addEventListener' are incompatible.
     Type '{ (x: "bar"): string; (x: "foo"): string; }' is not assignable to type '(x: string) => any'.
+      Signature '(x: string): any' has no corresponding signature in '{ (x: "bar"): string; (x: "foo"): string; }'
 tests/cases/compiler/overloadOnConstInheritance3.ts(6,5): error TS2382: Specialized overload signature is not assignable to any non-specialized signature.
 tests/cases/compiler/overloadOnConstInheritance3.ts(7,5): error TS2382: Specialized overload signature is not assignable to any non-specialized signature.
 
@@ -14,6 +15,7 @@ tests/cases/compiler/overloadOnConstInheritance3.ts(7,5): error TS2382: Speciali
 !!! error TS2430: Interface 'Deriver' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'addEventListener' are incompatible.
 !!! error TS2430:     Type '{ (x: "bar"): string; (x: "foo"): string; }' is not assignable to type '(x: string) => any'.
+!!! error TS2430:       Signature '(x: string): any' has no corresponding signature in '{ (x: "bar"): string; (x: "foo"): string; }'
         // shouldn't need to redeclare the string overload
         addEventListener(x: 'bar'): string;
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/tests/baselines/reference/overloadResolutionOverCTLambda.errors.txt b/tests/baselines/reference/overloadResolutionOverCTLambda.errors.txt
index 9fc11b681c7..54e43e0b248 100644
--- a/tests/baselines/reference/overloadResolutionOverCTLambda.errors.txt
+++ b/tests/baselines/reference/overloadResolutionOverCTLambda.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/overloadResolutionOverCTLambda.ts(2,5): error TS2345: Argument of type '(a: number) => number' is not assignable to parameter of type '(item: number) => boolean'.
-  Type 'number' is not assignable to type 'boolean'.
+  Signature '(item: number): boolean' has no corresponding signature in '(a: number) => number'
+    Type 'number' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/overloadResolutionOverCTLambda.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/compiler/overloadResolutionOverCTLambda.ts(2,5): error TS2345: Argum
     foo(a => a); // can not convert (number)=>bool to (number)=>number
         ~~~~~~
 !!! error TS2345: Argument of type '(a: number) => number' is not assignable to parameter of type '(item: number) => boolean'.
-!!! error TS2345:   Type 'number' is not assignable to type 'boolean'.
\ No newline at end of file
+!!! error TS2345:   Signature '(item: number): boolean' has no corresponding signature in '(a: number) => number'
+!!! error TS2345:     Type 'number' is not assignable to type 'boolean'.
\ No newline at end of file
diff --git a/tests/baselines/reference/overloadresolutionWithConstraintCheckingDeferred.errors.txt b/tests/baselines/reference/overloadresolutionWithConstraintCheckingDeferred.errors.txt
index 45c9f99b691..9658555f35b 100644
--- a/tests/baselines/reference/overloadresolutionWithConstraintCheckingDeferred.errors.txt
+++ b/tests/baselines/reference/overloadresolutionWithConstraintCheckingDeferred.errors.txt
@@ -4,9 +4,10 @@ tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(14,37):
 tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(16,5): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(16,38): error TS2344: Type 'D' does not satisfy the constraint 'A'.
 tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(18,27): error TS2345: Argument of type '(x: D) => G<D>' is not assignable to parameter of type '(x: B) => any'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'D' is not assignable to type 'B'.
-      Property 'x' is missing in type 'D'.
+  Signature '(x: B): any' has no corresponding signature in '(x: D) => G<D>'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'D' is not assignable to type 'B'.
+        Property 'x' is missing in type 'D'.
 tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(19,14): error TS2344: Type 'D' does not satisfy the constraint 'A'.
 
 
@@ -48,7 +49,8 @@ tests/cases/compiler/overloadresolutionWithConstraintCheckingDeferred.ts(19,14):
     });
     ~
 !!! error TS2345: Argument of type '(x: D) => G<D>' is not assignable to parameter of type '(x: B) => any'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'D' is not assignable to type 'B'.
-!!! error TS2345:       Property 'x' is missing in type 'D'.
+!!! error TS2345:   Signature '(x: B): any' has no corresponding signature in '(x: D) => G<D>'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'D' is not assignable to type 'B'.
+!!! error TS2345:         Property 'x' is missing in type 'D'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/overloadsWithProvisionalErrors.errors.txt b/tests/baselines/reference/overloadsWithProvisionalErrors.errors.txt
index daf057c9ebd..edc11299c9e 100644
--- a/tests/baselines/reference/overloadsWithProvisionalErrors.errors.txt
+++ b/tests/baselines/reference/overloadsWithProvisionalErrors.errors.txt
@@ -1,10 +1,12 @@
 tests/cases/compiler/overloadsWithProvisionalErrors.ts(6,6): error TS2345: Argument of type '(s: string) => {}' is not assignable to parameter of type '(s: string) => { a: number; b: number; }'.
-  Type '{}' is not assignable to type '{ a: number; b: number; }'.
-    Property 'a' is missing in type '{}'.
+  Signature '(s: string): { a: number; b: number; }' has no corresponding signature in '(s: string) => {}'
+    Type '{}' is not assignable to type '{ a: number; b: number; }'.
+      Property 'a' is missing in type '{}'.
 tests/cases/compiler/overloadsWithProvisionalErrors.ts(7,17): error TS2304: Cannot find name 'blah'.
 tests/cases/compiler/overloadsWithProvisionalErrors.ts(8,6): error TS2345: Argument of type '(s: string) => { a: any; }' is not assignable to parameter of type '(s: string) => { a: number; b: number; }'.
-  Type '{ a: any; }' is not assignable to type '{ a: number; b: number; }'.
-    Property 'b' is missing in type '{ a: any; }'.
+  Signature '(s: string): { a: number; b: number; }' has no corresponding signature in '(s: string) => { a: any; }'
+    Type '{ a: any; }' is not assignable to type '{ a: number; b: number; }'.
+      Property 'b' is missing in type '{ a: any; }'.
 tests/cases/compiler/overloadsWithProvisionalErrors.ts(8,17): error TS2304: Cannot find name 'blah'.
 
 
@@ -17,15 +19,17 @@ tests/cases/compiler/overloadsWithProvisionalErrors.ts(8,17): error TS2304: Cann
     func(s => ({})); // Error for no applicable overload (object type is missing a and b)
          ~~~~~~~~~
 !!! error TS2345: Argument of type '(s: string) => {}' is not assignable to parameter of type '(s: string) => { a: number; b: number; }'.
-!!! error TS2345:   Type '{}' is not assignable to type '{ a: number; b: number; }'.
-!!! error TS2345:     Property 'a' is missing in type '{}'.
+!!! error TS2345:   Signature '(s: string): { a: number; b: number; }' has no corresponding signature in '(s: string) => {}'
+!!! error TS2345:     Type '{}' is not assignable to type '{ a: number; b: number; }'.
+!!! error TS2345:       Property 'a' is missing in type '{}'.
     func(s => ({ a: blah, b: 3 })); // Only error inside the function, but not outside (since it would be applicable if not for the provisional error)
                     ~~~~
 !!! error TS2304: Cannot find name 'blah'.
     func(s => ({ a: blah })); // Two errors here, one for blah not being defined, and one for the overload since it would not be applicable anyway
          ~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(s: string) => { a: any; }' is not assignable to parameter of type '(s: string) => { a: number; b: number; }'.
-!!! error TS2345:   Type '{ a: any; }' is not assignable to type '{ a: number; b: number; }'.
-!!! error TS2345:     Property 'b' is missing in type '{ a: any; }'.
+!!! error TS2345:   Signature '(s: string): { a: number; b: number; }' has no corresponding signature in '(s: string) => { a: any; }'
+!!! error TS2345:     Type '{ a: any; }' is not assignable to type '{ a: number; b: number; }'.
+!!! error TS2345:       Property 'b' is missing in type '{ a: any; }'.
                     ~~~~
 !!! error TS2304: Cannot find name 'blah'.
\ No newline at end of file
diff --git a/tests/baselines/reference/parseTypes.errors.txt b/tests/baselines/reference/parseTypes.errors.txt
index baa5aaff738..c141b59e993 100644
--- a/tests/baselines/reference/parseTypes.errors.txt
+++ b/tests/baselines/reference/parseTypes.errors.txt
@@ -1,8 +1,11 @@
 tests/cases/compiler/parseTypes.ts(9,1): error TS2322: Type '(s: string) => void' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(s: string) => void'
 tests/cases/compiler/parseTypes.ts(10,1): error TS2322: Type '(s: string) => void' is not assignable to type '() => number'.
+  Signature '(): number' has no corresponding signature in '(s: string) => void'
 tests/cases/compiler/parseTypes.ts(11,1): error TS2322: Type '(s: string) => void' is not assignable to type '{ [x: number]: number; }'.
   Index signature is missing in type '(s: string) => void'.
 tests/cases/compiler/parseTypes.ts(12,1): error TS2322: Type '(s: string) => void' is not assignable to type 'new () => number'.
+  Signature 'new (): number' has no corresponding signature in '(s: string) => void'
 
 
 ==== tests/cases/compiler/parseTypes.ts (4 errors) ====
@@ -17,9 +20,11 @@ tests/cases/compiler/parseTypes.ts(12,1): error TS2322: Type '(s: string) => voi
     y=g;
     ~
 !!! error TS2322: Type '(s: string) => void' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(s: string) => void'
     x=g;
     ~
 !!! error TS2322: Type '(s: string) => void' is not assignable to type '() => number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '(s: string) => void'
     w=g;
     ~
 !!! error TS2322: Type '(s: string) => void' is not assignable to type '{ [x: number]: number; }'.
@@ -27,4 +32,5 @@ tests/cases/compiler/parseTypes.ts(12,1): error TS2322: Type '(s: string) => voi
     z=g;
     ~
 !!! error TS2322: Type '(s: string) => void' is not assignable to type 'new () => number'.
+!!! error TS2322:   Signature 'new (): number' has no corresponding signature in '(s: string) => void'
     
\ No newline at end of file
diff --git a/tests/baselines/reference/parser536727.errors.txt b/tests/baselines/reference/parser536727.errors.txt
index 4204e62c93b..70841efd89f 100644
--- a/tests/baselines/reference/parser536727.errors.txt
+++ b/tests/baselines/reference/parser536727.errors.txt
@@ -1,7 +1,9 @@
 tests/cases/conformance/parser/ecmascript5/RegressionTests/parser536727.ts(7,5): error TS2345: Argument of type '() => (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
-  Type '(x: string) => string' is not assignable to type 'string'.
+  Signature '(x: string): string' has no corresponding signature in '() => (x: string) => string'
+    Type '(x: string) => string' is not assignable to type 'string'.
 tests/cases/conformance/parser/ecmascript5/RegressionTests/parser536727.ts(8,5): error TS2345: Argument of type '() => (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
-  Type '(x: string) => string' is not assignable to type 'string'.
+  Signature '(x: string): string' has no corresponding signature in '() => (x: string) => string'
+    Type '(x: string) => string' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/RegressionTests/parser536727.ts (2 errors) ====
@@ -14,9 +16,11 @@ tests/cases/conformance/parser/ecmascript5/RegressionTests/parser536727.ts(8,5):
     foo(() => g);
         ~~~~~~~
 !!! error TS2345: Argument of type '() => (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
-!!! error TS2345:   Type '(x: string) => string' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in '() => (x: string) => string'
+!!! error TS2345:     Type '(x: string) => string' is not assignable to type 'string'.
     foo(x);
         ~
 !!! error TS2345: Argument of type '() => (x: string) => string' is not assignable to parameter of type '(x: string) => string'.
-!!! error TS2345:   Type '(x: string) => string' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(x: string): string' has no corresponding signature in '() => (x: string) => string'
+!!! error TS2345:     Type '(x: string) => string' is not assignable to type 'string'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/parserAutomaticSemicolonInsertion1.errors.txt b/tests/baselines/reference/parserAutomaticSemicolonInsertion1.errors.txt
index ee17b6f82aa..5eebe963b90 100644
--- a/tests/baselines/reference/parserAutomaticSemicolonInsertion1.errors.txt
+++ b/tests/baselines/reference/parserAutomaticSemicolonInsertion1.errors.txt
@@ -1,5 +1,7 @@
 tests/cases/conformance/parser/ecmascript5/AutomaticSemicolonInsertion/parserAutomaticSemicolonInsertion1.ts(8,1): error TS2322: Type 'Object' is not assignable to type 'I'.
+  Signature '(): void' has no corresponding signature in 'Object'
 tests/cases/conformance/parser/ecmascript5/AutomaticSemicolonInsertion/parserAutomaticSemicolonInsertion1.ts(14,1): error TS2322: Type 'Object' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in 'Object'
 
 
 ==== tests/cases/conformance/parser/ecmascript5/AutomaticSemicolonInsertion/parserAutomaticSemicolonInsertion1.ts (2 errors) ====
@@ -13,6 +15,7 @@ tests/cases/conformance/parser/ecmascript5/AutomaticSemicolonInsertion/parserAut
     i = o;
     ~
 !!! error TS2322: Type 'Object' is not assignable to type 'I'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Object'
      
     var a: {
         (): void
@@ -21,4 +24,5 @@ tests/cases/conformance/parser/ecmascript5/AutomaticSemicolonInsertion/parserAut
     a = o;
     ~
 !!! error TS2322: Type 'Object' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Object'
     
\ No newline at end of file
diff --git a/tests/baselines/reference/promiseChaining1.errors.txt b/tests/baselines/reference/promiseChaining1.errors.txt
index bd3e52fcc1c..da593b4086c 100644
--- a/tests/baselines/reference/promiseChaining1.errors.txt
+++ b/tests/baselines/reference/promiseChaining1.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/promiseChaining1.ts(7,50): error TS2345: Argument of type '(x: S) => string' is not assignable to parameter of type '(x: S) => Function'.
-  Type 'string' is not assignable to type 'Function'.
-    Property 'apply' is missing in type 'String'.
+  Signature '(x: S): Function' has no corresponding signature in '(x: S) => string'
+    Type 'string' is not assignable to type 'Function'.
+      Property 'apply' is missing in type 'String'.
 
