diff --git a/Jakefile.js b/Jakefile.js
index 31243f77c42..e6ff364e58b 100644
--- a/Jakefile.js
+++ b/Jakefile.js
@@ -1122,14 +1122,15 @@ task("update-sublime", ["local", serverFile], function () {
 
 var tslintRuleDir = "scripts/tslint";
 var tslintRules = [
-    "nextLineRule",
     "booleanTriviaRule",
-    "typeOperatorSpacingRule",
-    "noInOperatorRule",
+    "debugAssertRule",
+    "nextLineRule",
+    "noBomRule",
     "noIncrementDecrementRule",
-    "objectLiteralSurroundingSpaceRule",
+    "noInOperatorRule",
     "noTypeAssertionWhitespaceRule",
-    "noBomRule"
+    "objectLiteralSurroundingSpaceRule",
+    "typeOperatorSpacingRule",
 ];
 var tslintRulesFiles = tslintRules.map(function (p) {
     return path.join(tslintRuleDir, p + ".ts");
diff --git a/scripts/tslint/booleanTriviaRule.ts b/scripts/tslint/booleanTriviaRule.ts
index 189dafac77e..c498131be16 100644
--- a/scripts/tslint/booleanTriviaRule.ts
+++ b/scripts/tslint/booleanTriviaRule.ts
@@ -34,6 +34,7 @@ function walk(ctx: Lint.WalkContext<void>): void {
             switch (methodName) {
                 case "apply":
                 case "assert":
+                case "assertEqual":
                 case "call":
                 case "equal":
                 case "fail":
@@ -69,7 +70,7 @@ function walk(ctx: Lint.WalkContext<void>): void {
 
         const ranges = ts.getTrailingCommentRanges(sourceFile.text, arg.pos) || ts.getLeadingCommentRanges(sourceFile.text, arg.pos);
         if (ranges === undefined || ranges.length !== 1 || ranges[0].kind !== ts.SyntaxKind.MultiLineCommentTrivia) {
-            ctx.addFailureAtNode(arg, "Tag boolean argument with parameter name");
+            ctx.addFailureAtNode(arg, "Tag argument with parameter name");
             return;
         }
 
diff --git a/scripts/tslint/debugAssertRule.ts b/scripts/tslint/debugAssertRule.ts
new file mode 100644
index 00000000000..933b27697b0
--- /dev/null
+++ b/scripts/tslint/debugAssertRule.ts
@@ -0,0 +1,45 @@
+import * as Lint from "tslint/lib";
+import * as ts from "typescript";
+
+export class Rule extends Lint.Rules.AbstractRule {
+    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+        return this.applyWithFunction(sourceFile, ctx => walk(ctx));
+    }
+}
+
+function walk(ctx: Lint.WalkContext<void>): void {
+    ts.forEachChild(ctx.sourceFile, function recur(node) {
+        if (ts.isCallExpression(node)) {
+            checkCall(node);
+        }
+        ts.forEachChild(node, recur);
+    });
+
+    function checkCall(node: ts.CallExpression) {
+        if (!isDebugAssert(node.expression) || node.arguments.length < 2) {
+            return;
+        }
+
+        const message = node.arguments[1];
+        if (!ts.isStringLiteral(message)) {
+            ctx.addFailureAtNode(message, "Second argument to 'Debug.assert' should be a string literal.");
+        }
+
+        if (node.arguments.length < 3) {
+            return;
+        }
+
+        const message2 = node.arguments[2];
+        if (!ts.isStringLiteral(message2) && !ts.isArrowFunction(message2)) {
+            ctx.addFailureAtNode(message, "Third argument to 'Debug.assert' should be a string literal or arrow function.");
+        }
+    }
+
+    function isDebugAssert(expr: ts.Node): boolean {
+        return ts.isPropertyAccessExpression(expr) && isName(expr.expression, "Debug") && isName(expr.name, "assert");
+    }
+
+    function isName(expr: ts.Node, text: string): boolean {
+        return ts.isIdentifier(expr) && expr.text === text;
+    }
+}
diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 2fbd0c3e141..45880f855fd 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -2921,7 +2921,10 @@ namespace ts {
     function computeCatchClause(node: CatchClause, subtreeFlags: TransformFlags) {
         let transformFlags = subtreeFlags;
 
-        if (node.variableDeclaration && isBindingPattern(node.variableDeclaration.name)) {
+        if (!node.variableDeclaration) {
+            transformFlags |= TransformFlags.AssertESNext;
+        }
+        else if (isBindingPattern(node.variableDeclaration.name)) {
             transformFlags |= TransformFlags.AssertES2015;
         }
 
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 10400a3853a..1d1d16b7ee1 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -481,7 +481,7 @@ namespace ts {
             Type,
             ResolvedBaseConstructorType,
             DeclaredType,
-            ResolvedReturnType
+            ResolvedReturnType,
         }
 
         const enum CheckMode {
@@ -1086,7 +1086,10 @@ namespace ts {
                 location = location.parent;
             }
 
-            if (result && nameNotFoundMessage && noUnusedIdentifiers) {
+            // We just climbed up parents looking for the name, meaning that we started in a descendant node of `lastLocation`.
+            // If `result === lastLocation.symbol`, that means that we are somewhere inside `lastLocation` looking up a name, and resolving to `lastLocation` itself.
+            // That means that this is a self-reference of `lastLocation`, and shouldn't count this when considering whether `lastLocation` is used.
+            if (result && nameNotFoundMessage && noUnusedIdentifiers && result !== lastLocation.symbol) {
                 result.isReferenced = true;
             }
 
@@ -1754,7 +1757,7 @@ namespace ts {
         // An external module with an 'export =' declaration resolves to the target of the 'export =' declaration,
         // and an external module with no 'export =' declaration resolves to the module itself.
         function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol {
-            return moduleSymbol && getMergedSymbol(resolveSymbol(moduleSymbol.exports.get("export=" as __String), dontResolveAlias)) || moduleSymbol;
+            return moduleSymbol && getMergedSymbol(resolveSymbol(moduleSymbol.exports.get(InternalSymbolName.ExportEquals), dontResolveAlias)) || moduleSymbol;
         }
 
         // An external module with an 'export =' declaration may be referenced as an ES6 module provided the 'export ='
@@ -1769,7 +1772,7 @@ namespace ts {
         }
 
         function hasExportAssignmentSymbol(moduleSymbol: Symbol): boolean {
-            return moduleSymbol.exports.get("export=" as __String) !== undefined;
+            return moduleSymbol.exports.get(InternalSymbolName.ExportEquals) !== undefined;
         }
 
         function getExportsOfModuleAsArray(moduleSymbol: Symbol): Symbol[] {
@@ -3417,9 +3420,7 @@ namespace ts {
                             if (!symbolStack) {
                                 symbolStack = [];
                             }
-                            const isConstructorObject = type.flags & TypeFlags.Object &&
-                                getObjectFlags(type) & ObjectFlags.Anonymous &&
-                                type.symbol && type.symbol.flags & SymbolFlags.Class;
+                            const isConstructorObject = type.objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & SymbolFlags.Class;
                             if (isConstructorObject) {
                                 writeLiteralType(type, flags);
                             }
@@ -7555,11 +7556,11 @@ namespace ts {
                     return getTypeOfSymbol(prop);
                 }
             }
-            if (isTypeAnyOrAllConstituentTypesHaveKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbol)) {
+            if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbol)) {
                 if (isTypeAny(objectType)) {
                     return anyType;
                 }
-                const indexInfo = isTypeAnyOrAllConstituentTypesHaveKind(indexType, TypeFlags.NumberLike) && getIndexInfoOfType(objectType, IndexKind.Number) ||
+                const indexInfo = isTypeAssignableToKind(indexType, TypeFlags.NumberLike) && getIndexInfoOfType(objectType, IndexKind.Number) ||
                     getIndexInfoOfType(objectType, IndexKind.String) ||
                     undefined;
                 if (indexInfo) {
@@ -8938,11 +8939,21 @@ namespace ts {
                     !(target.flags & TypeFlags.Union) &&
                     !isIntersectionConstituent &&
                     source !== globalObjectType &&
-                    getPropertiesOfType(source).length > 0 &&
+                    (getPropertiesOfType(source).length > 0 ||
+                     getSignaturesOfType(source, SignatureKind.Call).length > 0 ||
+                     getSignaturesOfType(source, SignatureKind.Construct).length > 0) &&
                     isWeakType(target) &&
                     !hasCommonProperties(source, target)) {
                     if (reportErrors) {
-                        reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, typeToString(source), typeToString(target));
+                        const calls = getSignaturesOfType(source, SignatureKind.Call);
+                        const constructs = getSignaturesOfType(source, SignatureKind.Construct);
+                        if (calls.length > 0 && isRelatedTo(getReturnTypeOfSignature(calls[0]), target, /*reportErrors*/ false) ||
+                            constructs.length > 0 && isRelatedTo(getReturnTypeOfSignature(constructs[0]), target, /*reportErrors*/ false)) {
+                            reportError(Diagnostics.Value_of_type_0_has_no_properties_in_common_with_type_1_Did_you_mean_to_call_it, typeToString(source), typeToString(target));
+                        }
+                        else {
+                            reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, typeToString(source), typeToString(target));
+                        }
                     }
                     return Ternary.False;
                 }
@@ -10800,17 +10811,6 @@ namespace ts {
             return undefined;
         }
 
