diff --git a/tests/baselines/reference/bigintWithLib.errors.txt b/tests/baselines/reference/bigintWithLib.errors.txt
index 33a860b59b4..006847c4824 100644
--- a/tests/baselines/reference/bigintWithLib.errors.txt
+++ b/tests/baselines/reference/bigintWithLib.errors.txt
@@ -6,7 +6,7 @@ tests/cases/compiler/bigintWithLib.ts(19,33): error TS2769: No overload matches
     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
         Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint> | IteratorReturnResult<any>'.
+          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
             Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
               Type 'number' is not assignable to type 'bigint'.
   Overload 3 of 3, '(buffer: ArrayBufferLike, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
@@ -56,7 +56,7 @@ tests/cases/compiler/bigintWithLib.ts(46,26): error TS2345: Argument of type 'nu
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
 !!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
 !!! error TS2769:         Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-!!! error TS2769:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint> | IteratorReturnResult<any>'.
+!!! error TS2769:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
 !!! error TS2769:             Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
 !!! error TS2769:               Type 'number' is not assignable to type 'bigint'.
 !!! error TS2769:   Overload 3 of 3, '(buffer: ArrayBufferLike, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
diff --git a/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt b/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt
index 34bd2189964..98afca17324 100644
--- a/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt
+++ b/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/conformance/jsx/file.tsx(24,28): error TS2551: Property 'NAme' does not exist on type 'IUser'. Did you mean 'Name'?
-tests/cases/conformance/jsx/file.tsx(36,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+tests/cases/conformance/jsx/file.tsx(36,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'boolean | any[] | ReactChild'.
   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
-tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'boolean | any[] | ReactChild'.
   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 
 
@@ -50,7 +50,7 @@ tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) =
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 ) }
     ~~~~~~~~~~~~~
-!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'boolean | any[] | ReactChild'.
 !!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 !!! related TS6212 tests/cases/conformance/jsx/file.tsx:36:15: Did you mean to call this expression?
                 { user => (
@@ -59,7 +59,7 @@ tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) =
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 ) }
     ~~~~~~~~~~~~~
-!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'boolean | any[] | ReactChild'.
 !!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 !!! related TS6212 tests/cases/conformance/jsx/file.tsx:39:15: Did you mean to call this expression?
             </FetchUser>
diff --git a/tests/baselines/reference/enumLiteralTypes3.errors.txt b/tests/baselines/reference/enumLiteralTypes3.errors.txt
index e17f3280150..1ba3e3fd798 100644
--- a/tests/baselines/reference/enumLiteralTypes3.errors.txt
+++ b/tests/baselines/reference/enumLiteralTypes3.errors.txt
@@ -4,7 +4,7 @@ tests/cases/conformance/types/literal/enumLiteralTypes3.ts(11,5): error TS2322:
   Type 'Choice.Unknown' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/enumLiteralTypes3.ts(12,5): error TS2322: Type 'Choice' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/enumLiteralTypes3.ts(18,5): error TS2322: Type 'UnknownYesNo' is not assignable to type 'YesNo'.
-  Type 'Choice.Unknown' is not assignable to type 'Choice.Yes | Choice.No'.
+  Type 'Choice.Unknown' is not assignable to type 'YesNo'.
 tests/cases/conformance/types/literal/enumLiteralTypes3.ts(19,5): error TS2322: Type 'Choice' is not assignable to type 'YesNo'.
 tests/cases/conformance/types/literal/enumLiteralTypes3.ts(37,5): error TS2322: Type 'Choice.Unknown' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/enumLiteralTypes3.ts(39,5): error TS2322: Type 'Choice.No' is not assignable to type 'Choice.Yes'.
@@ -46,7 +46,7 @@ tests/cases/conformance/types/literal/enumLiteralTypes3.ts(96,14): error TS2678:
         b = c;
         ~
 !!! error TS2322: Type 'UnknownYesNo' is not assignable to type 'YesNo'.
-!!! error TS2322:   Type 'Choice.Unknown' is not assignable to type 'Choice.Yes | Choice.No'.
+!!! error TS2322:   Type 'Choice.Unknown' is not assignable to type 'YesNo'.
         b = d;
         ~
 !!! error TS2322: Type 'Choice' is not assignable to type 'YesNo'.
diff --git a/tests/baselines/reference/errorMessageOnIntersectionsWithDiscriminants01.errors.txt b/tests/baselines/reference/errorMessageOnIntersectionsWithDiscriminants01.errors.txt
index 8510e1f9d18..1acdc1587f4 100644
--- a/tests/baselines/reference/errorMessageOnIntersectionsWithDiscriminants01.errors.txt
+++ b/tests/baselines/reference/errorMessageOnIntersectionsWithDiscriminants01.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/errorMessageOnIntersectionsWithDiscriminants01.ts(8,1): error TS2322: Type 'A' is not assignable to type 'B'.
-  Type '{ test: true; } & { foo: 1; }' is not assignable to type '({ test: true; } & { bar: 1; }) | ({ test: false; } & { bar: 1; })'.
+  Type '{ test: true; } & { foo: 1; }' is not assignable to type 'B'.
     Type '{ test: true; } & { foo: 1; }' is not assignable to type '{ test: true; } & { bar: 1; }'.
       Property 'bar' is missing in type '{ test: true; } & { foo: 1; }' but required in type '{ bar: 1; }'.
 