 
 ==== tests/cases/compiler/promiseChaining1.ts (1 errors) ====
@@ -13,8 +14,9 @@ tests/cases/compiler/promiseChaining1.ts(7,50): error TS2345: Argument of type '
             var z = this.then(x => result)/*S*/.then(x => "abc")/*Function*/.then(x => x.length)/*number*/; // Should error on "abc" because it is not a Function
                                                      ~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: S) => string' is not assignable to parameter of type '(x: S) => Function'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Function'.
-!!! error TS2345:     Property 'apply' is missing in type 'String'.
+!!! error TS2345:   Signature '(x: S): Function' has no corresponding signature in '(x: S) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Function'.
+!!! error TS2345:       Property 'apply' is missing in type 'String'.
             return new Chain2(result);
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/promiseChaining2.errors.txt b/tests/baselines/reference/promiseChaining2.errors.txt
index f12baebd4dc..acdaad94bef 100644
--- a/tests/baselines/reference/promiseChaining2.errors.txt
+++ b/tests/baselines/reference/promiseChaining2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/promiseChaining2.ts(7,45): error TS2345: Argument of type '(x: S) => string' is not assignable to parameter of type '(x: S) => Function'.
-  Type 'string' is not assignable to type 'Function'.
-    Property 'apply' is missing in type 'String'.
+  Signature '(x: S): Function' has no corresponding signature in '(x: S) => string'
+    Type 'string' is not assignable to type 'Function'.
+      Property 'apply' is missing in type 'String'.
 
 
 ==== tests/cases/compiler/promiseChaining2.ts (1 errors) ====
@@ -13,8 +14,9 @@ tests/cases/compiler/promiseChaining2.ts(7,45): error TS2345: Argument of type '
             var z = this.then(x => result).then(x => "abc").then(x => x.length);
                                                 ~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: S) => string' is not assignable to parameter of type '(x: S) => Function'.
-!!! error TS2345:   Type 'string' is not assignable to type 'Function'.
-!!! error TS2345:     Property 'apply' is missing in type 'String'.
+!!! error TS2345:   Signature '(x: S): Function' has no corresponding signature in '(x: S) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'Function'.
+!!! error TS2345:       Property 'apply' is missing in type 'String'.
             return new Chain2(result);
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/promisePermutations.errors.txt b/tests/baselines/reference/promisePermutations.errors.txt
index a74938f5dd9..0787189e2e0 100644
--- a/tests/baselines/reference/promisePermutations.errors.txt
+++ b/tests/baselines/reference/promisePermutations.errors.txt
@@ -1,50 +1,75 @@
 tests/cases/compiler/promisePermutations.ts(74,70): error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'IPromise<number>'.
-      Property 'then' is missing in type 'Number'.
+  Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'IPromise<number>'.
+        Property 'then' is missing in type 'Number'.
 tests/cases/compiler/promisePermutations.ts(79,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(82,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(83,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(84,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(88,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations.ts(91,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations.ts(92,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations.ts(93,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations.ts(97,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations.ts(100,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations.ts(101,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations.ts(102,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations.ts(106,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(109,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(110,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(111,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(117,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations.ts(120,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations.ts(121,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations.ts(122,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations.ts(126,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations.ts(129,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations.ts(132,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations.ts(133,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations.ts(134,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations.ts(137,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
@@ -55,27 +80,35 @@ tests/cases/compiler/promisePermutations.ts(152,12): error TS2453: The type argu
   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Types of property 'then' are incompatible.
       Type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }' is not assignable to type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => Promise<any>'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'string' is not assignable to type 'number'.
+        Signature '<U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'
+          Types of parameters 'success' and 'success' are incompatible.
+            Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => Promise<any>'.
+              Signature '(value: number): Promise<any>' has no corresponding signature in '(value: string) => IPromise<any>'
+                Types of parameters 'value' and 'value' are incompatible.
+                  Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations.ts(156,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(158,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(159,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-    Types of property 'then' are incompatible.
-      Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => IPromise<any>'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+      Types of property 'then' are incompatible.
+        Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
+          Signature '<U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'
+            Types of parameters 'success' and 'success' are incompatible.
+              Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => IPromise<any>'.
+                Signature '(value: string): IPromise<any>' has no corresponding signature in '(value: number) => Promise<any>'
+                  Types of parameters 'value' and 'value' are incompatible.
+                    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/promisePermutations.ts (33 errors) ====
@@ -155,9 +188,10 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of t
     var s3d = s3.then(testFunction3P, testFunction3, testFunction3).then(testFunction3, testFunction3, testFunction3); // error
                                                                          ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'IPromise<number>'.
-!!! error TS2345:       Property 'then' is missing in type 'Number'.
+!!! error TS2345:   Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'IPromise<number>'.
+!!! error TS2345:         Property 'then' is missing in type 'Number'.
     
     var r4: IPromise<string>;
     var sIPromise: (x: any) => IPromise<string>;
@@ -165,84 +199,100 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of t
     var r4a = r4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var r4b = r4.then(sIPromise, testFunction4, testFunction4).then(sIPromise, testFunction4, testFunction4); // ok
     var s4: Promise<string>;
     var s4a = s4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4b = s4.then(testFunction4P, testFunction4P, testFunction4P); // error 
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4c = s4.then(testFunction4P, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4d = s4.then(sIPromise, testFunction4P, testFunction4).then(sIPromise, testFunction4P, testFunction4);
     
     var r5: IPromise<string>;
     var r5a = r5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var r5b = r5.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s5: Promise<string>;
     var s5a = s5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var s5b = s5.then(testFunction5P, testFunction5P, testFunction5P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5c = s5.then(testFunction5P, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5d = s5.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r6: IPromise<string>;
     var r6a = r6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var r6b = r6.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s6: Promise<string>;
     var s6a = s6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var s6b = s6.then(testFunction6P, testFunction6P, testFunction6P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6c = s6.then(testFunction6P, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6d = s6.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r7: IPromise<string>;
     var r7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var r7b = r7.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s7: Promise<string>;
     var s7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7b = r7.then(testFunction7P, testFunction7P, testFunction7P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7c = r7.then(testFunction7P, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7d = r7.then(sPromise, sPromise, sPromise).then(sPromise, sPromise, sPromise); // ok?
     
     var r8: IPromise<number>;
@@ -251,23 +301,28 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of t
     var r8a = r8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var r8b = r8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     var s8: Promise<number>;
     var s8a = s8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var s8b = s8.then(testFunction8P, testFunction8P, testFunction8P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8c = s8.then(testFunction8P, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8d = s8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     
     var r9: IPromise<number>;
     var r9a = r9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var r9b = r9.then(sIPromise, sIPromise, sIPromise); // ok
     var r9c = r9.then(nIPromise, nIPromise, nIPromise); // ok
     var r9d = r9.then(testFunction, sIPromise, nIPromise); // ok
@@ -280,12 +335,15 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of t
     var s9a = s9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var s9b = s9.then(testFunction9P, testFunction9P, testFunction9P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9c = s9.then(testFunction9P, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9d = s9.then(sPromise, sPromise, sPromise); // ok
     var s9e = s9.then(nPromise, nPromise, nPromise); // ok
     var s9f = s9.then(testFunction, sIPromise, nIPromise); // error
@@ -317,39 +375,47 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2345: Argument of t
 !!! error TS2453:   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
 !!! error TS2453:     Types of property 'then' are incompatible.
 !!! error TS2453:       Type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }' is not assignable to type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-!!! error TS2453:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2453:           Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => Promise<any>'.
-!!! error TS2453:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2453:               Type 'string' is not assignable to type 'number'.
+!!! error TS2453:         Signature '<U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'
+!!! error TS2453:           Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2453:             Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => Promise<any>'.
+!!! error TS2453:               Signature '(value: number): Promise<any>' has no corresponding signature in '(value: string) => IPromise<any>'
+!!! error TS2453:                 Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2453:                   Type 'string' is not assignable to type 'number'.
     var s10g = s10.then(testFunctionP, nIPromise, sIPromise).then(sPromise, sIPromise, sIPromise); // ok
     
     var r11: IPromise<number>;
     var r11a = r11.then(testFunction11, testFunction11, testFunction11); // error
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11: Promise<number>;
     var s11a = s11.then(testFunction11, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11b = s11.then(testFunction11P, testFunction11P, testFunction11P); // error
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11c = s11.then(testFunction11P, testFunction11, testFunction11); // error
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Types of property 'then' are incompatible.
-!!! error TS2345:       Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
-!!! error TS2345:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2345:           Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => IPromise<any>'.
-!!! error TS2345:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2345:               Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Types of property 'then' are incompatible.
+!!! error TS2345:         Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
+!!! error TS2345:           Signature '<U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'
+!!! error TS2345:             Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2345:               Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => IPromise<any>'.
+!!! error TS2345:                 Signature '(value: string): IPromise<any>' has no corresponding signature in '(value: number) => Promise<any>'
+!!! error TS2345:                   Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2345:                     Type 'number' is not assignable to type 'string'.
     
     var r12 = testFunction12(x => x);
     var r12a = r12.then(testFunction12, testFunction12, testFunction12); // ok
diff --git a/tests/baselines/reference/promisePermutations2.errors.txt b/tests/baselines/reference/promisePermutations2.errors.txt
index 8afceeae0fd..054cdec66c9 100644
--- a/tests/baselines/reference/promisePermutations2.errors.txt
+++ b/tests/baselines/reference/promisePermutations2.errors.txt
@@ -1,50 +1,75 @@
 tests/cases/compiler/promisePermutations2.ts(73,70): error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'IPromise<number>'.
-      Property 'then' is missing in type 'Number'.
+  Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'IPromise<number>'.
+        Property 'then' is missing in type 'Number'.
 tests/cases/compiler/promisePermutations2.ts(78,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(81,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(82,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(83,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(87,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations2.ts(90,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations2.ts(91,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations2.ts(92,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations2.ts(96,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations2.ts(99,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations2.ts(100,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations2.ts(101,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations2.ts(105,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(108,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(109,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(110,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(116,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations2.ts(119,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations2.ts(120,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations2.ts(121,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations2.ts(125,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations2.ts(128,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations2.ts(131,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations2.ts(132,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations2.ts(133,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations2.ts(136,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
@@ -55,27 +80,35 @@ tests/cases/compiler/promisePermutations2.ts(151,12): error TS2453: The type arg
   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Types of property 'then' are incompatible.
       Type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }' is not assignable to type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => any'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'string' is not assignable to type 'number'.
+        Signature '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'
+          Types of parameters 'success' and 'success' are incompatible.
+            Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => any'.
+              Signature '(value: number): any' has no corresponding signature in '(value: string) => IPromise<any>'
+                Types of parameters 'value' and 'value' are incompatible.
+                  Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations2.ts(155,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(157,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(158,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-    Types of property 'then' are incompatible.
-      Type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: number) => any' is not assignable to type '(value: string) => IPromise<any>'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+      Types of property 'then' are incompatible.
+        Type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
+          Signature '<U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>'
+            Types of parameters 'success' and 'success' are incompatible.
+              Type '(value: number) => any' is not assignable to type '(value: string) => IPromise<any>'.
+                Signature '(value: string): IPromise<any>' has no corresponding signature in '(value: number) => any'
+                  Types of parameters 'value' and 'value' are incompatible.
+                    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/promisePermutations2.ts (33 errors) ====
@@ -154,9 +187,10 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
     var s3d = s3.then(testFunction3P, testFunction3, testFunction3).then(testFunction3, testFunction3, testFunction3); // Should error
                                                                          ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'IPromise<number>'.
-!!! error TS2345:       Property 'then' is missing in type 'Number'.
+!!! error TS2345:   Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'IPromise<number>'.
+!!! error TS2345:         Property 'then' is missing in type 'Number'.
     
     var r4: IPromise<string>;
     var sIPromise: (x: any) => IPromise<string>;
@@ -164,84 +198,100 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
     var r4a = r4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var r4b = r4.then(sIPromise, testFunction4, testFunction4).then(sIPromise, testFunction4, testFunction4); // ok
     var s4: Promise<string>;
     var s4a = s4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4b = s4.then(testFunction4P, testFunction4P, testFunction4P); // error 
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4c = s4.then(testFunction4P, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4d = s4.then(sIPromise, testFunction4P, testFunction4).then(sIPromise, testFunction4P, testFunction4);
     
     var r5: IPromise<string>;
     var r5a = r5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var r5b = r5.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s5: Promise<string>;
     var s5a = s5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var s5b = s5.then(testFunction5P, testFunction5P, testFunction5P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5c = s5.then(testFunction5P, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5d = s5.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r6: IPromise<string>;
     var r6a = r6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var r6b = r6.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s6: Promise<string>;
     var s6a = s6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var s6b = s6.then(testFunction6P, testFunction6P, testFunction6P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6c = s6.then(testFunction6P, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6d = s6.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r7: IPromise<string>;
     var r7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var r7b = r7.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s7: Promise<string>;
     var s7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7b = r7.then(testFunction7P, testFunction7P, testFunction7P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7c = r7.then(testFunction7P, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7d = r7.then(sPromise, sPromise, sPromise).then(sPromise, sPromise, sPromise); // ok?
     
     var r8: IPromise<number>;
@@ -250,23 +300,28 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
     var r8a = r8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var r8b = r8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     var s8: Promise<number>;
     var s8a = s8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var s8b = s8.then(testFunction8P, testFunction8P, testFunction8P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8c = s8.then(testFunction8P, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8d = s8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     
     var r9: IPromise<number>;
     var r9a = r9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var r9b = r9.then(sIPromise, sIPromise, sIPromise); // ok
     var r9c = r9.then(nIPromise, nIPromise, nIPromise); // ok
     var r9d = r9.then(testFunction, sIPromise, nIPromise); // error
@@ -279,12 +334,15 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
     var s9a = s9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var s9b = s9.then(testFunction9P, testFunction9P, testFunction9P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9c = s9.then(testFunction9P, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9d = s9.then(sPromise, sPromise, sPromise); // ok
     var s9e = s9.then(nPromise, nPromise, nPromise); // ok
     var s9f = s9.then(testFunction, sIPromise, nIPromise); // error
@@ -316,39 +374,47 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
 !!! error TS2453:   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
 !!! error TS2453:     Types of property 'then' are incompatible.
 !!! error TS2453:       Type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }' is not assignable to type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>'.
-!!! error TS2453:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2453:           Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => any'.
-!!! error TS2453:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2453:               Type 'string' is not assignable to type 'number'.
+!!! error TS2453:         Signature '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'
+!!! error TS2453:           Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2453:             Type '(value: string) => IPromise<any>' is not assignable to type '(value: number) => any'.
+!!! error TS2453:               Signature '(value: number): any' has no corresponding signature in '(value: string) => IPromise<any>'
+!!! error TS2453:                 Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2453:                   Type 'string' is not assignable to type 'number'.
     var s10g = s10.then(testFunctionP, nIPromise, sIPromise).then(sPromise, sIPromise, sIPromise); // ok
     
     var r11: IPromise<number>;
     var r11a = r11.then(testFunction11, testFunction11, testFunction11); // error
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11: Promise<number>;
     var s11a = s11.then(testFunction11, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11b = s11.then(testFunction11P, testFunction11P, testFunction11P); // ok
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11c = s11.then(testFunction11P, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Types of property 'then' are incompatible.
-!!! error TS2345:       Type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
-!!! error TS2345:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2345:           Type '(value: number) => any' is not assignable to type '(value: string) => IPromise<any>'.
-!!! error TS2345:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2345:               Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Types of property 'then' are incompatible.
+!!! error TS2345:         Type '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
+!!! error TS2345:           Signature '<U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '<U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void) => Promise<U>'
+!!! error TS2345:             Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2345:               Type '(value: number) => any' is not assignable to type '(value: string) => IPromise<any>'.
+!!! error TS2345:                 Signature '(value: string): IPromise<any>' has no corresponding signature in '(value: number) => any'
+!!! error TS2345:                   Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2345:                     Type 'number' is not assignable to type 'string'.
     