-        function getLeftmostIdentifierOrThis(node: Node): Node {
-            switch (node.kind) {
-                case SyntaxKind.Identifier:
-                case SyntaxKind.ThisKeyword:
-                    return node;
-                case SyntaxKind.PropertyAccessExpression:
-                    return getLeftmostIdentifierOrThis((<PropertyAccessExpression>node).expression);
-            }
-            return undefined;
-        }
-
         function getBindingElementNameText(element: BindingElement): string | undefined {
             if (element.parent.kind === SyntaxKind.ObjectBindingPattern) {
                 const name = element.propertyName || element.name;
@@ -11384,7 +11384,7 @@ namespace ts {
                 (<BinaryExpression>parent.parent).operatorToken.kind === SyntaxKind.EqualsToken &&
                 (<BinaryExpression>parent.parent).left === parent &&
                 !isAssignmentTarget(parent.parent) &&
-                isTypeAnyOrAllConstituentTypesHaveKind(getTypeOfExpression((<ElementAccessExpression>parent).argumentExpression), TypeFlags.NumberLike | TypeFlags.Undefined);
+                isTypeAssignableToKind(getTypeOfExpression((<ElementAccessExpression>parent).argumentExpression), TypeFlags.NumberLike);
             return isLengthPushOrUnshift || isElementAssignment;
         }
 
@@ -11556,7 +11556,7 @@ namespace ts {
                         }
                         else {
                             const indexType = getTypeOfExpression((<ElementAccessExpression>(<BinaryExpression>node).left).argumentExpression);
-                            if (isTypeAnyOrAllConstituentTypesHaveKind(indexType, TypeFlags.NumberLike | TypeFlags.Undefined)) {
+                            if (isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) {
                                 evolvedType = addEvolvingArrayElementType(evolvedType, (<BinaryExpression>node).right);
                             }
                         }
@@ -13398,11 +13398,7 @@ namespace ts {
         function isNumericComputedName(name: ComputedPropertyName): boolean {
             // It seems odd to consider an expression of type Any to result in a numeric name,
             // but this behavior is consistent with checkIndexedAccess
-            return isTypeAnyOrAllConstituentTypesHaveKind(checkComputedPropertyName(name), TypeFlags.NumberLike);
-        }
-
-        function isTypeAnyOrAllConstituentTypesHaveKind(type: Type, kind: TypeFlags): boolean {
-            return isTypeAny(type) || isTypeOfKind(type, kind);
+            return isTypeAssignableToKind(checkComputedPropertyName(name), TypeFlags.NumberLike);
         }
 
         function isInfinityOrNaNString(name: string | __String): boolean {
@@ -13438,10 +13434,11 @@ namespace ts {
             const links = getNodeLinks(node.expression);
             if (!links.resolvedType) {
                 links.resolvedType = checkExpression(node.expression);
-
                 // This will allow types number, string, symbol or any. It will also allow enums, the unknown
                 // type, and any union of these types (like string | number).
-                if (!isTypeAnyOrAllConstituentTypesHaveKind(links.resolvedType, TypeFlags.NumberLike | TypeFlags.StringLike | TypeFlags.ESSymbol)) {
+                if (links.resolvedType.flags & TypeFlags.Nullable ||
+                    !isTypeAssignableToKind(links.resolvedType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbol) &&
+                    !isTypeAssignableTo(links.resolvedType, getUnionType([stringType, numberType, esSymbolType]))) {
                     error(node, Diagnostics.A_computed_property_name_must_be_of_type_string_number_symbol_or_any);
                 }
                 else {
@@ -14105,11 +14102,8 @@ namespace ts {
          */
         function resolveCustomJsxElementAttributesType(openingLikeElement: JsxOpeningLikeElement,
             shouldIncludeAllStatelessAttributesType: boolean,
-            elementType?: Type,
+            elementType: Type = checkExpression(openingLikeElement.tagName),
             elementClassType?: Type): Type {
-            if (!elementType) {
-                elementType = checkExpression(openingLikeElement.tagName);
-            }
 
             if (elementType.flags & TypeFlags.Union) {
                 const types = (elementType as UnionType).types;
@@ -14243,11 +14237,12 @@ namespace ts {
          */
         function getCustomJsxElementAttributesType(node: JsxOpeningLikeElement, shouldIncludeAllStatelessAttributesType: boolean): Type {
             const links = getNodeLinks(node);
-            if (!links.resolvedJsxElementAttributesType) {
+            const linkLocation = shouldIncludeAllStatelessAttributesType ? "resolvedJsxElementAllAttributesType" : "resolvedJsxElementAttributesType";
+            if (!links[linkLocation]) {
                 const elemClassType = getJsxGlobalElementClassType();
-                return links.resolvedJsxElementAttributesType = resolveCustomJsxElementAttributesType(node, shouldIncludeAllStatelessAttributesType, /*elementType*/ undefined, elemClassType);
+                return links[linkLocation] = resolveCustomJsxElementAttributesType(node, shouldIncludeAllStatelessAttributesType, /*elementType*/ undefined, elemClassType);
             }
-            return links.resolvedJsxElementAttributesType;
+            return links[linkLocation];
         }
 
         /**
@@ -15548,7 +15543,7 @@ namespace ts {
 
                     case SyntaxKind.ComputedPropertyName:
                         const nameType = checkComputedPropertyName(element.name);
-                        if (isTypeOfKind(nameType, TypeFlags.ESSymbol)) {
+                        if (isTypeAssignableToKind(nameType, TypeFlags.ESSymbol)) {
                             return nameType;
                         }
                         else {
@@ -16407,12 +16402,35 @@ namespace ts {
             if (moduleSymbol) {
                 const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontRecursivelyResolve*/ true);
                 if (esModuleSymbol) {
-                    return createPromiseReturnType(node, getTypeOfSymbol(esModuleSymbol));
+                    return createPromiseReturnType(node, getTypeWithSyntheticDefaultImportType(getTypeOfSymbol(esModuleSymbol), esModuleSymbol));
                 }
             }
             return createPromiseReturnType(node, anyType);
         }
 
+        function getTypeWithSyntheticDefaultImportType(type: Type, symbol: Symbol): Type {
+            if (allowSyntheticDefaultImports && type && type !== unknownType) {
+                const synthType = type as SyntheticDefaultModuleType;
+                if (!synthType.syntheticType) {
+                    if (!getPropertyOfType(type, InternalSymbolName.Default)) {
+                        const memberTable = createSymbolTable();
+                        const newSymbol = createSymbol(SymbolFlags.Alias, InternalSymbolName.Default);
+                        newSymbol.target = resolveSymbol(symbol);
+                        memberTable.set(InternalSymbolName.Default, newSymbol);
+                        const anonymousSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type);
+                        const defaultContainingObject = createAnonymousType(anonymousSymbol, memberTable, emptyArray, emptyArray, /*stringIndexInfo*/ undefined, /*numberIndexInfo*/ undefined);
+                        anonymousSymbol.type = defaultContainingObject;
+                        synthType.syntheticType = getIntersectionType([type, defaultContainingObject]);
+                    }
+                    else {
+                        synthType.syntheticType = type;
+                    }
+                }
+                return synthType.syntheticType;
+            }
+            return type;
+        }
+
         function isCommonJsRequire(node: Node) {
             if (!isRequireCall(node, /*checkArgumentIsStringLiteral*/ true)) {
                 return false;
@@ -16938,7 +16956,7 @@ namespace ts {
         }
 
         function checkArithmeticOperandType(operand: Node, type: Type, diagnostic: DiagnosticMessage): boolean {
-            if (!isTypeAnyOrAllConstituentTypesHaveKind(type, TypeFlags.NumberLike)) {
+            if (!isTypeAssignableToKind(type, TypeFlags.NumberLike)) {
                 error(operand, diagnostic);
                 return false;
             }
@@ -17116,31 +17134,22 @@ namespace ts {
             return false;
         }
 