@@ -15,7 +15,7 @@ tests/cases/compiler/errorMessageOnIntersectionsWithDiscriminants01.ts(8,1): err
     b = a;
     ~
 !!! error TS2322: Type 'A' is not assignable to type 'B'.
-!!! error TS2322:   Type '{ test: true; } & { foo: 1; }' is not assignable to type '({ test: true; } & { bar: 1; }) | ({ test: false; } & { bar: 1; })'.
+!!! error TS2322:   Type '{ test: true; } & { foo: 1; }' is not assignable to type 'B'.
 !!! error TS2322:     Type '{ test: true; } & { foo: 1; }' is not assignable to type '{ test: true; } & { bar: 1; }'.
 !!! error TS2322:       Property 'bar' is missing in type '{ test: true; } & { foo: 1; }' but required in type '{ bar: 1; }'.
 !!! related TS2728 tests/cases/compiler/errorMessageOnIntersectionsWithDiscriminants01.ts:3:28: 'bar' is declared here.
diff --git a/tests/baselines/reference/errorsOnUnionsOfOverlappingObjects01.errors.txt b/tests/baselines/reference/errorsOnUnionsOfOverlappingObjects01.errors.txt
index cf54512f973..57d30acaba9 100644
--- a/tests/baselines/reference/errorsOnUnionsOfOverlappingObjects01.errors.txt
+++ b/tests/baselines/reference/errorsOnUnionsOfOverlappingObjects01.errors.txt
@@ -10,7 +10,7 @@ tests/cases/compiler/errorsOnUnionsOfOverlappingObjects01.ts(42,10): error TS234
 tests/cases/compiler/errorsOnUnionsOfOverlappingObjects01.ts(43,10): error TS2345: Argument of type '{ man: string; bear: string; }' is not assignable to parameter of type 'ExoticAnimal'.
   Property 'pig' is missing in type '{ man: string; bear: string; }' but required in type 'ManBearPig'.
 tests/cases/compiler/errorsOnUnionsOfOverlappingObjects01.ts(46,26): error TS2345: Argument of type '{ man: string; beer: string; }' is not assignable to parameter of type 'ExoticAnimal'.
-  Object literal may only specify known properties, and 'beer' does not exist in type 'CatDog | ManBearPig | Platypus'.
+  Object literal may only specify known properties, and 'beer' does not exist in type 'ExoticAnimal'.
 tests/cases/compiler/errorsOnUnionsOfOverlappingObjects01.ts(47,10): error TS2345: Argument of type '{ man: string; beer: string; }' is not assignable to parameter of type 'ExoticAnimal'.
   Type '{ man: string; beer: string; }' is missing the following properties from type 'ManBearPig': bear, pig
 