     var r12 = testFunction12(x => x);
     var r12a = r12.then(testFunction12, testFunction12, testFunction12); // ok
diff --git a/tests/baselines/reference/promisePermutations3.errors.txt b/tests/baselines/reference/promisePermutations3.errors.txt
index b17021a02b9..5d414cf4176 100644
--- a/tests/baselines/reference/promisePermutations3.errors.txt
+++ b/tests/baselines/reference/promisePermutations3.errors.txt
@@ -1,53 +1,79 @@
 tests/cases/compiler/promisePermutations3.ts(68,69): error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'IPromise<number>'.
-      Property 'then' is missing in type 'Number'.
+  Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'IPromise<number>'.
+        Property 'then' is missing in type 'Number'.
 tests/cases/compiler/promisePermutations3.ts(73,70): error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'IPromise<number>'.
+  Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'IPromise<number>'.
 tests/cases/compiler/promisePermutations3.ts(78,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(81,19): error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(82,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(83,19): error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'x' and 'value' are incompatible.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+    Types of parameters 'x' and 'value' are incompatible.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(87,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations3.ts(90,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
 tests/cases/compiler/promisePermutations3.ts(91,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations3.ts(92,19): error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
 tests/cases/compiler/promisePermutations3.ts(96,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations3.ts(99,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
 tests/cases/compiler/promisePermutations3.ts(100,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations3.ts(101,19): error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
 tests/cases/compiler/promisePermutations3.ts(105,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(108,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(109,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(110,19): error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-  Types of parameters 'cb' and 'value' are incompatible.
-    Type '<T>(a: T) => T' is not assignable to type 'string'.
+  Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+    Types of parameters 'cb' and 'value' are incompatible.
+      Type '<T>(a: T) => T' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(116,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations3.ts(119,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
 tests/cases/compiler/promisePermutations3.ts(120,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations3.ts(121,19): error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
 tests/cases/compiler/promisePermutations3.ts(125,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations3.ts(128,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations3.ts(131,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+  Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
 tests/cases/compiler/promisePermutations3.ts(132,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+  Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations3.ts(133,19): error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+  Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
 tests/cases/compiler/promisePermutations3.ts(136,11): error TS2453: The type argument for type parameter 'U' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'IPromise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Type 'string' is not assignable to type 'number'.
@@ -58,32 +84,42 @@ tests/cases/compiler/promisePermutations3.ts(151,12): error TS2453: The type arg
   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
     Types of property 'then' are incompatible.
       Type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: string) => any' is not assignable to type '(value: number) => Promise<any>'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'string' is not assignable to type 'number'.
+        Signature '<U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'
+          Types of parameters 'success' and 'success' are incompatible.
+            Type '(value: string) => any' is not assignable to type '(value: number) => Promise<any>'.
+              Signature '(value: number): Promise<any>' has no corresponding signature in '(value: string) => any'
+                Types of parameters 'value' and 'value' are incompatible.
+                  Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/promisePermutations3.ts(155,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(157,21): error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+    Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(158,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-  Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-    Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+      Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(159,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-    Types of property 'then' are incompatible.
-      Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
-        Types of parameters 'success' and 'success' are incompatible.
-          Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => any'.
-            Types of parameters 'value' and 'value' are incompatible.
-              Type 'number' is not assignable to type 'string'.
+  Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+    Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+      Types of property 'then' are incompatible.
+        Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
+          Signature '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'
+            Types of parameters 'success' and 'success' are incompatible.
+              Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => any'.
+                Signature '(value: string): any' has no corresponding signature in '(value: number) => Promise<any>'
+                  Types of parameters 'value' and 'value' are incompatible.
+                    Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of type '{ <T>(x: T): IPromise<T>; <T>(x: T, y: T): Promise<T>; }' is not assignable to parameter of type '(value: (x: any) => any) => Promise<any>'.
-  Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
-    Types of property 'then' are incompatible.
-      Type '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-        Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
+  Signature '(value: (x: any) => any): Promise<any>' has no corresponding signature in '{ <T>(x: T): IPromise<T>; <T>(x: T, y: T): Promise<T>; }'
+    Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
+      Types of property 'then' are incompatible.
+        Type '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
+          Signature '<U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'
+            Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
 
 
 ==== tests/cases/compiler/promisePermutations3.ts (35 errors) ====
@@ -157,9 +193,10 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var r3b = r3.then(testFunction3, testFunction3, testFunction3).then(testFunction3, testFunction3, testFunction3);
                                                                         ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'IPromise<number>'.
-!!! error TS2345:       Property 'then' is missing in type 'Number'.
+!!! error TS2345:   Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'IPromise<number>'.
+!!! error TS2345:         Property 'then' is missing in type 'Number'.
     var s3: Promise<number>;
     var s3a = s3.then(testFunction3, testFunction3, testFunction3);
     var s3b = s3.then(testFunction3P, testFunction3P, testFunction3P);
@@ -167,8 +204,9 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var s3d = s3.then(testFunction3P, testFunction3, testFunction3).then(testFunction3, testFunction3, testFunction3);
                                                                          ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => IPromise<number>' is not assignable to parameter of type '(value: IPromise<number>) => IPromise<number>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'IPromise<number>'.
+!!! error TS2345:   Signature '(value: IPromise<number>): IPromise<number>' has no corresponding signature in '(x: number) => IPromise<number>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'IPromise<number>'.
     
     var r4: IPromise<string>;
     var sIPromise: (x: any) => IPromise<string>;
@@ -176,84 +214,100 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var r4a = r4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var r4b = r4.then(sIPromise, testFunction4, testFunction4).then(sIPromise, testFunction4, testFunction4); // ok
     var s4: Promise<string>;
     var s4a = s4.then(testFunction4, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4b = s4.then(testFunction4P, testFunction4P, testFunction4P); // error 
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4c = s4.then(testFunction4P, testFunction4, testFunction4); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, y?: string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'x' and 'value' are incompatible.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, y?: string) => Promise<string>'
+!!! error TS2345:     Types of parameters 'x' and 'value' are incompatible.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s4d = s4.then(sIPromise, testFunction4P, testFunction4).then(sIPromise, testFunction4P, testFunction4);
     
     var r5: IPromise<string>;
     var r5a = r5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var r5b = r5.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s5: Promise<string>;
     var s5a = s5.then(testFunction5, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => IPromise<string>'
     var s5b = s5.then(testFunction5P, testFunction5P, testFunction5P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5c = s5.then(testFunction5P, testFunction5, testFunction5); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: (a: string) => string) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: (a: string) => string) => Promise<string>'
     var s5d = s5.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r6: IPromise<string>;
     var r6a = r6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var r6b = r6.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s6: Promise<string>;
     var s6a = s6.then(testFunction6, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => IPromise<string>'
     var s6b = s6.then(testFunction6P, testFunction6P, testFunction6P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6c = s6.then(testFunction6P, testFunction6, testFunction6); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number, cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(x: number, cb: <T>(a: T) => T) => Promise<string>'
     var s6d = s6.then(sPromise, sPromise, sPromise).then(sIPromise, sIPromise, sIPromise); // ok
     
     var r7: IPromise<string>;
     var r7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var r7b = r7.then(sIPromise, sIPromise, sIPromise).then(sIPromise, sIPromise, sIPromise); // ok
     var s7: Promise<string>;
     var s7a = r7.then(testFunction7, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => IPromise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => IPromise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7b = r7.then(testFunction7P, testFunction7P, testFunction7P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => Promise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): Promise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7c = r7.then(testFunction7P, testFunction7, testFunction7); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(cb: <T>(a: T) => T) => Promise<string>' is not assignable to parameter of type '(value: string) => IPromise<string>'.
-!!! error TS2345:   Types of parameters 'cb' and 'value' are incompatible.
-!!! error TS2345:     Type '<T>(a: T) => T' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: string): IPromise<string>' has no corresponding signature in '(cb: <T>(a: T) => T) => Promise<string>'
+!!! error TS2345:     Types of parameters 'cb' and 'value' are incompatible.
+!!! error TS2345:       Type '<T>(a: T) => T' is not assignable to type 'string'.
     var s7d = r7.then(sPromise, sPromise, sPromise).then(sPromise, sPromise, sPromise); // ok?
     
     var r8: IPromise<number>;
@@ -262,23 +316,28 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var r8a = r8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var r8b = r8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     var s8: Promise<number>;
     var s8a = s8.then(testFunction8, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => IPromise<T>'
     var s8b = s8.then(testFunction8P, testFunction8P, testFunction8P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8c = s8.then(testFunction8P, testFunction8, testFunction8); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: (a: T) => T) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: (a: T) => T) => Promise<T>'
     var s8d = s8.then(nIPromise, nIPromise, nIPromise).then(nIPromise, nIPromise, nIPromise); // ok
     
     var r9: IPromise<number>;
     var r9a = r9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var r9b = r9.then(sIPromise, sIPromise, sIPromise); // ok
     var r9c = r9.then(nIPromise, nIPromise, nIPromise); // ok
     var r9d = r9.then(testFunction, sIPromise, nIPromise); // error
@@ -291,12 +350,15 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var s9a = s9.then(testFunction9, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>' is not assignable to parameter of type '(value: number) => IPromise<number>'.
+!!! error TS2345:   Signature '(value: number): IPromise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => IPromise<T>'
     var s9b = s9.then(testFunction9P, testFunction9P, testFunction9P); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => Promise<number>'.
+!!! error TS2345:   Signature '(value: number): Promise<number>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9c = s9.then(testFunction9P, testFunction9, testFunction9); // error
                       ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>' is not assignable to parameter of type '(value: number) => IPromise<any>'.
+!!! error TS2345:   Signature '(value: number): IPromise<any>' has no corresponding signature in '<T>(x: T, cb: <U>(a: U) => U) => Promise<T>'
     var s9d = s9.then(sPromise, sPromise, sPromise); // ok
     var s9e = s9.then(nPromise, nPromise, nPromise); // ok
     var s9f = s9.then(testFunction, sIPromise, nIPromise); // error
@@ -328,39 +390,47 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
 !!! error TS2453:   Type argument candidate 'Promise<number>' is not a valid type argument because it is not a supertype of candidate 'IPromise<string>'.
 !!! error TS2453:     Types of property 'then' are incompatible.
 !!! error TS2453:       Type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-!!! error TS2453:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2453:           Type '(value: string) => any' is not assignable to type '(value: number) => Promise<any>'.
-!!! error TS2453:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2453:               Type 'string' is not assignable to type 'number'.
+!!! error TS2453:         Signature '<U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'
+!!! error TS2453:           Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2453:             Type '(value: string) => any' is not assignable to type '(value: number) => Promise<any>'.
+!!! error TS2453:               Signature '(value: number): Promise<any>' has no corresponding signature in '(value: string) => any'
+!!! error TS2453:                 Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2453:                   Type 'string' is not assignable to type 'number'.
     var s10g = s10.then(testFunctionP, nIPromise, sIPromise).then(sPromise, sIPromise, sIPromise); // ok
     
     var r11: IPromise<number>;
     var r11a = r11.then(testFunction11, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11: Promise<number>;
     var s11a = s11.then(testFunction11, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): IPromise<number>; (x: string): IPromise<string>; }'
+!!! error TS2345:     Type 'IPromise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11b = s11.then(testFunction11P, testFunction11P, testFunction11P); // error
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => Promise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
-!!! error TS2345:     Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): Promise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'Promise<string>'.
+!!! error TS2345:       Type 'number' is not assignable to type 'string'.
     var s11c = s11.then(testFunction11P, testFunction11, testFunction11); // error
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Types of property 'then' are incompatible.
-!!! error TS2345:       Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
-!!! error TS2345:         Types of parameters 'success' and 'success' are incompatible.
-!!! error TS2345:           Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => any'.
-!!! error TS2345:             Types of parameters 'value' and 'value' are incompatible.
-!!! error TS2345:               Type 'number' is not assignable to type 'string'.
+!!! error TS2345:   Signature '(value: number): IPromise<string>' has no corresponding signature in '{ (x: number): Promise<number>; (x: string): Promise<string>; }'
+!!! error TS2345:     Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
+!!! error TS2345:       Types of property 'then' are incompatible.
+!!! error TS2345:         Type '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
+!!! error TS2345:           Signature '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>' has no corresponding signature in '{ <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'
+!!! error TS2345:             Types of parameters 'success' and 'success' are incompatible.
+!!! error TS2345:               Type '(value: number) => Promise<any>' is not assignable to type '(value: string) => any'.
+!!! error TS2345:                 Signature '(value: string): any' has no corresponding signature in '(value: number) => Promise<any>'
+!!! error TS2345:                   Types of parameters 'value' and 'value' are incompatible.
+!!! error TS2345:                     Type 'number' is not assignable to type 'string'.
     