-        // Return true if type is of the given kind. A union type is of a given kind if all constituent types
-        // are of the given kind. An intersection type is of a given kind if at least one constituent type is
-        // of the given kind.
-        function isTypeOfKind(type: Type, kind: TypeFlags): boolean {
-            if (type.flags & kind) {
+        function isTypeAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean {
+            if (source.flags & kind) {
                 return true;
             }
-            if (type.flags & TypeFlags.Union) {
-                const types = (<UnionOrIntersectionType>type).types;
-                for (const t of types) {
-                    if (!isTypeOfKind(t, kind)) {
-                        return false;
-                    }
-                }
-                return true;
+            if (strict && source.flags & (TypeFlags.Any | TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null)) {
+                return false;
             }
-            if (type.flags & TypeFlags.Intersection) {
-                const types = (<UnionOrIntersectionType>type).types;
-                for (const t of types) {
-                    if (isTypeOfKind(t, kind)) {
-                        return true;
-                    }
-                }
-            }
-            return false;
+            return (kind & TypeFlags.NumberLike && isTypeAssignableTo(source, numberType)) ||
+                (kind & TypeFlags.StringLike && isTypeAssignableTo(source, stringType)) ||
+                (kind & TypeFlags.BooleanLike && isTypeAssignableTo(source, booleanType)) ||
+                (kind & TypeFlags.Void && isTypeAssignableTo(source, voidType)) ||
+                (kind & TypeFlags.Never && isTypeAssignableTo(source, neverType)) ||
+                (kind & TypeFlags.Null && isTypeAssignableTo(source, nullType)) ||
+                (kind & TypeFlags.Undefined && isTypeAssignableTo(source, undefinedType)) ||
+                (kind & TypeFlags.ESSymbol && isTypeAssignableTo(source, esSymbolType)) ||
+                (kind & TypeFlags.NonPrimitive && isTypeAssignableTo(source, nonPrimitiveType));
         }
 
         function isConstEnumObjectType(type: Type): boolean {
@@ -17160,7 +17169,7 @@ namespace ts {
             // and the right operand to be of type Any, a subtype of the 'Function' interface type, or have a call or construct signature.
             // The result is always of the Boolean primitive type.
             // NOTE: do not raise error if leftType is unknown as related error was already reported
-            if (isTypeOfKind(leftType, TypeFlags.Primitive)) {
+            if (!isTypeAny(leftType) && isTypeAssignableToKind(leftType, TypeFlags.Primitive)) {
                 error(left, Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter);
             }
             // NOTE: do not raise error if right is unknown as related error was already reported
@@ -17183,10 +17192,10 @@ namespace ts {
             // The in operator requires the left operand to be of type Any, the String primitive type, or the Number primitive type,
             // and the right operand to be of type Any, an object type, or a type parameter type.
             // The result is always of the Boolean primitive type.
-            if (!(isTypeComparableTo(leftType, stringType) || isTypeOfKind(leftType, TypeFlags.NumberLike | TypeFlags.ESSymbol))) {
+            if (!(isTypeComparableTo(leftType, stringType) || isTypeAssignableToKind(leftType, TypeFlags.NumberLike | TypeFlags.ESSymbol))) {
                 error(left, Diagnostics.The_left_hand_side_of_an_in_expression_must_be_of_type_any_string_number_or_symbol);
             }
-            if (!isTypeAnyOrAllConstituentTypesHaveKind(rightType, TypeFlags.Object | TypeFlags.TypeVariable | TypeFlags.NonPrimitive)) {
+            if (!isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.TypeVariable)) {
                 error(right, Diagnostics.The_right_hand_side_of_an_in_expression_must_be_of_type_any_an_object_type_or_a_type_parameter);
             }
             return booleanType;
@@ -17495,32 +17504,30 @@ namespace ts {
                         return silentNeverType;
                     }
 
-                    if (!isTypeOfKind(leftType, TypeFlags.Any | TypeFlags.StringLike) && !isTypeOfKind(rightType, TypeFlags.Any | TypeFlags.StringLike)) {
+                    if (!isTypeAssignableToKind(leftType, TypeFlags.StringLike) && !isTypeAssignableToKind(rightType, TypeFlags.StringLike)) {
                         leftType = checkNonNullType(leftType, left);
                         rightType = checkNonNullType(rightType, right);
                     }
 
                     let resultType: Type;
-                    if (isTypeOfKind(leftType, TypeFlags.NumberLike) && isTypeOfKind(rightType, TypeFlags.NumberLike)) {
+                    if (isTypeAssignableToKind(leftType, TypeFlags.NumberLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.NumberLike, /*strict*/ true)) {
                         // Operands of an enum type are treated as having the primitive type Number.
                         // If both operands are of the Number primitive type, the result is of the Number primitive type.
                         resultType = numberType;
                     }
-                    else {
-                        if (isTypeOfKind(leftType, TypeFlags.StringLike) || isTypeOfKind(rightType, TypeFlags.StringLike)) {
+                    else if (isTypeAssignableToKind(leftType, TypeFlags.StringLike, /*strict*/ true) || isTypeAssignableToKind(rightType, TypeFlags.StringLike, /*strict*/ true)) {
                             // If one or both operands are of the String primitive type, the result is of the String primitive type.
                             resultType = stringType;
-                        }
-                        else if (isTypeAny(leftType) || isTypeAny(rightType)) {
-                            // Otherwise, the result is of type Any.
-                            // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we.
-                            resultType = leftType === unknownType || rightType === unknownType ? unknownType : anyType;
-                        }
+                    }
+                    else if (isTypeAny(leftType) || isTypeAny(rightType)) {
+                        // Otherwise, the result is of type Any.
+                        // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we.
+                        resultType = leftType === unknownType || rightType === unknownType ? unknownType : anyType;
+                    }
 
-                        // Symbols are not allowed at all in arithmetic expressions
-                        if (resultType && !checkForDisallowedESSymbolOperand(operator)) {
-                            return resultType;
-                        }
+                    // Symbols are not allowed at all in arithmetic expressions
+                    if (resultType && !checkForDisallowedESSymbolOperand(operator)) {
+                        return resultType;
                     }
 
                     if (!resultType) {
@@ -18520,15 +18527,6 @@ namespace ts {
                 return forEachChild(n, containsSuperCall);
             }
 
-            function markThisReferencesAsErrors(n: Node): void {
-                if (n.kind === SyntaxKind.ThisKeyword) {
-                    error(n, Diagnostics.this_cannot_be_referenced_in_current_location);
-                }
-                else if (n.kind !== SyntaxKind.FunctionExpression && n.kind !== SyntaxKind.FunctionDeclaration) {
-                    forEachChild(n, markThisReferencesAsErrors);
-                }
-            }
-
             function isInstancePropertyWithInitializer(n: Node): boolean {
                 return n.kind === SyntaxKind.PropertyDeclaration &&
                     !(getModifierFlags(n) & ModifierFlags.Static) &&
@@ -18743,7 +18741,7 @@ namespace ts {
             }
             // Check if we're indexing with a numeric type and the object type is a generic
             // type with a constraint that has a numeric index signature.
-            if (maybeTypeOfKind(objectType, TypeFlags.TypeVariable) && isTypeOfKind(indexType, TypeFlags.NumberLike)) {
+            if (maybeTypeOfKind(objectType, TypeFlags.TypeVariable) && isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) {
                 const constraint = getBaseConstraintOfType(objectType);
                 if (constraint && getIndexInfoOfType(constraint, IndexKind.Number)) {
                     return type;
@@ -20450,7 +20448,7 @@ namespace ts {
 