@@ -82,7 +82,7 @@ tests/cases/compiler/errorsOnUnionsOfOverlappingObjects01.ts(47,10): error TS234
     addToZoo({ man: "Manny", beer: "Coffee" });
                              ~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ man: string; beer: string; }' is not assignable to parameter of type 'ExoticAnimal'.
-!!! error TS2345:   Object literal may only specify known properties, and 'beer' does not exist in type 'CatDog | ManBearPig | Platypus'.
+!!! error TS2345:   Object literal may only specify known properties, and 'beer' does not exist in type 'ExoticAnimal'.
     addToZoo(manBeer);
              ~~~~~~~
 !!! error TS2345: Argument of type '{ man: string; beer: string; }' is not assignable to parameter of type 'ExoticAnimal'.
diff --git a/tests/baselines/reference/excessPropertyCheckWithUnions.errors.txt b/tests/baselines/reference/excessPropertyCheckWithUnions.errors.txt
index 1b0ec63fbd0..8c34a0f5d69 100644
--- a/tests/baselines/reference/excessPropertyCheckWithUnions.errors.txt
+++ b/tests/baselines/reference/excessPropertyCheckWithUnions.errors.txt
@@ -5,9 +5,9 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(11,21): error TS2322: Type
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(12,1): error TS2322: Type '{ tag: "D"; }' is not assignable to type 'ADT'.
   Property 'd20' is missing in type '{ tag: "D"; }' but required in type '{ tag: "D"; d20: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20; }'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(33,28): error TS2322: Type '{ tag: "A"; x: string; extra: number; }' is not assignable to type 'Ambiguous'.
-  Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; } | { tag: "B"; z: boolean; } | { tag: "C"; }'.
+  Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(34,26): error TS2322: Type '{ tag: "A"; y: number; extra: number; }' is not assignable to type 'Ambiguous'.
-  Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; } | { tag: "B"; z: boolean; } | { tag: "C"; }'.
+  Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(39,1): error TS2322: Type '{ tag: "A"; }' is not assignable to type 'Ambiguous'.
   Type '{ tag: "A"; }' is not assignable to type '{ tag: "C"; }'.
     Types of property 'tag' are incompatible.
@@ -23,7 +23,7 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(50,35): error TS2322: Type
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(66,9): error TS2322: Type '{ kind: "A"; n: { a: string; b: string; }; }' is not assignable to type 'AB'.
   Types of property 'n' are incompatible.
     Type '{ a: string; b: string; }' is not assignable to type 'AN'.
-      Object literal may only specify known properties, and 'b' does not exist in type '{ a: string; } | { c: string; }'.
+      Object literal may only specify known properties, and 'b' does not exist in type 'AN'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(87,5): error TS2322: Type '{ tag: "button"; type: "submit"; href: string; }' is not assignable to type 'Union'.
   Object literal may only specify known properties, and 'href' does not exist in type 'Button'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(108,5): error TS2322: Type 'string' is not assignable to type 'IValue'.
@@ -77,11 +77,11 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(114,63): error TS2322: Typ
     amb = { tag: "A", x: "hi", extra: 12 }
                                ~~~~~~~~~
 !!! error TS2322: Type '{ tag: "A"; x: string; extra: number; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; } | { tag: "B"; z: boolean; } | { tag: "C"; }'.
+!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
     amb = { tag: "A", y: 12, extra: 12 }
                              ~~~~~~~~~
 !!! error TS2322: Type '{ tag: "A"; y: number; extra: number; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; } | { tag: "B"; z: boolean; } | { tag: "C"; }'.
+!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
     