     var r12 = testFunction12(x => x);
     var r12a = r12.then(testFunction12, testFunction12, testFunction12); // ok
@@ -369,8 +439,10 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
     var s12b = s12.then(testFunction12P, testFunction12P, testFunction12P); // ok
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ <T>(x: T): IPromise<T>; <T>(x: T, y: T): Promise<T>; }' is not assignable to parameter of type '(value: (x: any) => any) => Promise<any>'.
-!!! error TS2345:   Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
-!!! error TS2345:     Types of property 'then' are incompatible.
-!!! error TS2345:       Type '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
-!!! error TS2345:         Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
+!!! error TS2345:   Signature '(value: (x: any) => any): Promise<any>' has no corresponding signature in '{ <T>(x: T): IPromise<T>; <T>(x: T, y: T): Promise<T>; }'
+!!! error TS2345:     Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
+!!! error TS2345:       Types of property 'then' are incompatible.
+!!! error TS2345:         Type '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>' is not assignable to type '{ <U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }'.
+!!! error TS2345:           Signature '<U>(success?: (value: any) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>' has no corresponding signature in '<U>(success?: (value: any) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'
+!!! error TS2345:             Type 'IPromise<any>' is not assignable to type 'Promise<any>'.
     var s12c = s12.then(testFunction12P, testFunction12, testFunction12); // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/propertyAssignment.errors.txt b/tests/baselines/reference/propertyAssignment.errors.txt
index 47359caf9c2..ae65ed9b73a 100644
--- a/tests/baselines/reference/propertyAssignment.errors.txt
+++ b/tests/baselines/reference/propertyAssignment.errors.txt
@@ -1,7 +1,9 @@
 tests/cases/compiler/propertyAssignment.ts(6,13): error TS1170: A computed property name in a type literal must directly refer to a built-in symbol.
 tests/cases/compiler/propertyAssignment.ts(6,14): error TS2304: Cannot find name 'index'.
 tests/cases/compiler/propertyAssignment.ts(14,1): error TS2322: Type '{ x: number; }' is not assignable to type 'new () => any'.
+  Signature 'new (): any' has no corresponding signature in '{ x: number; }'
 tests/cases/compiler/propertyAssignment.ts(16,1): error TS2322: Type '{ x: number; }' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in '{ x: number; }'
 
 
 ==== tests/cases/compiler/propertyAssignment.ts (4 errors) ====
@@ -25,7 +27,9 @@ tests/cases/compiler/propertyAssignment.ts(16,1): error TS2322: Type '{ x: numbe
     foo1 = bar1; // should be an error
     ~~~~
 !!! error TS2322: Type '{ x: number; }' is not assignable to type 'new () => any'.
+!!! error TS2322:   Signature 'new (): any' has no corresponding signature in '{ x: number; }'
     foo2 = bar2; 
     foo3 = bar3; // should be an error
     ~~~~
-!!! error TS2322: Type '{ x: number; }' is not assignable to type '() => void'.
\ No newline at end of file
+!!! error TS2322: Type '{ x: number; }' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in '{ x: number; }'
\ No newline at end of file
diff --git a/tests/baselines/reference/qualify.errors.txt b/tests/baselines/reference/qualify.errors.txt
index c7679a0a0f8..822b329b757 100644
--- a/tests/baselines/reference/qualify.errors.txt
+++ b/tests/baselines/reference/qualify.errors.txt
@@ -7,7 +7,9 @@ tests/cases/compiler/qualify.ts(45,13): error TS2322: Type 'I4' is not assignabl
 tests/cases/compiler/qualify.ts(46,13): error TS2322: Type 'I4' is not assignable to type 'I3[]'.
   Property 'length' is missing in type 'I4'.
 tests/cases/compiler/qualify.ts(47,13): error TS2322: Type 'I4' is not assignable to type '() => I3'.
+  Signature '(): I3' has no corresponding signature in 'I4'
 tests/cases/compiler/qualify.ts(48,13): error TS2322: Type 'I4' is not assignable to type '(k: I3) => void'.
+  Signature '(k: I3): void' has no corresponding signature in 'I4'
 tests/cases/compiler/qualify.ts(49,13): error TS2322: Type 'I4' is not assignable to type '{ k: I3; }'.
   Property 'k' is missing in type 'I4'.
 tests/cases/compiler/qualify.ts(58,5): error TS2322: Type 'I' is not assignable to type 'T.I'.
@@ -76,9 +78,11 @@ tests/cases/compiler/qualify.ts(58,5): error TS2322: Type 'I' is not assignable
             var v4:()=>K1.I3=v1;
                 ~~
 !!! error TS2322: Type 'I4' is not assignable to type '() => I3'.
+!!! error TS2322:   Signature '(): I3' has no corresponding signature in 'I4'
             var v5:(k:K1.I3)=>void=v1;
                 ~~
 !!! error TS2322: Type 'I4' is not assignable to type '(k: I3) => void'.
+!!! error TS2322:   Signature '(k: I3): void' has no corresponding signature in 'I4'
             var v6:{k:K1.I3;}=v1;
                 ~~
 !!! error TS2322: Type 'I4' is not assignable to type '{ k: I3; }'.
diff --git a/tests/baselines/reference/recursiveFunctionTypes.errors.txt b/tests/baselines/reference/recursiveFunctionTypes.errors.txt
index 8d5303c0669..9bc82f92ff3 100644
--- a/tests/baselines/reference/recursiveFunctionTypes.errors.txt
+++ b/tests/baselines/reference/recursiveFunctionTypes.errors.txt
@@ -1,23 +1,30 @@
 tests/cases/compiler/recursiveFunctionTypes.ts(1,35): error TS2322: Type 'number' is not assignable to type '() => typeof fn'.
+  Signature '(): () => typeof fn' has no corresponding signature in 'Number'
 tests/cases/compiler/recursiveFunctionTypes.ts(3,5): error TS2322: Type '() => typeof fn' is not assignable to type 'number'.
 tests/cases/compiler/recursiveFunctionTypes.ts(4,5): error TS2322: Type '() => typeof fn' is not assignable to type '() => number'.
-  Type '() => typeof fn' is not assignable to type 'number'.
+  Signature '(): number' has no corresponding signature in '() => typeof fn'
+    Type '() => typeof fn' is not assignable to type 'number'.
 tests/cases/compiler/recursiveFunctionTypes.ts(11,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/recursiveFunctionTypes.ts(12,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/recursiveFunctionTypes.ts(17,5): error TS2322: Type '() => I<typeof f3>' is not assignable to type 'number'.
 tests/cases/compiler/recursiveFunctionTypes.ts(22,5): error TS2345: Argument of type 'number' is not assignable to parameter of type '(t: typeof g) => void'.
+  Signature '(t: (t: typeof g) => void): void' has no corresponding signature in 'Number'
 tests/cases/compiler/recursiveFunctionTypes.ts(25,1): error TS2322: Type 'number' is not assignable to type '() => any'.
+  Signature '(): () => any' has no corresponding signature in 'Number'
 tests/cases/compiler/recursiveFunctionTypes.ts(30,10): error TS2394: Overload signature is not compatible with function implementation.
 tests/cases/compiler/recursiveFunctionTypes.ts(33,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/recursiveFunctionTypes.ts(34,4): error TS2345: Argument of type 'string' is not assignable to parameter of type '{ (): typeof f6; (a: typeof f6): () => number; }'.
+  Signature '(): { (): typeof f6; (a: typeof f6): () => number; }' has no corresponding signature in 'String'
 tests/cases/compiler/recursiveFunctionTypes.ts(42,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of type 'string' is not assignable to parameter of type '{ (): typeof f7; (a: typeof f7): () => number; (a: number): number; (a?: typeof f7): typeof f7; }'.
+  Signature '(): { (): typeof f7; (a: typeof f7): () => number; (a: number): number; (a?: typeof f7): typeof f7; }' has no corresponding signature in 'String'
 
 
 ==== tests/cases/compiler/recursiveFunctionTypes.ts (13 errors) ====
     function fn(): typeof fn { return 1; }
                                       ~
 !!! error TS2322: Type 'number' is not assignable to type '() => typeof fn'.
+!!! error TS2322:   Signature '(): () => typeof fn' has no corresponding signature in 'Number'
     
     var x: number = fn; // error
         ~
@@ -25,7 +32,8 @@ tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of
     var y: () => number = fn; // ok
         ~
 !!! error TS2322: Type '() => typeof fn' is not assignable to type '() => number'.
-!!! error TS2322:   Type '() => typeof fn' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(): number' has no corresponding signature in '() => typeof fn'
+!!! error TS2322:     Type '() => typeof fn' is not assignable to type 'number'.
     
     var f: () => typeof g;
     var g: () => typeof f;
@@ -52,11 +60,13 @@ tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of
     C.g(3); // error
         ~
 !!! error TS2345: Argument of type 'number' is not assignable to parameter of type '(t: typeof g) => void'.
+!!! error TS2345:   Signature '(t: (t: typeof g) => void): void' has no corresponding signature in 'Number'
     
     var f4: () => typeof f4;
     f4 = 3; // error
     ~~
 !!! error TS2322: Type 'number' is not assignable to type '() => any'.
+!!! error TS2322:   Signature '(): () => any' has no corresponding signature in 'Number'
     
     function f5() { return f5; }
     
@@ -72,6 +82,7 @@ tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of
     f6(""); // ok (function takes an any param)
        ~~
 !!! error TS2345: Argument of type 'string' is not assignable to parameter of type '{ (): typeof f6; (a: typeof f6): () => number; }'.
+!!! error TS2345:   Signature '(): { (): typeof f6; (a: typeof f6): () => number; }' has no corresponding signature in 'String'
     f6(); // ok
     
     declare function f7(): typeof f7;
@@ -85,4 +96,5 @@ tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of
     f7(""); // ok (function takes an any param)
        ~~
 !!! error TS2345: Argument of type 'string' is not assignable to parameter of type '{ (): typeof f7; (a: typeof f7): () => number; (a: number): number; (a?: typeof f7): typeof f7; }'.
+!!! error TS2345:   Signature '(): { (): typeof f7; (a: typeof f7): () => number; (a: number): number; (a?: typeof f7): typeof f7; }' has no corresponding signature in 'String'
     f7(); // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/requiredInitializedParameter2.errors.txt b/tests/baselines/reference/requiredInitializedParameter2.errors.txt
index 5dcec536e1b..493f9e49f23 100644
--- a/tests/baselines/reference/requiredInitializedParameter2.errors.txt
+++ b/tests/baselines/reference/requiredInitializedParameter2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/requiredInitializedParameter2.ts(5,7): error TS2420: Class 'C1' incorrectly implements interface 'I1'.
   Types of property 'method' are incompatible.
     Type '(a: number, b: any) => void' is not assignable to type '() => any'.
+      Signature '(): any' has no corresponding signature in '(a: number, b: any) => void'
 
 
 ==== tests/cases/compiler/requiredInitializedParameter2.ts (1 errors) ====
@@ -13,5 +14,6 @@ tests/cases/compiler/requiredInitializedParameter2.ts(5,7): error TS2420: Class
 !!! error TS2420: Class 'C1' incorrectly implements interface 'I1'.
 !!! error TS2420:   Types of property 'method' are incompatible.
 !!! error TS2420:     Type '(a: number, b: any) => void' is not assignable to type '() => any'.
+!!! error TS2420:       Signature '(): any' has no corresponding signature in '(a: number, b: any) => void'
         method(a = 0, b) { }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/restArgAssignmentCompat.errors.txt b/tests/baselines/reference/restArgAssignmentCompat.errors.txt
index 2ea07395099..cf6c70b58f3 100644
--- a/tests/baselines/reference/restArgAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/restArgAssignmentCompat.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/compiler/restArgAssignmentCompat.ts(7,1): error TS2322: Type '(...x: number[]) => void' is not assignable to type '(x: number[], y: string) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'number' is not assignable to type 'number[]'.
-      Property 'length' is missing in type 'Number'.
+  Signature '(x: number[], y: string): void' has no corresponding signature in '(...x: number[]) => void'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'number' is not assignable to type 'number[]'.
+        Property 'length' is missing in type 'Number'.
 
 
 ==== tests/cases/compiler/restArgAssignmentCompat.ts (1 errors) ====
@@ -14,8 +15,9 @@ tests/cases/compiler/restArgAssignmentCompat.ts(7,1): error TS2322: Type '(...x:
     n = f;
     ~
 !!! error TS2322: Type '(...x: number[]) => void' is not assignable to type '(x: number[], y: string) => void'.
-!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'number[]'.
-!!! error TS2322:       Property 'length' is missing in type 'Number'.
+!!! error TS2322:   Signature '(x: number[], y: string): void' has no corresponding signature in '(...x: number[]) => void'
+!!! error TS2322:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'number[]'.
+!!! error TS2322:         Property 'length' is missing in type 'Number'.
     n([4], 'foo');
     
\ No newline at end of file
diff --git a/tests/baselines/reference/staticMemberAssignsToConstructorFunctionMembers.errors.txt b/tests/baselines/reference/staticMemberAssignsToConstructorFunctionMembers.errors.txt
index db23c2a19f6..f490027f870 100644
--- a/tests/baselines/reference/staticMemberAssignsToConstructorFunctionMembers.errors.txt
+++ b/tests/baselines/reference/staticMemberAssignsToConstructorFunctionMembers.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclarations/staticMemberAssignsToConstructorFunctionMembers.ts(7,9): error TS2322: Type '() => void' is not assignable to type '(x: number) => number'.
-  Type 'void' is not assignable to type 'number'.
+  Signature '(x: number): number' has no corresponding signature in '() => void'
+    Type 'void' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclarations/staticMemberAssignsToConstructorFunctionMembers.ts (1 errors) ====
@@ -12,7 +13,8 @@ tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclara
             C.bar = () => { } // error
             ~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type '(x: number) => number'.
-!!! error TS2322:   Type 'void' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(x: number): number' has no corresponding signature in '() => void'
+!!! error TS2322:     Type 'void' is not assignable to type 'number'.
             C.bar = (x) => x; // ok
             C.bar = (x: number) => 1; // ok
             return 1;
diff --git a/tests/baselines/reference/stringLiteralTypesAsTypeParameterConstraint02.errors.txt b/tests/baselines/reference/stringLiteralTypesAsTypeParameterConstraint02.errors.txt
index ed6450ad329..aee87f77764 100644
--- a/tests/baselines/reference/stringLiteralTypesAsTypeParameterConstraint02.errors.txt
+++ b/tests/baselines/reference/stringLiteralTypesAsTypeParameterConstraint02.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/types/stringLiteral/stringLiteralTypesAsTypeParameterConstraint02.ts(6,13): error TS2345: Argument of type '(y: "foo" | "bar") => string' is not assignable to parameter of type '(x: "foo") => "foo"'.
-  Type 'string' is not assignable to type '"foo"'.
+  Signature '(x: "foo"): "foo"' has no corresponding signature in '(y: "foo" | "bar") => string'
+    Type 'string' is not assignable to type '"foo"'.
 