             // unknownType is returned i.e. if node.expression is identifier whose name cannot be resolved
             // in this case error about missing name is already reported - do not report extra one
-            if (!isTypeAnyOrAllConstituentTypesHaveKind(rightType, TypeFlags.Object | TypeFlags.TypeVariable | TypeFlags.NonPrimitive)) {
+            if (!isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.TypeVariable)) {
                 error(node.expression, Diagnostics.The_right_hand_side_of_a_for_in_statement_must_be_of_type_any_an_object_type_or_a_type_parameter);
             }
 
@@ -23437,22 +23435,22 @@ namespace ts {
             else if (type.flags & TypeFlags.Any) {
                 return TypeReferenceSerializationKind.ObjectType;
             }
-            else if (isTypeOfKind(type, TypeFlags.Void | TypeFlags.Nullable | TypeFlags.Never)) {
+            else if (isTypeAssignableToKind(type, TypeFlags.Void | TypeFlags.Nullable | TypeFlags.Never)) {
                 return TypeReferenceSerializationKind.VoidNullableOrNeverType;
             }
-            else if (isTypeOfKind(type, TypeFlags.BooleanLike)) {
+            else if (isTypeAssignableToKind(type, TypeFlags.BooleanLike)) {
                 return TypeReferenceSerializationKind.BooleanType;
             }
-            else if (isTypeOfKind(type, TypeFlags.NumberLike)) {
+            else if (isTypeAssignableToKind(type, TypeFlags.NumberLike)) {
                 return TypeReferenceSerializationKind.NumberLikeType;
             }
-            else if (isTypeOfKind(type, TypeFlags.StringLike)) {
+            else if (isTypeAssignableToKind(type, TypeFlags.StringLike)) {
                 return TypeReferenceSerializationKind.StringLikeType;
             }
             else if (isTupleType(type)) {
                 return TypeReferenceSerializationKind.ArrayLikeType;
             }
-            else if (isTypeOfKind(type, TypeFlags.ESSymbol)) {
+            else if (isTypeAssignableToKind(type, TypeFlags.ESSymbol)) {
                 return TypeReferenceSerializationKind.ESSymbolType;
             }
             else if (isFunctionType(type)) {
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 554b46dcdfe..e82e70dc764 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1446,14 +1446,10 @@ namespace ts {
                 }
             }
             else {
-                // If no includes were specified, exclude common package folders and the outDir
-                const specs = includeSpecs ? [] : ["node_modules", "bower_components", "jspm_packages"];
-
                 const outDir = raw["compilerOptions"] && raw["compilerOptions"]["outDir"];
                 if (outDir) {
-                    specs.push(outDir);
+                    excludeSpecs = [outDir];
                 }
-                excludeSpecs = specs;
             }
 
             if (fileNames === undefined && includeSpecs === undefined) {
@@ -2015,23 +2011,13 @@ namespace ts {
     }
 
     function validateSpecs(specs: ReadonlyArray<string>, errors: Push<Diagnostic>, allowTrailingRecursion: boolean, jsonSourceFile: JsonSourceFile, specKey: string) {
-        const validSpecs: string[] = [];
-        for (const spec of specs) {
-            if (!allowTrailingRecursion && invalidTrailingRecursionPattern.test(spec)) {
-                errors.push(createDiagnostic(Diagnostics.File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0, spec));
+        return specs.filter(spec => {
+            const diag = specToDiagnostic(spec, allowTrailingRecursion);
+            if (diag !== undefined) {
+                errors.push(createDiagnostic(diag, spec));
             }
-            else if (invalidMultipleRecursionPatterns.test(spec)) {
-                errors.push(createDiagnostic(Diagnostics.File_specification_cannot_contain_multiple_recursive_directory_wildcards_Asterisk_Asterisk_Colon_0, spec));
-            }
-            else if (invalidDotDotAfterRecursiveWildcardPattern.test(spec)) {
-                errors.push(createDiagnostic(Diagnostics.File_specification_cannot_contain_a_parent_directory_that_appears_after_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0, spec));
-            }
-            else {
-                validSpecs.push(spec);
-            }
-        }
-
-        return validSpecs;
+            return diag === undefined;
+        });
 
         function createDiagnostic(message: DiagnosticMessage, spec: string): Diagnostic {
             if (jsonSourceFile && jsonSourceFile.jsonObject) {
@@ -2049,6 +2035,18 @@ namespace ts {
         }
     }
 
+    function specToDiagnostic(spec: string, allowTrailingRecursion: boolean): ts.DiagnosticMessage | undefined {
+        if (!allowTrailingRecursion && invalidTrailingRecursionPattern.test(spec)) {
+            return Diagnostics.File_specification_cannot_end_in_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0;
+        }
+        else if (invalidMultipleRecursionPatterns.test(spec)) {
+            return Diagnostics.File_specification_cannot_contain_multiple_recursive_directory_wildcards_Asterisk_Asterisk_Colon_0;
+        }
+        else if (invalidDotDotAfterRecursiveWildcardPattern.test(spec)) {
+            return Diagnostics.File_specification_cannot_contain_a_parent_directory_that_appears_after_a_recursive_directory_wildcard_Asterisk_Asterisk_Colon_0;
+        }
+    }
+
     /**
      * Gets directories in a set of include patterns that should be watched for changes.
      */
diff --git a/src/compiler/comments.ts b/src/compiler/comments.ts
index 06285309f64..50d706d3c42 100644
--- a/src/compiler/comments.ts
+++ b/src/compiler/comments.ts
@@ -8,7 +8,7 @@ namespace ts {
         setWriter(writer: EmitTextWriter): void;
         emitNodeWithComments(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void): void;
         emitBodyWithDetachedComments(node: Node, detachedRange: TextRange, emitCallback: (node: Node) => void): void;
-        emitTrailingCommentsOfPosition(pos: number): void;
+        emitTrailingCommentsOfPosition(pos: number, prefixSpace?: boolean): void;
         emitLeadingCommentsOfPosition(pos: number): void;
     }
 
@@ -306,7 +306,7 @@ namespace ts {
             }
         }
 
-        function emitTrailingCommentsOfPosition(pos: number) {
+        function emitTrailingCommentsOfPosition(pos: number, prefixSpace?: boolean) {
             if (disabled) {
                 return;
             }
@@ -315,7 +315,7 @@ namespace ts {
                 performance.mark("beforeEmitTrailingCommentsOfPosition");
             }
 
-            forEachTrailingCommentToEmit(pos, emitTrailingCommentOfPosition);
+            forEachTrailingCommentToEmit(pos, prefixSpace ? emitTrailingComment : emitTrailingCommentOfPosition);
 
             if (extendedDiagnostics) {
                 performance.measure("commentTime", "beforeEmitTrailingCommentsOfPosition");
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 262564813e9..d5c8396d06d 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -361,11 +361,11 @@ namespace ts {
         return false;
     }
 
-    export function filterMutate<T>(array: T[], f: (x: T) => boolean): void {
+    export function filterMutate<T>(array: T[], f: (x: T, i: number, array: T[]) => boolean): void {
         let outIndex = 0;
-        for (const item of array) {
-            if (f(item)) {
-                array[outIndex] = item;
+        for (let i = 0; i < array.length; i++) {
+            if (f(array[i], i, array)) {
+                array[outIndex] = array[i];
                 outIndex++;
             }
         }
@@ -1290,12 +1290,12 @@ namespace ts {
     export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage): Diagnostic {
         const end = start + length;
 
-        Debug.assert(start >= 0, "start must be non-negative, is " + start);
-        Debug.assert(length >= 0, "length must be non-negative, is " + length);
+        Debug.assertGreaterThanOrEqual(start, 0);
+        Debug.assertGreaterThanOrEqual(length, 0);
 
         if (file) {
-            Debug.assert(start <= file.text.length, `start must be within the bounds of the file. ${start} > ${file.text.length}`);
-            Debug.assert(end <= file.text.length, `end must be the bounds of the file. ${end} > ${file.text.length}`);
+            Debug.assertLessThanOrEqual(start, file.text.length);
+            Debug.assertLessThanOrEqual(end, file.text.length);
         }
 
         let text = getLocaleSpecificMessage(message);
@@ -1875,14 +1875,54 @@ namespace ts {
     const reservedCharacterPattern = /[^\w\s\/]/g;
     const wildcardCharCodes = [CharacterCodes.asterisk, CharacterCodes.question];
 