     // assignability errors still work.
     // But note that the error for `z: true` is the fallback one of reporting on
@@ -134,7 +134,7 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(114,63): error TS2322: Typ
 !!! error TS2322: Type '{ kind: "A"; n: { a: string; b: string; }; }' is not assignable to type 'AB'.
 !!! error TS2322:   Types of property 'n' are incompatible.
 !!! error TS2322:     Type '{ a: string; b: string; }' is not assignable to type 'AN'.
-!!! error TS2322:       Object literal may only specify known properties, and 'b' does not exist in type '{ a: string; } | { c: string; }'.
+!!! error TS2322:       Object literal may only specify known properties, and 'b' does not exist in type 'AN'.
         }
     }
     const abac: AB = {
diff --git a/tests/baselines/reference/excessPropertyErrorForFunctionTypes.errors.txt b/tests/baselines/reference/excessPropertyErrorForFunctionTypes.errors.txt
index 030ca516221..961308059ba 100644
--- a/tests/baselines/reference/excessPropertyErrorForFunctionTypes.errors.txt
+++ b/tests/baselines/reference/excessPropertyErrorForFunctionTypes.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/excessPropertyErrorForFunctionTypes.ts(4,44): error TS2322: Type '{ a: number; c: number; d: number; }' is not assignable to type 'DoesntWork'.
-  Object literal may only specify known properties, and 'd' does not exist in type '{ a: number; c: number; } | FunctionType'.
+  Object literal may only specify known properties, and 'd' does not exist in type 'DoesntWork'.
 
 
 ==== tests/cases/compiler/excessPropertyErrorForFunctionTypes.ts (1 errors) ====
@@ -9,4 +9,4 @@ tests/cases/compiler/excessPropertyErrorForFunctionTypes.ts(4,44): error TS2322:
     let doesntWork: DoesntWork = { a: 1, c: 2, d: 3 }
                                                ~~~~
 !!! error TS2322: Type '{ a: number; c: number; d: number; }' is not assignable to type 'DoesntWork'.
-!!! error TS2322:   Object literal may only specify known properties, and 'd' does not exist in type '{ a: number; c: number; } | FunctionType'.
\ No newline at end of file
+!!! error TS2322:   Object literal may only specify known properties, and 'd' does not exist in type 'DoesntWork'.
\ No newline at end of file
diff --git a/tests/baselines/reference/for-of39.errors.txt b/tests/baselines/reference/for-of39.errors.txt
index 31e1fba627d..3ecdc46bcfc 100644
--- a/tests/baselines/reference/for-of39.errors.txt
+++ b/tests/baselines/reference/for-of39.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,11): error TS2769: No
     Argument of type '([string, number] | [string, true])[]' is not assignable to parameter of type 'Iterable<readonly [string, boolean]>'.
       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
         Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-          Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<readonly [string, boolean]>'.
+          Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
             Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
               Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
                 Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
@@ -21,7 +21,7 @@ tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,11): error TS2769: No
 !!! error TS2769:     Argument of type '([string, number] | [string, true])[]' is not assignable to parameter of type 'Iterable<readonly [string, boolean]>'.
 !!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
 !!! error TS2769:         Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<readonly [string, boolean]>'.
+!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
 !!! error TS2769:             Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
 !!! error TS2769:               Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
 !!! error TS2769:                 Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
diff --git a/tests/baselines/reference/generatorTypeCheck25.errors.txt b/tests/baselines/reference/generatorTypeCheck25.errors.txt
index 7d5361d128e..e37f1304963 100644
--- a/tests/baselines/reference/generatorTypeCheck25.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck25.errors.txt
@@ -2,7 +2,7 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error
   Call signature return types 'Generator<Bar | Baz, void, undefined>' and 'Iterable<Foo>' are incompatible.
     The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
       Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
-        Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo> | IteratorReturnResult<any>'.
+        Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
           Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
             Type 'Bar | Baz' is not assignable to type 'Foo'.
               Property 'x' is missing in type 'Baz' but required in type 'Foo'.
@@ -18,7 +18,7 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error
 !!! error TS2322:   Call signature return types 'Generator<Bar | Baz, void, undefined>' and 'Iterable<Foo>' are incompatible.
 !!! error TS2322:     The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
 !!! error TS2322:       Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
-!!! error TS2322:         Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo> | IteratorReturnResult<any>'.
+!!! error TS2322:         Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
 !!! error TS2322:           Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
 !!! error TS2322:             Type 'Bar | Baz' is not assignable to type 'Foo'.
 !!! error TS2322:               Property 'x' is missing in type 'Baz' but required in type 'Foo'.
diff --git a/tests/baselines/reference/generatorTypeCheck63.errors.txt b/tests/baselines/reference/generatorTypeCheck63.errors.txt
index 4bee87fdb8c..10cafbe0ced 100644
--- a/tests/baselines/reference/generatorTypeCheck63.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck63.errors.txt
@@ -2,7 +2,7 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(24,61): err
   Call signature return types 'Generator<number, State, undefined>' and 'IterableIterator<State>' are incompatible.
     The types returned by 'next(...)' are incompatible between these types.
       Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
-        Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<State>'.
+        Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
             Type 'number' is not assignable to type 'State'.
 