 
 ==== tests/cases/conformance/types/stringLiteral/stringLiteralTypesAsTypeParameterConstraint02.ts (1 errors) ====
@@ -11,5 +12,6 @@ tests/cases/conformance/types/stringLiteral/stringLiteralTypesAsTypeParameterCon
     let f = foo((y: "foo" | "bar") => y === "foo" ? y : "foo");
                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(y: "foo" | "bar") => string' is not assignable to parameter of type '(x: "foo") => "foo"'.
-!!! error TS2345:   Type 'string' is not assignable to type '"foo"'.
+!!! error TS2345:   Signature '(x: "foo"): "foo"' has no corresponding signature in '(y: "foo" | "bar") => string'
+!!! error TS2345:     Type 'string' is not assignable to type '"foo"'.
     let fResult = f("foo");
\ No newline at end of file
diff --git a/tests/baselines/reference/subtypingWithCallSignaturesA.errors.txt b/tests/baselines/reference/subtypingWithCallSignaturesA.errors.txt
index 3821c707f4b..24caddf4849 100644
--- a/tests/baselines/reference/subtypingWithCallSignaturesA.errors.txt
+++ b/tests/baselines/reference/subtypingWithCallSignaturesA.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesA.ts(2,15): error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => number'.
-  Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): number' has no corresponding signature in '(x: number) => string'
+    Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesA.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
     var r5 = foo3((x: number) => ''); // error
                   ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: number) => string' is not assignable to parameter of type '(x: number) => number'.
-!!! error TS2345:   Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2345:   Signature '(x: number): number' has no corresponding signature in '(x: number) => string'
+!!! error TS2345:     Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/subtypingWithCallSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithCallSignaturesWithOptionalParameters.errors.txt
index b5d23da2241..1ae866d4722 100644
--- a/tests/baselines/reference/subtypingWithCallSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithCallSignaturesWithOptionalParameters.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithOptionalParameters.ts(19,11): error TS2430: Interface 'I3' incorrectly extends interface 'Base'.
   Types of property 'a' are incompatible.
     Type '(x: number) => number' is not assignable to type '() => number'.
+      Signature '(): number' has no corresponding signature in '(x: number) => number'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithOptionalParameters.ts(49,11): error TS2430: Interface 'I10' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+      Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithOptionalParameters.ts (2 errors) ====
@@ -30,6 +32,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x: number) => number' is not assignable to type '() => number'.
+!!! error TS2430:       Signature '(): number' has no corresponding signature in '(x: number) => number'
         a: (x: number) => number; // error, too many required params
     }
     
@@ -64,6 +67,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: number, y: number) => number' is not assignable to type '(x: number) => number'.
+!!! error TS2430:       Signature '(x: number): number' has no corresponding signature in '(x: number, y: number) => number'
         a3: (x: number, y: number) => number;  // error, too many required params
     }
     
diff --git a/tests/baselines/reference/subtypingWithCallSignaturesWithRestParameters.errors.txt b/tests/baselines/reference/subtypingWithCallSignaturesWithRestParameters.errors.txt
index f4a141ff390..aee119d6f73 100644
--- a/tests/baselines/reference/subtypingWithCallSignaturesWithRestParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithCallSignaturesWithRestParameters.errors.txt
@@ -1,58 +1,69 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(18,11): error TS2430: Interface 'I1C' incorrectly extends interface 'Base'.
   Types of property 'a' are incompatible.
     Type '(...args: string[]) => number' is not assignable to type '(...args: number[]) => number'.
-      Types of parameters 'args' and 'args' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(...args: number[]): number' has no corresponding signature in '(...args: string[]) => number'
+        Types of parameters 'args' and 'args' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(34,11): error TS2430: Interface 'I3B' incorrectly extends interface 'Base'.
   Types of property 'a' are incompatible.
     Type '(x?: string) => number' is not assignable to type '(...args: number[]) => number'.
-      Types of parameters 'x' and 'args' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(...args: number[]): number' has no corresponding signature in '(x?: string) => number'
+        Types of parameters 'x' and 'args' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(60,11): error TS2430: Interface 'I6C' incorrectly extends interface 'Base'.
   Types of property 'a2' are incompatible.
     Type '(x: number, ...args: string[]) => number' is not assignable to type '(x: number, ...z: number[]) => number'.
-      Types of parameters 'args' and 'z' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+        Types of parameters 'args' and 'z' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(90,11): error TS2430: Interface 'I10B' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type '(x: number, y?: number, z?: number) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number, z?: number) => number'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(94,11): error TS2430: Interface 'I10C' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type '(x: number, ...z: number[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'z' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: number[]) => number'
+        Types of parameters 'z' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(98,11): error TS2430: Interface 'I10D' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type '(x: string, y?: string, z?: string) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'x' and 'x' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: string, y?: string, z?: string) => number'
+        Types of parameters 'x' and 'x' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(102,11): error TS2430: Interface 'I10E' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type '(x: number, ...z: string[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'z' and 'z' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: string[]) => number'
+        Types of parameters 'z' and 'z' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(110,11): error TS2430: Interface 'I12' incorrectly extends interface 'Base'.
   Types of property 'a4' are incompatible.
     Type '(x?: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x?: number, y?: number) => number'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(118,11): error TS2430: Interface 'I14' incorrectly extends interface 'Base'.
   Types of property 'a4' are incompatible.
     Type '(x: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'y' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number) => number'
+        Types of parameters 'y' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(126,11): error TS2430: Interface 'I16' incorrectly extends interface 'Base'.
   Types of property 'a4' are incompatible.
     Type '(x: number, ...args: string[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'args' and 'z' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+        Types of parameters 'args' and 'z' are incompatible.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts(130,11): error TS2430: Interface 'I17' incorrectly extends interface 'Base'.
   Types of property 'a4' are incompatible.
     Type '(...args: number[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-      Types of parameters 'args' and 'y' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+      Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(...args: number[]) => number'
+        Types of parameters 'args' and 'y' are incompatible.
+          Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithRestParameters.ts (11 errors) ====
@@ -78,8 +89,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I1C' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(...args: string[]) => number' is not assignable to type '(...args: number[]) => number'.
-!!! error TS2430:       Types of parameters 'args' and 'args' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(...args: number[]): number' has no corresponding signature in '(...args: string[]) => number'
+!!! error TS2430:         Types of parameters 'args' and 'args' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a: (...args: string[]) => number; // error, type mismatch
     }
     
@@ -100,8 +112,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3B' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x?: string) => number' is not assignable to type '(...args: number[]) => number'.
-!!! error TS2430:       Types of parameters 'x' and 'args' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(...args: number[]): number' has no corresponding signature in '(x?: string) => number'
+!!! error TS2430:         Types of parameters 'x' and 'args' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a: (x?: string) => number; // error, incompatible type
     }
     
@@ -132,8 +145,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I6C' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a2' are incompatible.
 !!! error TS2430:     Type '(x: number, ...args: string[]) => number' is not assignable to type '(x: number, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'args' and 'z' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: number, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+!!! error TS2430:         Types of parameters 'args' and 'z' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a2: (x: number, ...args: string[]) => number; // error
     }
     
@@ -168,8 +182,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10B' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: number, y?: number, z?: number) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number, z?: number) => number'
+!!! error TS2430:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2430:           Type 'number' is not assignable to type 'string'.
         a3: (x: number, y?: number, z?: number) => number;  // error
     }
     
@@ -178,8 +193,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10C' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: number, ...z: number[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'z' and 'y' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: number[]) => number'
+!!! error TS2430:         Types of parameters 'z' and 'y' are incompatible.
+!!! error TS2430:           Type 'number' is not assignable to type 'string'.
         a3: (x: number, ...z: number[]) => number;  // error
     }
     
@@ -188,8 +204,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10D' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: string, y?: string, z?: string) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: string, y?: string, z?: string) => number'
+!!! error TS2430:         Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a3: (x: string, y?: string, z?: string) => number;  // error, incompatible types
     }
     
@@ -198,8 +215,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10E' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: number, ...z: string[]) => number' is not assignable to type '(x: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'z' and 'z' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...z: string[]) => number'
+!!! error TS2430:         Types of parameters 'z' and 'z' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a3: (x: number, ...z: string[]) => number;  // error
     }
     
@@ -212,8 +230,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I12' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a4' are incompatible.
 !!! error TS2430:     Type '(x?: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x?: number, y?: number) => number'
+!!! error TS2430:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2430:           Type 'number' is not assignable to type 'string'.
         a4: (x?: number, y?: number) => number; // error, type mismatch
     }
     
@@ -226,8 +245,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I14' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a4' are incompatible.
 !!! error TS2430:     Type '(x: number, y?: number) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'y' and 'y' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, y?: number) => number'
+!!! error TS2430:         Types of parameters 'y' and 'y' are incompatible.
+!!! error TS2430:           Type 'number' is not assignable to type 'string'.
         a4: (x: number, y?: number) => number;  // error, second param has type mismatch
     }
     
@@ -240,8 +260,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I16' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a4' are incompatible.
 !!! error TS2430:     Type '(x: number, ...args: string[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'args' and 'z' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(x: number, ...args: string[]) => number'
+!!! error TS2430:         Types of parameters 'args' and 'z' are incompatible.
+!!! error TS2430:           Type 'string' is not assignable to type 'number'.
         a4: (x: number, ...args: string[]) => number;  // error, rest param has type mismatch
     }
     
@@ -250,8 +271,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I17' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a4' are incompatible.
 !!! error TS2430:     Type '(...args: number[]) => number' is not assignable to type '(x?: number, y?: string, ...z: number[]) => number'.
-!!! error TS2430:       Types of parameters 'args' and 'y' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:       Signature '(x?: number, y?: string, ...z: number[]): number' has no corresponding signature in '(...args: number[]) => number'
+!!! error TS2430:         Types of parameters 'args' and 'y' are incompatible.
+!!! error TS2430:           Type 'number' is not assignable to type 'string'.
         a4: (...args: number[]) => number; // error
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt b/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
index da742fcd69c..54eec881c14 100644
--- a/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
+++ b/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithSpecializedSignatures.ts(70,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type '(x: string) => string' is not assignable to type '{ (x: "a"): number; (x: string): number; }'.
-      Type 'string' is not assignable to type 'number'.
+      Signature '(x: string): number' has no corresponding signature in '(x: string) => string'
+        Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithSpecializedSignatures.ts (1 errors) ====
@@ -79,7 +80,8 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x: string) => string' is not assignable to type '{ (x: "a"): number; (x: string): number; }'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature '(x: string): number' has no corresponding signature in '(x: string) => string'
+!!! error TS2430:         Type 'string' is not assignable to type 'number'.
             // N's
             a: (x: string) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/subtypingWithConstructSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithConstructSignaturesWithOptionalParameters.errors.txt
index e041b1cdce0..a30feba51c9 100644
--- a/tests/baselines/reference/subtypingWithConstructSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithConstructSignaturesWithOptionalParameters.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithOptionalParameters.ts(19,11): error TS2430: Interface 'I3' incorrectly extends interface 'Base'.
   Types of property 'a' are incompatible.
     Type 'new (x: number) => number' is not assignable to type 'new () => number'.
+      Signature 'new (): number' has no corresponding signature in 'new (x: number) => number'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithOptionalParameters.ts(49,11): error TS2430: Interface 'I10' incorrectly extends interface 'Base'.
   Types of property 'a3' are incompatible.
     Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
+      Signature 'new (x: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithOptionalParameters.ts (2 errors) ====
@@ -30,6 +32,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new (x: number) => number' is not assignable to type 'new () => number'.
+!!! error TS2430:       Signature 'new (): number' has no corresponding signature in 'new (x: number) => number'
         a: new (x: number) => number; // error, too many required params
     }
     
@@ -64,6 +67,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type 'new (x: number, y: number) => number' is not assignable to type 'new (x: number) => number'.
+!!! error TS2430:       Signature 'new (x: number): number' has no corresponding signature in 'new (x: number, y: number) => number'
         a3: new (x: number, y: number) => number;  // error, too many required params
     }
     
diff --git a/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt b/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
index 8a885a2455f..fd9e6faa9ec 100644
--- a/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
+++ b/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithSpecializedSignatures.ts(70,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type 'new (x: string) => string' is not assignable to type '{ new (x: "a"): number; new (x: string): number; }'.
-      Type 'string' is not assignable to type 'number'.
+      Signature 'new (x: string): number' has no corresponding signature in 'new (x: string) => string'
+        Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithSpecializedSignatures.ts (1 errors) ====
@@ -79,7 +80,8 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new (x: string) => string' is not assignable to type '{ new (x: "a"): number; new (x: string): number; }'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:       Signature 'new (x: string): number' has no corresponding signature in 'new (x: string) => string'
+!!! error TS2430:         Type 'string' is not assignable to type 'number'.
             // N's
             a: new (x: string) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
index e8f50236cba..316b5713835 100644
--- a/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
@@ -1,21 +1,27 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(20,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base<T>'.
   Types of property 'a' are incompatible.
     Type '(x: T) => T' is not assignable to type '() => T'.
+      Signature '(): T' has no corresponding signature in '(x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(50,15): error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base<T>'.
   Types of property 'a3' are incompatible.
     Type '(x: T, y: T) => T' is not assignable to type '(x: T) => T'.
+      Signature '(x: T): T' has no corresponding signature in '(x: T, y: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(108,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type '(x: T) => T' is not assignable to type '<T>() => T'.
+      Signature '<T>(): T' has no corresponding signature in '(x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(138,15): error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type '(x: T, y: T) => T' is not assignable to type '<T>(x: T) => T'.
+      Signature '<T>(x: T): T' has no corresponding signature in '(x: T, y: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(196,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type '<T>(x: T) => T' is not assignable to type '<T>() => T'.
+      Signature '<T>(): T' has no corresponding signature in '<T>(x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(226,15): error TS2430: Interface 'I10' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type '<T>(x: T, y: T) => T' is not assignable to type '<T>(x: T) => T'.
+      Signature '<T>(x: T): T' has no corresponding signature in '<T>(x: T, y: T) => T'
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts (6 errors) ====
@@ -43,6 +49,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base<T>'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x: T) => T' is not assignable to type '() => T'.
+!!! error TS2430:       Signature '(): T' has no corresponding signature in '(x: T) => T'
             a: (x: T) => T; // error, too many required params
         }
     
@@ -77,6 +84,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base<T>'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: T, y: T) => T' is not assignable to type '(x: T) => T'.
+!!! error TS2430:       Signature '(x: T): T' has no corresponding signature in '(x: T, y: T) => T'
             a3: (x: T, y: T) => T;  // error, too many required params
         }
     