-    /**
-     * Matches any single directory segment unless it is the last segment and a .min.js file
-     * Breakdown:
-     *  [^./]                   # matches everything up to the first . character (excluding directory seperators)
-     *  (\\.(?!min\\.js$))?     # matches . characters but not if they are part of the .min.js file extension
-     */
-    const singleAsteriskRegexFragmentFiles = "([^./]|(\\.(?!min\\.js$))?)*";
-    const singleAsteriskRegexFragmentOther = "[^/]*";
+    /* @internal */
+    export const commonPackageFolders: ReadonlyArray<string> = ["node_modules", "bower_components", "jspm_packages"];
+
+    const implicitExcludePathRegexPattern = `(?!(${commonPackageFolders.join("|")})(/|$))`;
+
+    interface WildcardMatcher {
+        singleAsteriskRegexFragment: string;
+        doubleAsteriskRegexFragment: string;
+        replaceWildcardCharacter: (match: string) => string;
+    }
+
+    const filesMatcher: WildcardMatcher = {
+        /**
+         * Matches any single directory segment unless it is the last segment and a .min.js file
+         * Breakdown:
+         *  [^./]                   # matches everything up to the first . character (excluding directory seperators)
+         *  (\\.(?!min\\.js$))?     # matches . characters but not if they are part of the .min.js file extension
+         */
+        singleAsteriskRegexFragment: "([^./]|(\\.(?!min\\.js$))?)*",
+        /**
+         * Regex for the ** wildcard. Matches any number of subdirectories. When used for including
+         * files or directories, does not match subdirectories that start with a . character
+         */
+        doubleAsteriskRegexFragment: `(/${implicitExcludePathRegexPattern}[^/.][^/]*)*?`,
+        replaceWildcardCharacter: match => replaceWildcardCharacter(match, filesMatcher.singleAsteriskRegexFragment)
+    };
+
+    const directoriesMatcher: WildcardMatcher = {
+        singleAsteriskRegexFragment: "[^/]*",
+        /**
+         * Regex for the ** wildcard. Matches any number of subdirectories. When used for including
+         * files or directories, does not match subdirectories that start with a . character
+         */
+        doubleAsteriskRegexFragment: `(/${implicitExcludePathRegexPattern}[^/.][^/]*)*?`,
+        replaceWildcardCharacter: match => replaceWildcardCharacter(match, directoriesMatcher.singleAsteriskRegexFragment)
+    };
+
+    const excludeMatcher: WildcardMatcher = {
+        singleAsteriskRegexFragment: "[^/]*",
+        doubleAsteriskRegexFragment: "(/.+?)?",
+        replaceWildcardCharacter: match => replaceWildcardCharacter(match, excludeMatcher.singleAsteriskRegexFragment)
+    };
+
+    const wildcardMatchers = {
+        files: filesMatcher,
+        directories: directoriesMatcher,
+        exclude: excludeMatcher
+    };
 
     export function getRegularExpressionForWildcard(specs: ReadonlyArray<string>, basePath: string, usage: "files" | "directories" | "exclude"): string | undefined {
         const patterns = getRegularExpressionsForWildcards(specs, basePath, usage);
@@ -1901,17 +1941,8 @@ namespace ts {
             return undefined;
         }
 
-        const replaceWildcardCharacter = usage === "files" ? replaceWildCardCharacterFiles : replaceWildCardCharacterOther;
-        const singleAsteriskRegexFragment = usage === "files" ? singleAsteriskRegexFragmentFiles : singleAsteriskRegexFragmentOther;
-
-        /**
-         * Regex for the ** wildcard. Matches any number of subdirectories. When used for including
-         * files or directories, does not match subdirectories that start with a . character
-         */
-        const doubleAsteriskRegexFragment = usage === "exclude" ? "(/.+?)?" : "(/[^/.][^/]*)*?";
-
         return flatMap(specs, spec =>
-            spec && getSubPatternFromSpec(spec, basePath, usage, singleAsteriskRegexFragment, doubleAsteriskRegexFragment, replaceWildcardCharacter));
+            spec && getSubPatternFromSpec(spec, basePath, usage, wildcardMatchers[usage]));
     }
 
     /**
@@ -1922,7 +1953,7 @@ namespace ts {
         return !/[.*?]/.test(lastPathComponent);
     }
 
-    function getSubPatternFromSpec(spec: string, basePath: string, usage: "files" | "directories" | "exclude", singleAsteriskRegexFragment: string, doubleAsteriskRegexFragment: string, replaceWildcardCharacter: (match: string) => string): string | undefined {
+    function getSubPatternFromSpec(spec: string, basePath: string, usage: "files" | "directories" | "exclude", { singleAsteriskRegexFragment, doubleAsteriskRegexFragment, replaceWildcardCharacter }: WildcardMatcher): string | undefined {
         let subpattern = "";
         let hasRecursiveDirectoryWildcard = false;
         let hasWrittenComponent = false;
@@ -1961,20 +1992,36 @@ namespace ts {
                 }
 
                 if (usage !== "exclude") {
+                    let componentPattern = "";
                     // The * and ? wildcards should not match directories or files that start with . if they
                     // appear first in a component. Dotted directories and files can be included explicitly
                     // like so: **/.*/.*
                     if (component.charCodeAt(0) === CharacterCodes.asterisk) {
-                        subpattern += "([^./]" + singleAsteriskRegexFragment + ")?";
+                        componentPattern += "([^./]" + singleAsteriskRegexFragment + ")?";
                         component = component.substr(1);
                     }
                     else if (component.charCodeAt(0) === CharacterCodes.question) {
-                        subpattern += "[^./]";
+                        componentPattern += "[^./]";
                         component = component.substr(1);
                     }
-                }
 
-                subpattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
+                    componentPattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
+
+                    // Patterns should not include subfolders like node_modules unless they are
+                    // explicitly included as part of the path.
+                    //
+                    // As an optimization, if the component pattern is the same as the component,
+                    // then there definitely were no wildcard characters and we do not need to
+                    // add the exclusion pattern.
+                    if (componentPattern !== component) {
+                        subpattern += implicitExcludePathRegexPattern;
+                    }
+
+                    subpattern += componentPattern;
+                }
+                else {
+                    subpattern += component.replace(reservedCharacterPattern, replaceWildcardCharacter);
+                }
             }
 
             hasWrittenComponent = true;
@@ -1988,14 +2035,6 @@ namespace ts {
         return subpattern;
     }
 
-    function replaceWildCardCharacterFiles(match: string) {
-        return replaceWildcardCharacter(match, singleAsteriskRegexFragmentFiles);
-    }
-
-    function replaceWildCardCharacterOther(match: string) {
-        return replaceWildcardCharacter(match, singleAsteriskRegexFragmentOther);
-    }
-
     function replaceWildcardCharacter(match: string, singleAsteriskRegexFragment: string) {
         return match === "*" ? singleAsteriskRegexFragment : match === "?" ? "[^/]" : "\\" + match;
     }
@@ -2350,15 +2389,40 @@ namespace ts {
             return currentAssertionLevel >= level;
         }
 
-        export function assert(expression: boolean, message?: string, verboseDebugInfo?: () => string, stackCrawlMark?: Function): void {
+        export function assert(expression: boolean, message?: string, verboseDebugInfo?: string | (() => string), stackCrawlMark?: Function): void {
             if (!expression) {
                 if (verboseDebugInfo) {
-                    message += "\r\nVerbose Debug Information: " + verboseDebugInfo();
+                    message += "\r\nVerbose Debug Information: " + (typeof verboseDebugInfo === "string" ? verboseDebugInfo : verboseDebugInfo());
                 }
                 fail(message ? "False expression: " + message : "False expression.", stackCrawlMark || assert);
             }
         }
 
+        export function assertEqual<T>(a: T, b: T, msg?: string, msg2?: string): void {
+            if (a !== b) {
+                const message = msg ? msg2 ? `${msg} ${msg2}` : msg : "";
+                fail(`Expected ${a} === ${b}. ${message}`);
+            }
+        }
+
+        export function assertLessThan(a: number, b: number, msg?: string): void {
+            if (a >= b) {
+                fail(`Expected ${a} < ${b}. ${msg || ""}`);
+            }
+        }
+
+        export function assertLessThanOrEqual(a: number, b: number): void {
+            if (a > b) {
+                fail(`Expected ${a} <= ${b}`);
+            }
+        }
+
+        export function assertGreaterThanOrEqual(a: number, b: number): void {
+            if (a < b) {
+                fail(`Expected ${a} >= ${b}`);
+            }
+        }
+
         export function fail(message?: string, stackCrawlMark?: Function): void {
             debugger;
             const e = new Error(message ? `Debug Failure. ${message}` : "Debug Failure.");
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 3b4b0ddf667..03164c54ffd 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1908,6 +1908,10 @@
         "category": "Error",
         "code": 2559
     },
+    "Value of type '{0}' has no properties in common with type '{1}'. Did you mean to call it?": {
+        "category": "Error",
+        "code": 2560
+    },
     "JSX element attributes type '{0}' may not be a union type.": {
         "category": "Error",
         "code": 2600
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 4f07331a98e..923e6da4215 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -1572,8 +1572,20 @@ namespace ts {
             write(";");
         }
 