@@ -37,7 +37,7 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(24,61): err
 !!! error TS2345:   Call signature return types 'Generator<number, State, undefined>' and 'IterableIterator<State>' are incompatible.
 !!! error TS2345:     The types returned by 'next(...)' are incompatible between these types.
 !!! error TS2345:       Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
-!!! error TS2345:         Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<State>'.
+!!! error TS2345:         Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
 !!! error TS2345:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
 !!! error TS2345:             Type 'number' is not assignable to type 'State'.
         yield 1;
diff --git a/tests/baselines/reference/generatorTypeCheck8.errors.txt b/tests/baselines/reference/generatorTypeCheck8.errors.txt
index 7ad215c495b..ca0b1e30366 100644
--- a/tests/baselines/reference/generatorTypeCheck8.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck8.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error TS2322: Type 'Generator<string, any, undefined>' is not assignable to type 'BadGenerator'.
   The types returned by 'next(...)' are incompatible between these types.
     Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
-      Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number> | IteratorReturnResult<any>'.
+      Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
         Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
           Type 'string' is not assignable to type 'number'.
 
@@ -13,6 +13,6 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error
 !!! error TS2322: Type 'Generator<string, any, undefined>' is not assignable to type 'BadGenerator'.
 !!! error TS2322:   The types returned by 'next(...)' are incompatible between these types.
 !!! error TS2322:     Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:       Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number> | IteratorReturnResult<any>'.
+!!! error TS2322:       Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
 !!! error TS2322:         Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
 !!! error TS2322:           Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/iterableArrayPattern28.errors.txt b/tests/baselines/reference/iterableArrayPattern28.errors.txt
index ba815996f10..0778b149183 100644
--- a/tests/baselines/reference/iterableArrayPattern28.errors.txt
+++ b/tests/baselines/reference/iterableArrayPattern28.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/es6/destructuring/iterableArrayPattern28.ts(2,24): error
     Argument of type '([string, number] | [string, boolean])[]' is not assignable to parameter of type 'Iterable<readonly [string, number]>'.
       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
         Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-          Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<readonly [string, number]>'.
+          Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
             Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
               Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
                 Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
@@ -22,7 +22,7 @@ tests/cases/conformance/es6/destructuring/iterableArrayPattern28.ts(2,24): error
 !!! error TS2769:     Argument of type '([string, number] | [string, boolean])[]' is not assignable to parameter of type 'Iterable<readonly [string, number]>'.
 !!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
 !!! error TS2769:         Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorReturnResult<any> | IteratorYieldResult<readonly [string, number]>'.
+!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
 !!! error TS2769:             Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
 !!! error TS2769:               Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
 !!! error TS2769:                 Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
diff --git a/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt b/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
index fd8a2a9c2fa..8db42a231ad 100644
--- a/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
+++ b/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts(10,9): error TS2322: Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
-  Object literal may only specify known properties, and 'jj' does not exist in type 'StyleBase | StyleArray'.
+  Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
 