@@ -139,6 +147,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '(x: T) => T' is not assignable to type '<T>() => T'.
+!!! error TS2430:       Signature '<T>(): T' has no corresponding signature in '(x: T) => T'
             a: (x: T) => T; 
         }
     
@@ -173,6 +182,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '(x: T, y: T) => T' is not assignable to type '<T>(x: T) => T'.
+!!! error TS2430:       Signature '<T>(x: T): T' has no corresponding signature in '(x: T, y: T) => T'
             a3: (x: T, y: T) => T;  
         }
     
@@ -235,6 +245,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type '<T>(x: T) => T' is not assignable to type '<T>() => T'.
+!!! error TS2430:       Signature '<T>(): T' has no corresponding signature in '<T>(x: T) => T'
             a: <T>(x: T) => T; // error, not identical and contextual signature instatiation can't make inference from T to T
         }
     
@@ -269,6 +280,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type '<T>(x: T, y: T) => T' is not assignable to type '<T>(x: T) => T'.
+!!! error TS2430:       Signature '<T>(x: T): T' has no corresponding signature in '<T>(x: T, y: T) => T'
             a3: <T>(x: T, y: T) => T;  // error, too many required params
         }
     
diff --git a/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
index 27066058238..66dd34f9cb6 100644
--- a/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
@@ -1,21 +1,27 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(20,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base<T>'.
   Types of property 'a' are incompatible.
     Type 'new (x: T) => T' is not assignable to type 'new () => T'.
+      Signature 'new (): T' has no corresponding signature in 'new (x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(50,15): error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base<T>'.
   Types of property 'a3' are incompatible.
     Type 'new (x: T, y: T) => T' is not assignable to type 'new (x: T) => T'.
+      Signature 'new (x: T): T' has no corresponding signature in 'new (x: T, y: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(108,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type 'new (x: T) => T' is not assignable to type 'new <T>() => T'.
+      Signature 'new <T>(): T' has no corresponding signature in 'new (x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(138,15): error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type 'new (x: T, y: T) => T' is not assignable to type 'new <T>(x: T) => T'.
+      Signature 'new <T>(x: T): T' has no corresponding signature in 'new (x: T, y: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(196,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type 'new <T>(x: T) => T' is not assignable to type 'new <T>() => T'.
+      Signature 'new <T>(): T' has no corresponding signature in 'new <T>(x: T) => T'
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(226,15): error TS2430: Interface 'I10' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type 'new <T>(x: T, y: T) => T' is not assignable to type 'new <T>(x: T) => T'.
+      Signature 'new <T>(x: T): T' has no corresponding signature in 'new <T>(x: T, y: T) => T'
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts (6 errors) ====
@@ -43,6 +49,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base<T>'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new (x: T) => T' is not assignable to type 'new () => T'.
+!!! error TS2430:       Signature 'new (): T' has no corresponding signature in 'new (x: T) => T'
             a: new (x: T) => T; // error, too many required params
         }
     
@@ -77,6 +84,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base<T>'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type 'new (x: T, y: T) => T' is not assignable to type 'new (x: T) => T'.
+!!! error TS2430:       Signature 'new (x: T): T' has no corresponding signature in 'new (x: T, y: T) => T'
             a3: new (x: T, y: T) => T;  // error, too many required params
         }
     
@@ -139,6 +147,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new (x: T) => T' is not assignable to type 'new <T>() => T'.
+!!! error TS2430:       Signature 'new <T>(): T' has no corresponding signature in 'new (x: T) => T'
             a: new (x: T) => T; 
         }
     
@@ -173,6 +182,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10<T>' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type 'new (x: T, y: T) => T' is not assignable to type 'new <T>(x: T) => T'.
+!!! error TS2430:       Signature 'new <T>(x: T): T' has no corresponding signature in 'new (x: T, y: T) => T'
             a3: new (x: T, y: T) => T;  
         }
     
@@ -235,6 +245,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a' are incompatible.
 !!! error TS2430:     Type 'new <T>(x: T) => T' is not assignable to type 'new <T>() => T'.
+!!! error TS2430:       Signature 'new <T>(): T' has no corresponding signature in 'new <T>(x: T) => T'
             a: new <T>(x: T) => T; // error, not identical and contextual signature instatiation can't make inference from T to T
         }
     
@@ -269,6 +280,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
 !!! error TS2430: Interface 'I10' incorrectly extends interface 'Base2'.
 !!! error TS2430:   Types of property 'a3' are incompatible.
 !!! error TS2430:     Type 'new <T>(x: T, y: T) => T' is not assignable to type 'new <T>(x: T) => T'.
+!!! error TS2430:       Signature 'new <T>(x: T): T' has no corresponding signature in 'new <T>(x: T, y: T) => T'
             a3: new <T>(x: T, y: T) => T;  // error, too many required params
         }
     
diff --git a/tests/baselines/reference/symbolProperty24.errors.txt b/tests/baselines/reference/symbolProperty24.errors.txt
index 25cba184e25..58ff17544f9 100644
--- a/tests/baselines/reference/symbolProperty24.errors.txt
+++ b/tests/baselines/reference/symbolProperty24.errors.txt
@@ -1,7 +1,8 @@
 tests/cases/conformance/es6/Symbols/symbolProperty24.ts(5,7): error TS2420: Class 'C' incorrectly implements interface 'I'.
   Types of property '[Symbol.toPrimitive]' are incompatible.
     Type '() => string' is not assignable to type '() => boolean'.
-      Type 'string' is not assignable to type 'boolean'.
+      Signature '(): boolean' has no corresponding signature in '() => string'
+        Type 'string' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/conformance/es6/Symbols/symbolProperty24.ts (1 errors) ====
@@ -14,7 +15,8 @@ tests/cases/conformance/es6/Symbols/symbolProperty24.ts(5,7): error TS2420: Clas
 !!! error TS2420: Class 'C' incorrectly implements interface 'I'.
 !!! error TS2420:   Types of property '[Symbol.toPrimitive]' are incompatible.
 !!! error TS2420:     Type '() => string' is not assignable to type '() => boolean'.
-!!! error TS2420:       Type 'string' is not assignable to type 'boolean'.
+!!! error TS2420:       Signature '(): boolean' has no corresponding signature in '() => string'
+!!! error TS2420:         Type 'string' is not assignable to type 'boolean'.
         [Symbol.toPrimitive]() {
             return "";
         }
diff --git a/tests/baselines/reference/targetTypeVoidFunc.errors.txt b/tests/baselines/reference/targetTypeVoidFunc.errors.txt
index f9434c1d630..daa25885729 100644
--- a/tests/baselines/reference/targetTypeVoidFunc.errors.txt
+++ b/tests/baselines/reference/targetTypeVoidFunc.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/compiler/targetTypeVoidFunc.ts(2,12): error TS2322: Type '() => void' is not assignable to type 'new () => number'.
+  Signature 'new (): number' has no corresponding signature in '() => void'
 
 
 ==== tests/cases/compiler/targetTypeVoidFunc.ts (1 errors) ====
@@ -6,6 +7,7 @@ tests/cases/compiler/targetTypeVoidFunc.ts(2,12): error TS2322: Type '() => void
         return function () { return; }
                ~~~~~~~~
 !!! error TS2322: Type '() => void' is not assignable to type 'new () => number'.
+!!! error TS2322:   Signature 'new (): number' has no corresponding signature in '() => void'
     }; 
     
     var x = f1();
diff --git a/tests/baselines/reference/tupleTypes.errors.txt b/tests/baselines/reference/tupleTypes.errors.txt
index 8f418f98157..c1ef7f59454 100644
--- a/tests/baselines/reference/tupleTypes.errors.txt
+++ b/tests/baselines/reference/tupleTypes.errors.txt
@@ -10,13 +10,15 @@ tests/cases/compiler/tupleTypes.ts(41,1): error TS2322: Type 'undefined[]' is no
 tests/cases/compiler/tupleTypes.ts(47,1): error TS2322: Type '[number, string]' is not assignable to type 'number[]'.
   Types of property 'pop' are incompatible.
     Type '() => number | string' is not assignable to type '() => number'.
-      Type 'number | string' is not assignable to type 'number'.
-        Type 'string' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | string'
+        Type 'number | string' is not assignable to type 'number'.
+          Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/tupleTypes.ts(49,1): error TS2322: Type '[number, {}]' is not assignable to type 'number[]'.
   Types of property 'pop' are incompatible.
     Type '() => number | {}' is not assignable to type '() => number'.
-      Type 'number | {}' is not assignable to type 'number'.
-        Type '{}' is not assignable to type 'number'.
+      Signature '(): number' has no corresponding signature in '() => number | {}'
+        Type 'number | {}' is not assignable to type 'number'.
+          Type '{}' is not assignable to type 'number'.
 tests/cases/compiler/tupleTypes.ts(50,1): error TS2322: Type '[number, number]' is not assignable to type '[number, string]'.
   Types of property '1' are incompatible.
     Type 'number' is not assignable to type 'string'.
@@ -91,16 +93,18 @@ tests/cases/compiler/tupleTypes.ts(51,1): error TS2322: Type '[number, {}]' is n
 !!! error TS2322: Type '[number, string]' is not assignable to type 'number[]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | string' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'number | string' is not assignable to type 'number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => number | string'
+!!! error TS2322:         Type 'number | string' is not assignable to type 'number'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
     a = a2;
     a = a3;   // Error
     ~
 !!! error TS2322: Type '[number, {}]' is not assignable to type 'number[]'.
 !!! error TS2322:   Types of property 'pop' are incompatible.
 !!! error TS2322:     Type '() => number | {}' is not assignable to type '() => number'.
-!!! error TS2322:       Type 'number | {}' is not assignable to type 'number'.
-!!! error TS2322:         Type '{}' is not assignable to type 'number'.
+!!! error TS2322:       Signature '(): number' has no corresponding signature in '() => number | {}'
+!!! error TS2322:         Type 'number | {}' is not assignable to type 'number'.
+!!! error TS2322:           Type '{}' is not assignable to type 'number'.
     a1 = a2;  // Error
     ~~
 !!! error TS2322: Type '[number, number]' is not assignable to type '[number, string]'.
diff --git a/tests/baselines/reference/typeArgumentInferenceConstructSignatures.errors.txt b/tests/baselines/reference/typeArgumentInferenceConstructSignatures.errors.txt
index d058426b9c9..ecfb70a7776 100644
--- a/tests/baselines/reference/typeArgumentInferenceConstructSignatures.errors.txt
+++ b/tests/baselines/reference/typeArgumentInferenceConstructSignatures.errors.txt
@@ -1,14 +1,17 @@
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(25,35): error TS2345: Argument of type 'number' is not assignable to parameter of type 'string'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(51,19): error TS2304: Cannot find name 'Window'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(61,39): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(71,39): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(81,45): error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-  Types of parameters 'n' and 'b' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+    Types of parameters 'n' and 'b' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(106,15): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'string' is not a valid type argument because it is not a supertype of candidate 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstructSignatures.ts(118,9): error TS2304: Cannot find name 'Window'.
@@ -89,8 +92,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstruct
     new someGenerics4<string, number>('', (x: string) => ''); // Error
                                           ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     new someGenerics4<string, number>(null, null);
     
     // 2 parameter generic call with argument 2 of type parameter type and argument 1 of function type whose parameter is of type parameter type
@@ -103,8 +107,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstruct
     new someGenerics5<number, string>('', (x: string) => ''); // Error
                                           ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     new someGenerics5<string, number>(null, null);
     
     // Generic call with multiple arguments of function types that each have parameters of the same generic type
@@ -117,8 +122,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceConstruct
     new someGenerics6<number>((n: number) => n, (n: string) => n, (n: number) => n); // Error
                                                 ~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-!!! error TS2345:   Types of parameters 'n' and 'b' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+!!! error TS2345:     Types of parameters 'n' and 'b' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     new someGenerics6<number>((n: number) => n, (n: number) => n, (n: number) => n);
     
     // Generic call with multiple arguments of function types that each have parameters of different generic type
diff --git a/tests/baselines/reference/typeArgumentInferenceErrors.errors.txt b/tests/baselines/reference/typeArgumentInferenceErrors.errors.txt
index 9bd25dda4e6..dd9e29b7c31 100644
--- a/tests/baselines/reference/typeArgumentInferenceErrors.errors.txt
+++ b/tests/baselines/reference/typeArgumentInferenceErrors.errors.txt
@@ -1,13 +1,16 @@
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts(3,31): error TS2345: Argument of type 'number' is not assignable to parameter of type 'string'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts(7,35): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts(11,35): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts(15,41): error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-  Types of parameters 'n' and 'b' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+    Types of parameters 'n' and 'b' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts (4 errors) ====
@@ -22,22 +25,25 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceErrors.ts
     someGenerics4<string, number>('', (x: string) => ''); // Error
                                       ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     
     // 2 parameter generic call with argument 2 of type parameter type and argument 1 of function type whose parameter is of type parameter type
     function someGenerics5<U, T>(n: T, f: (x: U) => void) { }
     someGenerics5<number, string>('', (x: string) => ''); // Error
                                       ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     
     // Generic call with multiple arguments of function types that each have parameters of the same generic type
     function someGenerics6<A>(a: (a: A) => A, b: (b: A) => A, c: (c: A) => A) { }
     someGenerics6<number>((n: number) => n, (n: string) => n, (n: number) => n); // Error
                                             ~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-!!! error TS2345:   Types of parameters 'n' and 'b' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+!!! error TS2345:     Types of parameters 'n' and 'b' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeArgumentInferenceWithClassExpression2.errors.txt b/tests/baselines/reference/typeArgumentInferenceWithClassExpression2.errors.txt
index eb74ff0ade0..e949a0a2fd8 100644
--- a/tests/baselines/reference/typeArgumentInferenceWithClassExpression2.errors.txt
+++ b/tests/baselines/reference/typeArgumentInferenceWithClassExpression2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/conformance/es6/classExpressions/typeArgumentInferenceWithClassExpression2.ts(6,5): error TS2345: Argument of type 'typeof (Anonymous class)' is not assignable to parameter of type 'typeof (Anonymous class)'.
-  Type '(Anonymous class)' is not assignable to type 'foo<{}>.(Anonymous class)'.
-    Property 'prop' is missing in type '(Anonymous class)'.
+  Signature 'new (): foo<{}>.(Anonymous class)' has no corresponding signature in 'typeof (Anonymous class)'
+    Type '(Anonymous class)' is not assignable to type 'foo<{}>.(Anonymous class)'.
+      Property 'prop' is missing in type '(Anonymous class)'.
 