+        function emitTokenWithComment(token: SyntaxKind, pos: number, contextNode?: Node) {
+            const node = contextNode && getParseTreeNode(contextNode);
+            if (node && node.kind === contextNode.kind) {
+                pos = skipTrivia(currentSourceFile.text, pos);
+            }
+            pos = writeToken(token, pos, /*contextNode*/ contextNode);
+            if (node && node.kind === contextNode.kind) {
+                emitTrailingCommentsOfPosition(pos, /*prefixSpace*/ true);
+            }
+            return pos;
+        }
+
         function emitReturnStatement(node: ReturnStatement) {
-            writeToken(SyntaxKind.ReturnKeyword, node.pos, /*contextNode*/ node);
+            emitTokenWithComment(SyntaxKind.ReturnKeyword, node.pos, /*contextNode*/ node);
             emitExpressionWithPrefix(" ", node.expression);
             write(";");
         }
@@ -2133,10 +2145,12 @@ namespace ts {
         function emitCatchClause(node: CatchClause) {
             const openParenPos = writeToken(SyntaxKind.CatchKeyword, node.pos);
             write(" ");
-            writeToken(SyntaxKind.OpenParenToken, openParenPos);
-            emit(node.variableDeclaration);
-            writeToken(SyntaxKind.CloseParenToken, node.variableDeclaration ? node.variableDeclaration.end : openParenPos);
-            write(" ");
+            if (node.variableDeclaration) {
+                writeToken(SyntaxKind.OpenParenToken, openParenPos);
+                emit(node.variableDeclaration);
+                writeToken(SyntaxKind.CloseParenToken, node.variableDeclaration.end);
+                write(" ");
+            }
             emit(node.block);
         }
 
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 34727e4c414..47df0a9bdc2 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -2128,14 +2128,14 @@ namespace ts {
             : node;
     }
 
-    export function createCatchClause(variableDeclaration: string | VariableDeclaration, block: Block) {
+    export function createCatchClause(variableDeclaration: string | VariableDeclaration | undefined, block: Block) {
         const node = <CatchClause>createSynthesizedNode(SyntaxKind.CatchClause);
         node.variableDeclaration = typeof variableDeclaration === "string" ? createVariableDeclaration(variableDeclaration) : variableDeclaration;
         node.block = block;
         return node;
     }
 
-    export function updateCatchClause(node: CatchClause, variableDeclaration: VariableDeclaration, block: Block) {
+    export function updateCatchClause(node: CatchClause, variableDeclaration: VariableDeclaration | undefined, block: Block) {
         return node.variableDeclaration !== variableDeclaration
             || node.block !== block
             ? updateNode(createCatchClause(variableDeclaration, block), node)
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 513c741ba09..be867db9743 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -678,7 +678,7 @@ namespace ts {
         const { resolvedModule, failedLookupLocations } =
             nodeModuleNameResolverWorker(moduleName, initialDir, { moduleResolution: ts.ModuleResolutionKind.NodeJs, allowJs: true }, host, /*cache*/ undefined, /*jsOnly*/ true);
         if (!resolvedModule) {
-            throw new Error(`Could not resolve JS module ${moduleName} starting at ${initialDir}. Looked in: ${failedLookupLocations.join(", ")}`);
+            throw new Error(`Could not resolve JS module '${moduleName}' starting at '${initialDir}'. Looked in: ${failedLookupLocations.join(", ")}`);
         }
         return resolvedModule.resolvedFileName;
     }
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 49b682c7302..ee47771d619 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -4799,11 +4799,16 @@ namespace ts {
         function parseCatchClause(): CatchClause {
             const result = <CatchClause>createNode(SyntaxKind.CatchClause);
             parseExpected(SyntaxKind.CatchKeyword);
-            if (parseExpected(SyntaxKind.OpenParenToken)) {
+
+            if (parseOptional(SyntaxKind.OpenParenToken)) {
                 result.variableDeclaration = parseVariableDeclaration();
+                parseExpected(SyntaxKind.CloseParenToken);
+            }
+            else {
+                // Keep shape of node to avoid degrading performance.
+                result.variableDeclaration = undefined;
             }
 
-            parseExpected(SyntaxKind.CloseParenToken);
             result.block = parseBlock(/*ignoreMissingOpenBrace*/ false);
             return finishNode(result);
         }
diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 89cfb074bff..8a4c4ad22cc 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -153,7 +153,7 @@ namespace ts {
                         return;
                     }
                     watcher = _fs.watch(
-                        dirPath,
+                        dirPath || ".",
                         { persistent: true },
                         (eventName: string, relativeFileName: string) => fileEventHandler(eventName, relativeFileName, dirPath)
                     );
diff --git a/src/compiler/transformers/es2015.ts b/src/compiler/transformers/es2015.ts
index f97de018d4a..2b0b175e2a5 100644
--- a/src/compiler/transformers/es2015.ts
+++ b/src/compiler/transformers/es2015.ts
@@ -2491,7 +2491,7 @@ namespace ts {
             const catchVariable = getGeneratedNameForNode(errorRecord);
             const returnMethod = createTempVariable(/*recordTempVariable*/ undefined);
             const values = createValuesHelper(context, expression, node.expression);
-            const next = createCall(createPropertyAccess(iterator, "next" ), /*typeArguments*/ undefined, []);
+            const next = createCall(createPropertyAccess(iterator, "next"), /*typeArguments*/ undefined, []);
 
             hoistVariableDeclaration(errorRecord);
             hoistVariableDeclaration(returnMethod);
@@ -3173,6 +3173,7 @@ namespace ts {
         function visitCatchClause(node: CatchClause): CatchClause {
             const ancestorFacts = enterSubtree(HierarchyFacts.BlockScopeExcludes, HierarchyFacts.BlockScopeIncludes);
             let updated: CatchClause;
+            Debug.assert(!!node.variableDeclaration, "Catch clause variable should always be present when downleveling ES2015.");
             if (isBindingPattern(node.variableDeclaration.name)) {
                 const temp = createTempVariable(/*recordTempVariable*/ undefined);
                 const newVariableDeclaration = createVariableDeclaration(temp);
diff --git a/src/compiler/transformers/esnext.ts b/src/compiler/transformers/esnext.ts
index 3d884001932..8d71016b051 100644
--- a/src/compiler/transformers/esnext.ts
+++ b/src/compiler/transformers/esnext.ts
@@ -101,6 +101,8 @@ namespace ts {
                     return visitExpressionStatement(node as ExpressionStatement);
                 case SyntaxKind.ParenthesizedExpression:
                     return visitParenthesizedExpression(node as ParenthesizedExpression, noDestructuringValue);
+                case SyntaxKind.CatchClause:
+                    return visitCatchClause(node as CatchClause);
                 default:
                     return visitEachChild(node, visitor, context);
             }
@@ -212,6 +214,17 @@ namespace ts {
             return visitEachChild(node, noDestructuringValue ? visitorNoDestructuringValue : visitor, context);
         }
 
+        function visitCatchClause(node: CatchClause): CatchClause {
+            if (!node.variableDeclaration) {
+                return updateCatchClause(
+                    node,
+                    createVariableDeclaration(createTempVariable(/*recordTempVariable*/ undefined)),
+                    visitNode(node.block, visitor, isBlock)
+                );
+            }
+            return visitEachChild(node, visitor, context);
+        }
+
         /**
          * Visits a BinaryExpression that contains a destructuring assignment.
          *
diff --git a/src/compiler/transformers/generators.ts b/src/compiler/transformers/generators.ts
index 41edf24fe9e..5e2016ab590 100644
--- a/src/compiler/transformers/generators.ts
+++ b/src/compiler/transformers/generators.ts
@@ -2448,7 +2448,7 @@ namespace ts {
          * @param location An optional source map location for the statement.
          */
         function createInlineBreak(label: Label, location?: TextRange): ReturnStatement {
-            Debug.assert(label > 0, `Invalid label: ${label}`);
+            Debug.assertLessThan(0, label, "Invalid label");
             return setTextRange(
                 createReturn(
                     createArrayLiteral([
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 3b57608abc5..27dcbda309f 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -1808,7 +1808,7 @@ namespace ts {
     export interface CatchClause extends Node {
         kind: SyntaxKind.CatchClause;
         parent?: TryStatement;
-        variableDeclaration: VariableDeclaration;
+        variableDeclaration?: VariableDeclaration;
         block: Block;
     }
 