 
 ==== tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts (1 errors) ====
@@ -15,7 +15,7 @@ tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts(10,9): error TS232
             jj: 1 // intentional error
             ~~~~~
 !!! error TS2322: Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
-!!! error TS2322:   Object literal may only specify known properties, and 'jj' does not exist in type 'StyleBase | StyleArray'.
+!!! error TS2322:   Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
         }]]
     ];
     
diff --git a/tests/baselines/reference/numericLiteralTypes3.errors.txt b/tests/baselines/reference/numericLiteralTypes3.errors.txt
index 68a532b2f3d..a9fbb5df915 100644
--- a/tests/baselines/reference/numericLiteralTypes3.errors.txt
+++ b/tests/baselines/reference/numericLiteralTypes3.errors.txt
@@ -6,15 +6,15 @@ tests/cases/conformance/types/literal/numericLiteralTypes3.ts(10,5): error TS232
   Type '0' is not assignable to type '1'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(14,5): error TS2322: Type '1' is not assignable to type 'B'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(16,5): error TS2322: Type 'C' is not assignable to type 'B'.
-  Type '1' is not assignable to type '2 | 3'.
+  Type '1' is not assignable to type 'B'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(17,5): error TS2322: Type 'D' is not assignable to type 'B'.
-  Type '0' is not assignable to type '2 | 3'.
+  Type '0' is not assignable to type 'B'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(24,5): error TS2322: Type 'D' is not assignable to type 'C'.
-  Type '0' is not assignable to type '2 | 3 | 1'.
+  Type '0' is not assignable to type 'C'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(29,5): error TS2322: Type 'B' is not assignable to type 'D'.
-  Type '3' is not assignable to type '0 | 2 | 1'.
+  Type '3' is not assignable to type 'D'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(30,5): error TS2322: Type 'C' is not assignable to type 'D'.
-  Type '3' is not assignable to type '0 | 2 | 1'.
+  Type '3' is not assignable to type 'D'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(35,5): error TS2322: Type '0' is not assignable to type '1'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(37,5): error TS2322: Type '2' is not assignable to type '1'.
 tests/cases/conformance/types/literal/numericLiteralTypes3.ts(38,5): error TS2322: Type '3' is not assignable to type '1'.
@@ -66,11 +66,11 @@ tests/cases/conformance/types/literal/numericLiteralTypes3.ts(98,14): error TS26
         b = c;
         ~
 !!! error TS2322: Type 'C' is not assignable to type 'B'.
-!!! error TS2322:   Type '1' is not assignable to type '2 | 3'.
+!!! error TS2322:   Type '1' is not assignable to type 'B'.
         b = d;
         ~
 !!! error TS2322: Type 'D' is not assignable to type 'B'.
-!!! error TS2322:   Type '0' is not assignable to type '2 | 3'.
+!!! error TS2322:   Type '0' is not assignable to type 'B'.
     }
     
     function f3(a: A, b: B, c: C, d: D) {
@@ -80,7 +80,7 @@ tests/cases/conformance/types/literal/numericLiteralTypes3.ts(98,14): error TS26
         c = d;
         ~
 !!! error TS2322: Type 'D' is not assignable to type 'C'.
-!!! error TS2322:   Type '0' is not assignable to type '2 | 3 | 1'.
+!!! error TS2322:   Type '0' is not assignable to type 'C'.
     }
     