 
 ==== tests/cases/conformance/es6/classExpressions/typeArgumentInferenceWithClassExpression2.ts (1 errors) ====
@@ -12,5 +13,6 @@ tests/cases/conformance/es6/classExpressions/typeArgumentInferenceWithClassExpre
     foo(class { static prop = "hello" }).length;
         ~~~~~
 !!! error TS2345: Argument of type 'typeof (Anonymous class)' is not assignable to parameter of type 'typeof (Anonymous class)'.
-!!! error TS2345:   Type '(Anonymous class)' is not assignable to type 'foo<{}>.(Anonymous class)'.
-!!! error TS2345:     Property 'prop' is missing in type '(Anonymous class)'.
\ No newline at end of file
+!!! error TS2345:   Signature 'new (): foo<{}>.(Anonymous class)' has no corresponding signature in 'typeof (Anonymous class)'
+!!! error TS2345:     Type '(Anonymous class)' is not assignable to type 'foo<{}>.(Anonymous class)'.
+!!! error TS2345:       Property 'prop' is missing in type '(Anonymous class)'.
\ No newline at end of file
diff --git a/tests/baselines/reference/typeArgumentInferenceWithConstraints.errors.txt b/tests/baselines/reference/typeArgumentInferenceWithConstraints.errors.txt
index 0c1e8cc4e97..3f0390ec46a 100644
--- a/tests/baselines/reference/typeArgumentInferenceWithConstraints.errors.txt
+++ b/tests/baselines/reference/typeArgumentInferenceWithConstraints.errors.txt
@@ -4,15 +4,18 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConst
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(32,34): error TS2304: Cannot find name 'Window'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(34,15): error TS2304: Cannot find name 'Window'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(41,35): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(48,35): error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-  Types of parameters 'x' and 'x' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+    Types of parameters 'x' and 'x' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(49,15): error TS2344: Type 'string' does not satisfy the constraint 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(55,41): error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-  Types of parameters 'n' and 'b' are incompatible.
-    Type 'string' is not assignable to type 'number'.
+  Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+    Types of parameters 'n' and 'b' are incompatible.
+      Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(66,31): error TS2345: Argument of type '<A, B extends string, C>(a: (a: A) => A, b: (b: B) => B, c: (c: C) => C) => void' is not assignable to parameter of type 'string'.
 tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConstraints.ts(73,11): error TS2453: The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly.
   Type argument candidate 'string' is not a valid type argument because it is not a supertype of candidate 'number'.
@@ -80,8 +83,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConst
     someGenerics4<string, number>('', (x: string) => ''); // Error
                                       ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     someGenerics4<string, number>(null, null);
     
     // 2 parameter generic call with argument 2 of type parameter type and argument 1 of function type whose parameter is of type parameter type
@@ -91,8 +95,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConst
     someGenerics5<number, string>('', (x: string) => ''); // Error
                                       ~~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(x: string) => string' is not assignable to parameter of type '(x: number) => void'.
-!!! error TS2345:   Types of parameters 'x' and 'x' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(x: number): void' has no corresponding signature in '(x: string) => string'
+!!! error TS2345:     Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     someGenerics5<string, number>(null, null); // Error
                   ~~~~~~
 !!! error TS2344: Type 'string' does not satisfy the constraint 'number'.
@@ -104,8 +109,9 @@ tests/cases/conformance/expressions/functionCalls/typeArgumentInferenceWithConst
     someGenerics6<number>((n: number) => n, (n: string) => n, (n: number) => n); // Error
                                             ~~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '(n: string) => string' is not assignable to parameter of type '(b: number) => number'.
-!!! error TS2345:   Types of parameters 'n' and 'b' are incompatible.
-!!! error TS2345:     Type 'string' is not assignable to type 'number'.
+!!! error TS2345:   Signature '(b: number): number' has no corresponding signature in '(n: string) => string'
+!!! error TS2345:     Types of parameters 'n' and 'b' are incompatible.
+!!! error TS2345:       Type 'string' is not assignable to type 'number'.
     someGenerics6<number>((n: number) => n, (n: number) => n, (n: number) => n);
     
     // Generic call with multiple arguments of function types that each have parameters of different generic type
diff --git a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
index 92d9d21f0cc..fb17775bc31 100644
--- a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
+++ b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
@@ -14,14 +14,18 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(60,7):
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(65,7): error TS2339: Property 'propB' does not exist on type 'A'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(70,7): error TS2339: Property 'propB' does not exist on type 'A'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(75,46): error TS2345: Argument of type '(p1: any) => p1 is C' is not assignable to parameter of type '(p1: any) => p1 is B'.
-  Type predicate 'p1 is C' is not assignable to 'p1 is B'.
-    Type 'C' is not assignable to type 'B'.
+  Signature '(p1: any): p1 is B' has no corresponding signature in '(p1: any) => p1 is C'
+    Type predicate 'p1 is C' is not assignable to 'p1 is B'.
+      Type 'C' is not assignable to type 'B'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(79,1): error TS2322: Type '(p1: any, p2: any) => boolean' is not assignable to type '(p1: any, p2: any) => p1 is A'.
-  Signature '(p1: any, p2: any): boolean' must have a type predicate.
+  Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any) => boolean'
+    Signature '(p1: any, p2: any): boolean' must have a type predicate.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(85,1): error TS2322: Type '(p1: any, p2: any) => p2 is A' is not assignable to type '(p1: any, p2: any) => p1 is A'.
-  Type predicate 'p2 is A' is not assignable to 'p1 is A'.
-    Parameter 'p2' is not in the same position as parameter 'p1'.
+  Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any) => p2 is A'
+    Type predicate 'p2 is A' is not assignable to 'p1 is A'.
+      Parameter 'p2' is not in the same position as parameter 'p1'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(91,1): error TS2322: Type '(p1: any, p2: any, p3: any) => p1 is A' is not assignable to type '(p1: any, p2: any) => p1 is A'.
+  Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any, p3: any) => p1 is A'
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(96,9): error TS1228: A type predicate is only allowed in return type position for functions and methods.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(97,16): error TS1228: A type predicate is only allowed in return type position for functions and methods.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(98,20): error TS1228: A type predicate is only allowed in return type position for functions and methods.
@@ -147,15 +151,17 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(137,39
     acceptingDifferentSignatureTypeGuardFunction(isC);
                                                  ~~~
 !!! error TS2345: Argument of type '(p1: any) => p1 is C' is not assignable to parameter of type '(p1: any) => p1 is B'.
-!!! error TS2345:   Type predicate 'p1 is C' is not assignable to 'p1 is B'.
-!!! error TS2345:     Type 'C' is not assignable to type 'B'.
+!!! error TS2345:   Signature '(p1: any): p1 is B' has no corresponding signature in '(p1: any) => p1 is C'
+!!! error TS2345:     Type predicate 'p1 is C' is not assignable to 'p1 is B'.
+!!! error TS2345:       Type 'C' is not assignable to type 'B'.
     
     // Boolean not assignable to type guard
     var assign1: (p1, p2) => p1 is A;
     assign1 = function(p1, p2): boolean {
     ~~~~~~~
 !!! error TS2322: Type '(p1: any, p2: any) => boolean' is not assignable to type '(p1: any, p2: any) => p1 is A'.
-!!! error TS2322:   Signature '(p1: any, p2: any): boolean' must have a type predicate.
+!!! error TS2322:   Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any) => boolean'
+!!! error TS2322:     Signature '(p1: any, p2: any): boolean' must have a type predicate.
         return true;
     };
     
@@ -164,8 +170,9 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(137,39
     assign2 = function(p1, p2): p2 is A {
     ~~~~~~~
 !!! error TS2322: Type '(p1: any, p2: any) => p2 is A' is not assignable to type '(p1: any, p2: any) => p1 is A'.
-!!! error TS2322:   Type predicate 'p2 is A' is not assignable to 'p1 is A'.
-!!! error TS2322:     Parameter 'p2' is not in the same position as parameter 'p1'.
+!!! error TS2322:   Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any) => p2 is A'
+!!! error TS2322:     Type predicate 'p2 is A' is not assignable to 'p1 is A'.
+!!! error TS2322:       Parameter 'p2' is not in the same position as parameter 'p1'.
         return true;
     };
     
@@ -174,6 +181,7 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(137,39
     assign3 = function(p1, p2, p3): p1 is A {
     ~~~~~~~
 !!! error TS2322: Type '(p1: any, p2: any, p3: any) => p1 is A' is not assignable to type '(p1: any, p2: any) => p1 is A'.
+!!! error TS2322:   Signature '(p1: any, p2: any): p1 is A' has no corresponding signature in '(p1: any, p2: any, p3: any) => p1 is A'
         return true;
     };
     