@@ -3067,6 +3067,7 @@ namespace ts {
         hasReportedStatementInAmbientContext?: boolean;  // Cache boolean if we report statements in ambient context
         jsxFlags?: JsxFlags;              // flags for knowing what kind of element/attributes we're dealing with
         resolvedJsxElementAttributesType?: Type;  // resolved element attributes type of a JSX openinglike element
+        resolvedJsxElementAllAttributesType?: Type;  // resolved all element attributes type of a JSX openinglike element
         hasSuperCall?: boolean;           // recorded result when we try to find super-call. We only try to find one if this flag is undefined, indicating that we haven't made an attempt.
         superCall?: ExpressionStatement;  // Cached first super-call found in the constructor. Used in checking whether super is called before this-accessing
         switchTypes?: Type[];             // Cached array of switch case expression types
@@ -3317,6 +3318,11 @@ namespace ts {
         awaitedTypeOfType?: Type;
     }
 
+    /* @internal */
+    export interface SyntheticDefaultModuleType extends Type {
+        syntheticType?: Type;
+    }
+
     export interface TypeVariable extends Type {
         /* @internal */
         resolvedBaseConstraint: Type;
@@ -4019,7 +4025,6 @@ namespace ts {
         ContainsBindingPattern = 1 << 23,
         ContainsYield = 1 << 24,
         ContainsHoistedDeclarationOrCompletion = 1 << 25,
-
         ContainsDynamicImport = 1 << 26,
 
         // Please leave this as 1 << 29.
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 55a8f3ebb4d..7122f55cae2 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -420,7 +420,7 @@ namespace Utils {
 
     const maxHarnessFrames = 1;
 
-    export function filterStack(error: Error, stackTraceLimit: number = Infinity) {
+    export function filterStack(error: Error, stackTraceLimit = Infinity) {
         const stack = <string>(<any>error).stack;
         if (stack) {
             const lines = stack.split(/\r\n?|\n/g);
diff --git a/src/harness/harnessLanguageService.ts b/src/harness/harnessLanguageService.ts
index 3cb65613a2d..7a7636b5ff5 100644
--- a/src/harness/harnessLanguageService.ts
+++ b/src/harness/harnessLanguageService.ts
@@ -684,11 +684,11 @@ namespace Harness.LanguageService {
         }
 
         info(message: string): void {
-            return this.host.log(message);
+            this.host.log(message);
         }
 
-        msg(message: string) {
-            return this.host.log(message);
+        err(message: string): void {
+            this.host.log(message);
         }
 
         loggingEnabled() {
@@ -703,17 +703,12 @@ namespace Harness.LanguageService {
             return false;
         }
 
-
-        endGroup(): void {
-        }
+        group() { throw ts.notImplemented(); }
 
         perftrc(message: string): void {
             return this.host.log(message);
         }
 
-        startGroup(): void {
-        }
-
         setTimeout(callback: (...args: any[]) => void, ms: number, ...args: any[]): any {
             return setTimeout(callback, ms, args);
         }
@@ -798,7 +793,7 @@ namespace Harness.LanguageService {
                 default:
                     return {
                         module: undefined,
-                        error: "Could not resolve module"
+                        error: new Error("Could not resolve module")
                     };
             }
 
diff --git a/src/harness/unittests/cachingInServerLSHost.ts b/src/harness/unittests/cachingInServerLSHost.ts
index eb2907e89de..92c10c1ff6d 100644
--- a/src/harness/unittests/cachingInServerLSHost.ts
+++ b/src/harness/unittests/cachingInServerLSHost.ts
@@ -52,21 +52,9 @@ namespace ts {
     }
 
     function createProject(rootFile: string, serverHost: server.ServerHost): { project: server.Project, rootScriptInfo: server.ScriptInfo } {
-        const logger: server.Logger = {
-            close: noop,
-            hasLevel: () => false,
-            loggingEnabled: () => false,
-            perftrc: noop,
-            info: noop,
-            startGroup: noop,
-            endGroup: noop,
-            msg: noop,
-            getLogFileName: (): string => undefined
-        };
-
         const svcOpts: server.ProjectServiceOptions = {
             host: serverHost,
-            logger,
+            logger: projectSystem.nullLogger,
             cancellationToken: { isCancellationRequested: () => false },
             useSingleInferredProject: false,
             typingsInstaller: undefined
diff --git a/src/harness/unittests/matchFiles.ts b/src/harness/unittests/matchFiles.ts
index e0454671930..9e2a5883754 100644
--- a/src/harness/unittests/matchFiles.ts
+++ b/src/harness/unittests/matchFiles.ts
@@ -73,6 +73,7 @@ namespace ts {
         "c:/dev/a.d.ts",
         "c:/dev/a.js",
         "c:/dev/b.ts",
+        "c:/dev/x/a.ts",
         "c:/dev/node_modules/a.ts",
         "c:/dev/bower_components/a.ts",
         "c:/dev/jspm_packages/a.ts"
@@ -141,7 +142,8 @@ namespace ts {
                 errors: [],
                 fileNames: [
                     "c:/dev/a.ts",
-                    "c:/dev/b.ts"
+                    "c:/dev/b.ts",
+                    "c:/dev/x/a.ts"
                 ],
                 wildcardDirectories: {
                     "c:/dev": ts.WatchDirectoryFlags.Recursive
@@ -462,7 +464,6 @@ namespace ts {
                 };
                 validateMatches(expected, json, caseInsensitiveHost, caseInsensitiveBasePath);
             });
-
             it("same named declarations are excluded", () => {
                 const json = {
                     include: [
@@ -651,71 +652,127 @@ namespace ts {
                 };
                 validateMatches(expected, json, caseInsensitiveHost, caseInsensitiveBasePath);
             });
-            it("with common package folders and no exclusions", () => {
-                const json = {
-                    include: [
-                        "**/a.ts"
-                    ]
-                };
-                const expected: ts.ParsedCommandLine = {
-                    options: {},
-                    errors: [],
-                    fileNames: [
-                        "c:/dev/a.ts",
-                        "c:/dev/bower_components/a.ts",
-                        "c:/dev/jspm_packages/a.ts",
-                        "c:/dev/node_modules/a.ts"
-                    ],
-                    wildcardDirectories: {
-                        "c:/dev": ts.WatchDirectoryFlags.Recursive
-                    },
-                };
-                validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-            });
-            it("with common package folders and exclusions", () => {
-                const json = {
-                    include: [
-                        "**/a.ts"
-                    ],
-                    exclude: [
-                        "a.ts"
-                    ]
-                };
-                const expected: ts.ParsedCommandLine = {
-                    options: {},
-                    errors: [],
-                    fileNames: [
-                        "c:/dev/bower_components/a.ts",
-                        "c:/dev/jspm_packages/a.ts",
-                        "c:/dev/node_modules/a.ts"
-                    ],
-                    wildcardDirectories: {
-                        "c:/dev": ts.WatchDirectoryFlags.Recursive
-                    },
-                };
-                validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
-            });
-            it("with common package folders and empty exclude", () => {
-                const json = {
-                    include: [
-                        "**/a.ts"
-                    ],
-                    exclude: <string[]>[]
-                };
-                const expected: ts.ParsedCommandLine = {
-                    options: {},
-                    errors: [],
-                    fileNames: [
-                        "c:/dev/a.ts",
-                        "c:/dev/bower_components/a.ts",
-                        "c:/dev/jspm_packages/a.ts",
-                        "c:/dev/node_modules/a.ts"
-                    ],
-                    wildcardDirectories: {
-                        "c:/dev": ts.WatchDirectoryFlags.Recursive
-                    },
-                };
-                validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+            describe("with common package folders", () => {
+                it("and no exclusions", () => {
+                    const json = {
+                        include: [
+                            "**/a.ts"
+                        ]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/a.ts",
+                            "c:/dev/x/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
+                it("and exclusions", () => {
+                    const json = {
+                        include: [
+                            "**/?.ts"
+                        ],
+                        exclude: [
+                            "a.ts"
+                        ]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/b.ts",
+                            "c:/dev/x/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
+                it("and empty exclude", () => {
+                    const json = {
+                        include: [
+                            "**/a.ts"
+                        ],
+                        exclude: <string[]>[]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/a.ts",
+                            "c:/dev/x/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
+                it("and explicit recursive include", () => {
+                    const json = {
+                        include: [
+                            "**/a.ts",
+                            "**/node_modules/a.ts"
+                        ]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/a.ts",
+                            "c:/dev/x/a.ts",
+                            "c:/dev/node_modules/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
+                it("and wildcard include", () => {
+                    const json = {
+                        include: [
+                            "*/a.ts"
+                        ]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/x/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
+                it("and explicit wildcard include", () => {
+                    const json = {
+                        include: [
+                            "*/a.ts",
+                            "node_modules/a.ts"
+                        ]
+                    };
+                    const expected: ts.ParsedCommandLine = {
+                        options: {},
+                        errors: [],
+                        fileNames: [
+                            "c:/dev/x/a.ts",
+                            "c:/dev/node_modules/a.ts"
+                        ],
+                        wildcardDirectories: {
+                            "c:/dev": ts.WatchDirectoryFlags.Recursive
+                        },
+                    };
+                    validateMatches(expected, json, caseInsensitiveCommonFoldersHost, caseInsensitiveBasePath);
+                });
             });
             it("exclude .js files when allowJs=false", () => {
                 const json = {
@@ -1066,6 +1123,7 @@ namespace ts {
                 };
                 validateMatches(expected, json, caseInsensitiveHost, caseInsensitiveBasePath);
             });
+
             describe("with trailing recursive directory", () => {
                 it("in includes", () => {
                     const json = {
@@ -1264,6 +1322,7 @@ namespace ts {
                 });
             });
         });
+
         describe("with files or folders that begin with a .", () => {
             it("that are not explicitly included", () => {
                 const json = {
diff --git a/src/harness/unittests/session.ts b/src/harness/unittests/session.ts
index 862ebee4b03..1ce5792a81b 100644
--- a/src/harness/unittests/session.ts
+++ b/src/harness/unittests/session.ts
@@ -28,18 +28,6 @@ namespace ts.server {
         createHash: Harness.LanguageService.mockHash,
     };
 