     function f4(a: A, b: B, c: C, d: D) {
@@ -88,11 +88,11 @@ tests/cases/conformance/types/literal/numericLiteralTypes3.ts(98,14): error TS26
         d = b;
         ~
 !!! error TS2322: Type 'B' is not assignable to type 'D'.
-!!! error TS2322:   Type '3' is not assignable to type '0 | 2 | 1'.
+!!! error TS2322:   Type '3' is not assignable to type 'D'.
         d = c;
         ~
 !!! error TS2322: Type 'C' is not assignable to type 'D'.
-!!! error TS2322:   Type '3' is not assignable to type '0 | 2 | 1'.
+!!! error TS2322:   Type '3' is not assignable to type 'D'.
         d = d;
     }
     
diff --git a/tests/baselines/reference/stringEnumLiteralTypes3.errors.txt b/tests/baselines/reference/stringEnumLiteralTypes3.errors.txt
index 865b991caa6..bdb775ae5e6 100644
--- a/tests/baselines/reference/stringEnumLiteralTypes3.errors.txt
+++ b/tests/baselines/reference/stringEnumLiteralTypes3.errors.txt
@@ -4,7 +4,7 @@ tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(11,5): error TS
   Type 'Choice.Unknown' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(12,5): error TS2322: Type 'Choice' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(18,5): error TS2322: Type 'UnknownYesNo' is not assignable to type 'YesNo'.
-  Type 'Choice.Unknown' is not assignable to type 'Choice.Yes | Choice.No'.
+  Type 'Choice.Unknown' is not assignable to type 'YesNo'.
 tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(19,5): error TS2322: Type 'Choice' is not assignable to type 'YesNo'.
 tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(37,5): error TS2322: Type 'Choice.Unknown' is not assignable to type 'Choice.Yes'.
 tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(39,5): error TS2322: Type 'Choice.No' is not assignable to type 'Choice.Yes'.
@@ -46,7 +46,7 @@ tests/cases/conformance/types/literal/stringEnumLiteralTypes3.ts(96,14): error T
         b = c;
         ~
 !!! error TS2322: Type 'UnknownYesNo' is not assignable to type 'YesNo'.
-!!! error TS2322:   Type 'Choice.Unknown' is not assignable to type 'Choice.Yes | Choice.No'.
+!!! error TS2322:   Type 'Choice.Unknown' is not assignable to type 'YesNo'.
         b = d;
         ~
 !!! error TS2322: Type 'Choice' is not assignable to type 'YesNo'.
diff --git a/tests/baselines/reference/tsxSpreadAttributesResolution6.errors.txt b/tests/baselines/reference/tsxSpreadAttributesResolution6.errors.txt
index 0027abe1092..360f8a72ada 100644
--- a/tests/baselines/reference/tsxSpreadAttributesResolution6.errors.txt
+++ b/tests/baselines/reference/tsxSpreadAttributesResolution6.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/jsx/file.tsx(13,10): error TS2322: Type '{ editable: true; }' is not assignable to type '(IntrinsicAttributes & IntrinsicClassAttributes<TextComponent> & { editable: false; } & { children?: ReactNode; }) | (IntrinsicAttributes & IntrinsicClassAttributes<TextComponent> & { editable: true; onEdit: (newText: string) => void; } & { children?: ReactNode; })'.
+tests/cases/conformance/jsx/file.tsx(13,10): error TS2322: Type '{ editable: true; }' is not assignable to type 'IntrinsicAttributes & (IntrinsicClassAttributes<TextComponent> & (TextProps & { children?: ReactNode; }))'.
   Property 'onEdit' is missing in type '{ editable: true; }' but required in type '{ editable: true; onEdit: (newText: string) => void; }'.
 