diff --git a/tests/baselines/reference/typeName1.errors.txt b/tests/baselines/reference/typeName1.errors.txt
index 84c8be360bd..e77e7c58535 100644
--- a/tests/baselines/reference/typeName1.errors.txt
+++ b/tests/baselines/reference/typeName1.errors.txt
@@ -3,6 +3,7 @@ tests/cases/compiler/typeName1.ts(9,5): error TS2322: Type 'number' is not assig
 tests/cases/compiler/typeName1.ts(10,5): error TS2322: Type 'number' is not assignable to type '{ f(s: string): number; }'.
   Property 'f' is missing in type 'Number'.
 tests/cases/compiler/typeName1.ts(11,5): error TS2322: Type 'number' is not assignable to type '{ (s: string): number; (n: number): string; }'.
+  Signature '(s: string): number' has no corresponding signature in 'Number'
 tests/cases/compiler/typeName1.ts(12,5): error TS2322: Type 'number' is not assignable to type '{ x: any; y: any; z: number; f(n: number): string; f(s: string): number; }'.
   Property 'x' is missing in type 'Number'.
 tests/cases/compiler/typeName1.ts(13,5): error TS2322: Type 'number' is not assignable to type '{ (s: string): number; (n: number): string; x: any; y: any; z: number; f(n: number): string; f(s: string): number; }'.
@@ -10,6 +11,7 @@ tests/cases/compiler/typeName1.ts(13,5): error TS2322: Type 'number' is not assi
 tests/cases/compiler/typeName1.ts(14,5): error TS2322: Type 'number' is not assignable to type '{ z: number; f: { (n: number): string; (s: string): number; }; }'.
   Property 'z' is missing in type 'Number'.
 tests/cases/compiler/typeName1.ts(15,5): error TS2322: Type 'number' is not assignable to type '(s: string) => boolean'.
+  Signature '(s: string): boolean' has no corresponding signature in 'Number'
 tests/cases/compiler/typeName1.ts(16,5): error TS2322: Type 'number' is not assignable to type '{ (): boolean; [s: string]: { x: any; y: any; }; [n: number]: { x: any; y: any; }; z: I; }'.
   Property 'z' is missing in type 'Number'.
 tests/cases/compiler/typeName1.ts(16,10): error TS2411: Property 'z' of type 'I' is not assignable to string index type '{ x: any; y: any; }'.
@@ -49,6 +51,7 @@ tests/cases/compiler/typeName1.ts(23,5): error TS2322: Type 'typeof C' is not as
     var x3:{ (s:string):number;(n:number):string; }=3;
         ~~
 !!! error TS2322: Type 'number' is not assignable to type '{ (s: string): number; (n: number): string; }'.
+!!! error TS2322:   Signature '(s: string): number' has no corresponding signature in 'Number'
     var x4:{ x;y;z:number;f(n:number):string;f(s:string):number; }=3;
         ~~
 !!! error TS2322: Type 'number' is not assignable to type '{ x: any; y: any; z: number; f(n: number): string; f(s: string): number; }'.
@@ -64,6 +67,7 @@ tests/cases/compiler/typeName1.ts(23,5): error TS2322: Type 'typeof C' is not as
     var x7:(s:string)=>boolean=3;
         ~~
 !!! error TS2322: Type 'number' is not assignable to type '(s: string) => boolean'.
+!!! error TS2322:   Signature '(s: string): boolean' has no corresponding signature in 'Number'
     var x8:{ z:I;[s:string]:{ x; y; };[n:number]:{x; y;};():boolean; }=3;
         ~~
 !!! error TS2322: Type 'number' is not assignable to type '{ (): boolean; [s: string]: { x: any; y: any; }; [n: number]: { x: any; y: any; }; z: I; }'.
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence.errors.txt
index f47266f2850..789820116ba 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/typeParameterArgumentEquivalence.ts(4,5): error TS2322: Type '(item: T) => boolean' is not assignable to type '(item: number) => boolean'.
-  Types of parameters 'item' and 'item' are incompatible.
-    Type 'T' is not assignable to type 'number'.
+  Signature '(item: number): boolean' has no corresponding signature in '(item: T) => boolean'
+    Types of parameters 'item' and 'item' are incompatible.
+      Type 'T' is not assignable to type 'number'.
 tests/cases/compiler/typeParameterArgumentEquivalence.ts(5,5): error TS2322: Type '(item: number) => boolean' is not assignable to type '(item: T) => boolean'.
-  Types of parameters 'item' and 'item' are incompatible.
-    Type 'number' is not assignable to type 'T'.
+  Signature '(item: T): boolean' has no corresponding signature in '(item: number) => boolean'
+    Types of parameters 'item' and 'item' are incompatible.
+      Type 'number' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/typeParameterArgumentEquivalence.ts (2 errors) ====
@@ -13,12 +15,14 @@ tests/cases/compiler/typeParameterArgumentEquivalence.ts(5,5): error TS2322: Typ
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '(item: T) => boolean' is not assignable to type '(item: number) => boolean'.
-!!! error TS2322:   Types of parameters 'item' and 'item' are incompatible.
-!!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! error TS2322:   Signature '(item: number): boolean' has no corresponding signature in '(item: T) => boolean'
+!!! error TS2322:     Types of parameters 'item' and 'item' are incompatible.
+!!! error TS2322:       Type 'T' is not assignable to type 'number'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '(item: number) => boolean' is not assignable to type '(item: T) => boolean'.
-!!! error TS2322:   Types of parameters 'item' and 'item' are incompatible.
-!!! error TS2322:     Type 'number' is not assignable to type 'T'.
+!!! error TS2322:   Signature '(item: T): boolean' has no corresponding signature in '(item: number) => boolean'
+!!! error TS2322:     Types of parameters 'item' and 'item' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'T'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence2.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence2.errors.txt
index 2aa8d77ba6d..a50fd533ae6 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence2.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence2.errors.txt
@@ -1,9 +1,11 @@
 tests/cases/compiler/typeParameterArgumentEquivalence2.ts(4,5): error TS2322: Type '(item: T) => boolean' is not assignable to type '(item: U) => boolean'.
-  Types of parameters 'item' and 'item' are incompatible.
-    Type 'T' is not assignable to type 'U'.
+  Signature '(item: U): boolean' has no corresponding signature in '(item: T) => boolean'
+    Types of parameters 'item' and 'item' are incompatible.
+      Type 'T' is not assignable to type 'U'.
 tests/cases/compiler/typeParameterArgumentEquivalence2.ts(5,5): error TS2322: Type '(item: U) => boolean' is not assignable to type '(item: T) => boolean'.
-  Types of parameters 'item' and 'item' are incompatible.
-    Type 'U' is not assignable to type 'T'.
+  Signature '(item: T): boolean' has no corresponding signature in '(item: U) => boolean'
+    Types of parameters 'item' and 'item' are incompatible.
+      Type 'U' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/typeParameterArgumentEquivalence2.ts (2 errors) ====
@@ -13,12 +15,14 @@ tests/cases/compiler/typeParameterArgumentEquivalence2.ts(5,5): error TS2322: Ty
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '(item: T) => boolean' is not assignable to type '(item: U) => boolean'.
-!!! error TS2322:   Types of parameters 'item' and 'item' are incompatible.
-!!! error TS2322:     Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Signature '(item: U): boolean' has no corresponding signature in '(item: T) => boolean'
+!!! error TS2322:     Types of parameters 'item' and 'item' are incompatible.
+!!! error TS2322:       Type 'T' is not assignable to type 'U'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '(item: U) => boolean' is not assignable to type '(item: T) => boolean'.
-!!! error TS2322:   Types of parameters 'item' and 'item' are incompatible.
-!!! error TS2322:     Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Signature '(item: T): boolean' has no corresponding signature in '(item: U) => boolean'
+!!! error TS2322:     Types of parameters 'item' and 'item' are incompatible.
+!!! error TS2322:       Type 'U' is not assignable to type 'T'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence3.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence3.errors.txt
index 1f126d7c00d..50e33c7afa4 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence3.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence3.errors.txt
@@ -1,7 +1,9 @@
 tests/cases/compiler/typeParameterArgumentEquivalence3.ts(4,5): error TS2322: Type '(item: any) => boolean' is not assignable to type '(item: any) => T'.
-  Type 'boolean' is not assignable to type 'T'.
+  Signature '(item: any): T' has no corresponding signature in '(item: any) => boolean'
+    Type 'boolean' is not assignable to type 'T'.
 tests/cases/compiler/typeParameterArgumentEquivalence3.ts(5,5): error TS2322: Type '(item: any) => T' is not assignable to type '(item: any) => boolean'.
-  Type 'T' is not assignable to type 'boolean'.
+  Signature '(item: any): boolean' has no corresponding signature in '(item: any) => T'
+    Type 'T' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/typeParameterArgumentEquivalence3.ts (2 errors) ====
@@ -11,10 +13,12 @@ tests/cases/compiler/typeParameterArgumentEquivalence3.ts(5,5): error TS2322: Ty
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '(item: any) => boolean' is not assignable to type '(item: any) => T'.
-!!! error TS2322:   Type 'boolean' is not assignable to type 'T'.
+!!! error TS2322:   Signature '(item: any): T' has no corresponding signature in '(item: any) => boolean'
+!!! error TS2322:     Type 'boolean' is not assignable to type 'T'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '(item: any) => T' is not assignable to type '(item: any) => boolean'.
-!!! error TS2322:   Type 'T' is not assignable to type 'boolean'.
+!!! error TS2322:   Signature '(item: any): boolean' has no corresponding signature in '(item: any) => T'
+!!! error TS2322:     Type 'T' is not assignable to type 'boolean'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence4.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence4.errors.txt
index c7b19e8725c..68ab8dc28df 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence4.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence4.errors.txt
@@ -1,7 +1,9 @@
 tests/cases/compiler/typeParameterArgumentEquivalence4.ts(4,5): error TS2322: Type '(item: any) => T' is not assignable to type '(item: any) => U'.
-  Type 'T' is not assignable to type 'U'.
+  Signature '(item: any): U' has no corresponding signature in '(item: any) => T'
+    Type 'T' is not assignable to type 'U'.
 tests/cases/compiler/typeParameterArgumentEquivalence4.ts(5,5): error TS2322: Type '(item: any) => U' is not assignable to type '(item: any) => T'.
-  Type 'U' is not assignable to type 'T'.
+  Signature '(item: any): T' has no corresponding signature in '(item: any) => U'
+    Type 'U' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/typeParameterArgumentEquivalence4.ts (2 errors) ====
@@ -11,10 +13,12 @@ tests/cases/compiler/typeParameterArgumentEquivalence4.ts(5,5): error TS2322: Ty
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '(item: any) => T' is not assignable to type '(item: any) => U'.
-!!! error TS2322:   Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Signature '(item: any): U' has no corresponding signature in '(item: any) => T'
+!!! error TS2322:     Type 'T' is not assignable to type 'U'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '(item: any) => U' is not assignable to type '(item: any) => T'.
-!!! error TS2322:   Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Signature '(item: any): T' has no corresponding signature in '(item: any) => U'
+!!! error TS2322:     Type 'U' is not assignable to type 'T'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
index 82290733a9e..8e1ac388a82 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
@@ -1,9 +1,13 @@
 tests/cases/compiler/typeParameterArgumentEquivalence5.ts(4,5): error TS2322: Type '() => (item: any) => T' is not assignable to type '() => (item: any) => U'.
-  Type '(item: any) => T' is not assignable to type '(item: any) => U'.
-    Type 'T' is not assignable to type 'U'.
+  Signature '(): (item: any) => U' has no corresponding signature in '() => (item: any) => T'
+    Type '(item: any) => T' is not assignable to type '(item: any) => U'.
+      Signature '(item: any): U' has no corresponding signature in '(item: any) => T'
+        Type 'T' is not assignable to type 'U'.
 tests/cases/compiler/typeParameterArgumentEquivalence5.ts(5,5): error TS2322: Type '() => (item: any) => U' is not assignable to type '() => (item: any) => T'.
-  Type '(item: any) => U' is not assignable to type '(item: any) => T'.
-    Type 'U' is not assignable to type 'T'.
+  Signature '(): (item: any) => T' has no corresponding signature in '() => (item: any) => U'
+    Type '(item: any) => U' is not assignable to type '(item: any) => T'.
+      Signature '(item: any): T' has no corresponding signature in '(item: any) => U'
+        Type 'U' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/typeParameterArgumentEquivalence5.ts (2 errors) ====
@@ -13,12 +17,16 @@ tests/cases/compiler/typeParameterArgumentEquivalence5.ts(5,5): error TS2322: Ty
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '() => (item: any) => T' is not assignable to type '() => (item: any) => U'.
-!!! error TS2322:   Type '(item: any) => T' is not assignable to type '(item: any) => U'.
-!!! error TS2322:     Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Signature '(): (item: any) => U' has no corresponding signature in '() => (item: any) => T'
+!!! error TS2322:     Type '(item: any) => T' is not assignable to type '(item: any) => U'.
+!!! error TS2322:       Signature '(item: any): U' has no corresponding signature in '(item: any) => T'
+!!! error TS2322:         Type 'T' is not assignable to type 'U'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '() => (item: any) => U' is not assignable to type '() => (item: any) => T'.
-!!! error TS2322:   Type '(item: any) => U' is not assignable to type '(item: any) => T'.
-!!! error TS2322:     Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Signature '(): (item: any) => T' has no corresponding signature in '() => (item: any) => U'
+!!! error TS2322:     Type '(item: any) => U' is not assignable to type '(item: any) => T'.
+!!! error TS2322:       Signature '(item: any): T' has no corresponding signature in '(item: any) => U'
+!!! error TS2322:         Type 'U' is not assignable to type 'T'.
     }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments2.errors.txt b/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments2.errors.txt
index 5a6047222ee..8d926a14378 100644
--- a/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments2.errors.txt
+++ b/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments2.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments2.ts(7,25): error TS2345: Argument of type '(x: A) => A' is not assignable to parameter of type '(x: A) => B'.
-  Type 'A' is not assignable to type 'B'.
-    Property 'b' is missing in type 'A'.
+  Signature '(x: A): B' has no corresponding signature in '(x: A) => A'
+    Type 'A' is not assignable to type 'B'.
+      Property 'b' is missing in type 'A'.
 
 
 ==== tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments2.ts (1 errors) ====
@@ -13,5 +14,6 @@ tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments2.ts(7,25):
     var d = f(a, b, x => x, x => x); // A => A not assignable to A => B
                             ~~~~~~
 !!! error TS2345: Argument of type '(x: A) => A' is not assignable to parameter of type '(x: A) => B'.
-!!! error TS2345:   Type 'A' is not assignable to type 'B'.
-!!! error TS2345:     Property 'b' is missing in type 'A'.
\ No newline at end of file
+!!! error TS2345:   Signature '(x: A): B' has no corresponding signature in '(x: A) => A'
+!!! error TS2345:     Type 'A' is not assignable to type 'B'.
+!!! error TS2345:       Property 'b' is missing in type 'A'.
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments3.errors.txt b/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments3.errors.txt
index cd0801f7ba9..c93aa87f44b 100644
--- a/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments3.errors.txt
+++ b/tests/baselines/reference/typeParameterFixingWithContextSensitiveArguments3.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments3.ts(7,29): error TS2345: Argument of type '(t2: A) => A' is not assignable to parameter of type '(t2: A) => B'.
-  Type 'A' is not assignable to type 'B'.
-    Property 'b' is missing in type 'A'.
+  Signature '(t2: A): B' has no corresponding signature in '(t2: A) => A'
+    Type 'A' is not assignable to type 'B'.
+      Property 'b' is missing in type 'A'.
 
 
 ==== tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments3.ts (1 errors) ====
@@ -13,5 +14,6 @@ tests/cases/compiler/typeParameterFixingWithContextSensitiveArguments3.ts(7,29):
     var d = f(a, b, u2 => u2.b, t2 => t2);
                                 ~~~~~~~~
 !!! error TS2345: Argument of type '(t2: A) => A' is not assignable to parameter of type '(t2: A) => B'.
-!!! error TS2345:   Type 'A' is not assignable to type 'B'.
-!!! error TS2345:     Property 'b' is missing in type 'A'.
\ No newline at end of file
+!!! error TS2345:   Signature '(t2: A): B' has no corresponding signature in '(t2: A) => A'
+!!! error TS2345:     Type 'A' is not assignable to type 'B'.
+!!! error TS2345:       Property 'b' is missing in type 'A'.
\ No newline at end of file
diff --git a/tests/baselines/reference/typesWithPrivateConstructor.errors.txt b/tests/baselines/reference/typesWithPrivateConstructor.errors.txt
index 2440e51cd39..d2a4e766ebc 100644
--- a/tests/baselines/reference/typesWithPrivateConstructor.errors.txt
+++ b/tests/baselines/reference/typesWithPrivateConstructor.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(4,5): error TS1089: 'private' modifier cannot appear on a constructor declaration.
 tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(8,5): error TS2322: Type 'Function' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in 'Function'
 tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(11,5): error TS1089: 'private' modifier cannot appear on a constructor declaration.
 tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(12,5): error TS1089: 'private' modifier cannot appear on a constructor declaration.
 tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(15,10): error TS2346: Supplied parameters do not match any signature of call target.
@@ -18,6 +19,7 @@ tests/cases/conformance/types/members/typesWithPrivateConstructor.ts(15,10): err
     var r: () => void = c.constructor;
         ~
 !!! error TS2322: Type 'Function' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Function'
     
     class C2 {
         private constructor(x: number);
diff --git a/tests/baselines/reference/typesWithPublicConstructor.errors.txt b/tests/baselines/reference/typesWithPublicConstructor.errors.txt
index a3d66c3520a..6aa06afcdab 100644
--- a/tests/baselines/reference/typesWithPublicConstructor.errors.txt
+++ b/tests/baselines/reference/typesWithPublicConstructor.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/members/typesWithPublicConstructor.ts(8,5): error TS2322: Type 'Function' is not assignable to type '() => void'.
+  Signature '(): void' has no corresponding signature in 'Function'
 tests/cases/conformance/types/members/typesWithPublicConstructor.ts(15,10): error TS2346: Supplied parameters do not match any signature of call target.
 
 
@@ -13,6 +14,7 @@ tests/cases/conformance/types/members/typesWithPublicConstructor.ts(15,10): erro
     var r: () => void = c.constructor;
         ~
 !!! error TS2322: Type 'Function' is not assignable to type '() => void'.
+!!! error TS2322:   Signature '(): void' has no corresponding signature in 'Function'
     
     class C2 {
         public constructor(x: number);
diff --git a/tests/baselines/reference/undeclaredModuleError.errors.txt b/tests/baselines/reference/undeclaredModuleError.errors.txt
index 74e36318595..3c1f930856c 100644
--- a/tests/baselines/reference/undeclaredModuleError.errors.txt
+++ b/tests/baselines/reference/undeclaredModuleError.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/compiler/undeclaredModuleError.ts(1,21): error TS2307: Cannot find module 'fs'.
 tests/cases/compiler/undeclaredModuleError.ts(8,29): error TS2345: Argument of type '() => void' is not assignable to parameter of type '(stat: any, name: string) => boolean'.
-  Type 'void' is not assignable to type 'boolean'.
+  Signature '(stat: any, name: string): boolean' has no corresponding signature in '() => void'
+    Type 'void' is not assignable to type 'boolean'.
 tests/cases/compiler/undeclaredModuleError.ts(11,41): error TS2304: Cannot find name 'IDoNotExist'.
 
 
@@ -19,7 +20,8 @@ tests/cases/compiler/undeclaredModuleError.ts(11,41): error TS2304: Cannot find
             } , (error: Error, files: {}[]) => {
     ~~~~~~~~~
 !!! error TS2345: Argument of type '() => void' is not assignable to parameter of type '(stat: any, name: string) => boolean'.
-!!! error TS2345:   Type 'void' is not assignable to type 'boolean'.
+!!! error TS2345:   Signature '(stat: any, name: string): boolean' has no corresponding signature in '() => void'
+!!! error TS2345:     Type 'void' is not assignable to type 'boolean'.
                     files.forEach((file) => {
                         var fullPath = join(IDoNotExist);
                                             ~~~~~~~~~~~