 
@@ -17,7 +17,7 @@ tests/cases/conformance/jsx/file.tsx(13,10): error TS2322: Type '{ editable: tru
     // Error
     let x = <TextComponent editable={true} />
              ~~~~~~~~~~~~~
-!!! error TS2322: Type '{ editable: true; }' is not assignable to type '(IntrinsicAttributes & IntrinsicClassAttributes<TextComponent> & { editable: false; } & { children?: ReactNode; }) | (IntrinsicAttributes & IntrinsicClassAttributes<TextComponent> & { editable: true; onEdit: (newText: string) => void; } & { children?: ReactNode; })'.
+!!! error TS2322: Type '{ editable: true; }' is not assignable to type 'IntrinsicAttributes & (IntrinsicClassAttributes<TextComponent> & (TextProps & { children?: ReactNode; }))'.
 !!! error TS2322:   Property 'onEdit' is missing in type '{ editable: true; }' but required in type '{ editable: true; onEdit: (newText: string) => void; }'.
 !!! related TS2728 tests/cases/conformance/jsx/file.tsx:4:36: 'onEdit' is declared here.
     
diff --git a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
index 80c87849ff4..443c556fe55 100644
--- a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
+++ b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
@@ -55,7 +55,7 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(128,34
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(132,34): error TS1230: A type predicate cannot reference element 'p1' in a binding pattern.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(136,39): error TS1230: A type predicate cannot reference element 'p1' in a binding pattern.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(152,68): error TS2344: Type 'T | "d"' does not satisfy the constraint 'Keys'.
-  Type '"d"' is not assignable to type '"a" | "b" | "c"'.
+  Type '"d"' is not assignable to type 'Keys'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(159,31): error TS2344: Type 'Bar' does not satisfy the constraint 'Foo'.
   Types of property ''a'' are incompatible.
     Type 'number' is not assignable to type 'string'.
@@ -332,7 +332,7 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(166,54
     declare function hasKey<T extends Keys>(x: KeySet<T>): x is KeySet<T|'d'>;
                                                                        ~~~~~
 !!! error TS2344: Type 'T | "d"' does not satisfy the constraint 'Keys'.
-!!! error TS2344:   Type '"d"' is not assignable to type '"a" | "b" | "c"'.
+!!! error TS2344:   Type '"d"' is not assignable to type 'Keys'.
     
     type Foo = { 'a': string; }
     type Bar = { 'a': number; }
diff --git a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
index db200ed1f0e..6f3a7581e64 100644
--- a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
+++ b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
@@ -5,7 +5,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
     The types returned by 'next(...)' are incompatible between these types.
       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
-          Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number> | IteratorReturnResult<any>'.
+          Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
               Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(13,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
@@ -70,7 +70,7 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 !!! error TS2322:     The types returned by 'next(...)' are incompatible between these types.
 !!! error TS2322:       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 !!! error TS2322:         Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:           Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number> | IteratorReturnResult<any>'.
+!!! error TS2322:           Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
 !!! error TS2322:             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
 !!! error TS2322:               Type 'string' is not assignable to type 'number'.
         yield "a";
diff --git a/tests/baselines/reference/unknownType2.errors.txt b/tests/baselines/reference/unknownType2.errors.txt
index 26939706863..1469526182b 100644
--- a/tests/baselines/reference/unknownType2.errors.txt
+++ b/tests/baselines/reference/unknownType2.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/types/unknown/unknownType2.ts(216,13): error TS2322: Type '"yes" | "no" | "maybe"' is not assignable to type 'SomeResponse'.
-  Type '"maybe"' is not assignable to type '"yes" | "no" | "idk"'.
+  Type '"maybe"' is not assignable to type 'SomeResponse'.
 
 
 ==== tests/cases/conformance/types/unknown/unknownType2.ts (1 errors) ====
@@ -221,7 +221,7 @@ tests/cases/conformance/types/unknown/unknownType2.ts(216,13): error TS2322: Typ
                 return x; // error
                 ~~~~~~~~~
 !!! error TS2322: Type '"yes" | "no" | "maybe"' is not assignable to type 'SomeResponse'.
-!!! error TS2322:   Type '"maybe"' is not assignable to type '"yes" | "no" | "idk"'.
+!!! error TS2322:   Type '"maybe"' is not assignable to type 'SomeResponse'.
             default:
                 throw new Error('Can you repeat the question?');
         }