-    const mockLogger: Logger = {
-        close: noop,
-        hasLevel(): boolean { return false; },
-        loggingEnabled(): boolean { return false; },
-        perftrc: noop,
-        info: noop,
-        startGroup: noop,
-        endGroup: noop,
-        msg: noop,
-        getLogFileName: (): string => undefined
-    };
-
     class TestSession extends Session {
         getProjectService() {
             return this.projectService;
@@ -58,7 +46,7 @@ namespace ts.server {
                 typingsInstaller: undefined,
                 byteLength: Utils.byteLength,
                 hrtime: process.hrtime,
-                logger: mockLogger,
+                logger: projectSystem.nullLogger,
                 canUseEvents: true
             };
             return new TestSession(opts);
@@ -408,7 +396,7 @@ namespace ts.server {
                     typingsInstaller: undefined,
                     byteLength: Utils.byteLength,
                     hrtime: process.hrtime,
-                    logger: mockLogger,
+                    logger: projectSystem.nullLogger,
                     canUseEvents: true
                 });
                 this.addProtocolHandler(this.customHandler, () => {
@@ -475,7 +463,7 @@ namespace ts.server {
                     typingsInstaller: undefined,
                     byteLength: Utils.byteLength,
                     hrtime: process.hrtime,
-                    logger: mockLogger,
+                    logger: projectSystem.nullLogger,
                     canUseEvents: true
                 });
                 this.addProtocolHandler("echo", (req: protocol.Request) => ({
diff --git a/src/harness/unittests/tsserverProjectSystem.ts b/src/harness/unittests/tsserverProjectSystem.ts
index 4a7cafa245b..6c60160740e 100644
--- a/src/harness/unittests/tsserverProjectSystem.ts
+++ b/src/harness/unittests/tsserverProjectSystem.ts
@@ -34,18 +34,17 @@ namespace ts.projectSystem {
     }
 
     export const nullLogger: server.Logger = {
-        close: () => void 0,
-        hasLevel: () => void 0,
+        close: noop,
+        hasLevel: () => false,
         loggingEnabled: () => false,
-        perftrc: () => void 0,
-        info: () => void 0,
-        startGroup: () => void 0,
-        endGroup: () => void 0,
-        msg: () => void 0,
+        perftrc: noop,
+        info: noop,
+        err: noop,
+        group: noop,
         getLogFileName: (): string => undefined
     };
 
-    export const { content: libFileContent } = Harness.getDefaultLibraryFile(Harness.IO);
+    const { content: libFileContent } = Harness.getDefaultLibraryFile(Harness.IO);
     export const libFile: FileOrFolder = {
         path: "/a/lib/lib.d.ts",
         content: libFileContent
@@ -118,7 +117,7 @@ namespace ts.projectSystem {
         return JSON.stringify({ dependencies });
     }
 
-    export function getExecutingFilePathFromLibFile(): string {
+    function getExecutingFilePathFromLibFile(): string {
         return combinePaths(getDirectoryPath(libFile.path), "tsc.js");
     }
 
@@ -130,7 +129,7 @@ namespace ts.projectSystem {
         return map(fileNames, toExternalFile);
     }
 
-    export class TestServerEventManager {
+    class TestServerEventManager {
         public events: server.ProjectServiceEvent[] = [];
 
         handler: server.ProjectServiceEventHandler = (event: server.ProjectServiceEvent) => {
@@ -143,7 +142,7 @@ namespace ts.projectSystem {
         }
     }
 
-    export interface TestServerHostCreationParameters {
+    interface TestServerHostCreationParameters {
         useCaseSensitiveFileNames?: boolean;
         executingFilePath?: string;
         currentDirectory?: string;
@@ -205,7 +204,7 @@ namespace ts.projectSystem {
         return new TestSession(opts);
     }
 
-    export interface CreateProjectServiceParameters {
+    interface CreateProjectServiceParameters {
         cancellationToken?: HostCancellationToken;
         logger?: server.Logger;
         useSingleInferredProject?: boolean;
@@ -253,15 +252,15 @@ namespace ts.projectSystem {
         entries: FSEntry[];
     }
 
-    export function isFolder(s: FSEntry): s is Folder {
+    function isFolder(s: FSEntry): s is Folder {
         return isArray((<Folder>s).entries);
     }
 
-    export function isFile(s: FSEntry): s is File {
+    function isFile(s: FSEntry): s is File {
         return typeof (<File>s).content === "string";
     }
 
-    export function addFolder(fullPath: string, toPath: (s: string) => Path, fs: Map<FSEntry>): Folder {
+    function addFolder(fullPath: string, toPath: (s: string) => Path, fs: Map<FSEntry>): Folder {
         const path = toPath(fullPath);
         if (fs.has(path)) {
             Debug.assert(isFolder(fs.get(path)));
@@ -279,29 +278,29 @@ namespace ts.projectSystem {
         return entry;
     }
 
-    export function checkMapKeys(caption: string, map: Map<any>, expectedKeys: string[]) {
+    function checkMapKeys(caption: string, map: Map<any>, expectedKeys: string[]) {
         assert.equal(map.size, expectedKeys.length, `${caption}: incorrect size of map`);
         for (const name of expectedKeys) {
             assert.isTrue(map.has(name), `${caption} is expected to contain ${name}, actual keys: ${arrayFrom(map.keys())}`);
         }
     }
 
-    export function checkFileNames(caption: string, actualFileNames: string[], expectedFileNames: string[]) {
+    function checkFileNames(caption: string, actualFileNames: string[], expectedFileNames: string[]) {
         assert.equal(actualFileNames.length, expectedFileNames.length, `${caption}: incorrect actual number of files, expected ${JSON.stringify(expectedFileNames)}, got ${actualFileNames}`);
         for (const f of expectedFileNames) {
             assert.isTrue(contains(actualFileNames, f), `${caption}: expected to find ${f} in ${JSON.stringify(actualFileNames)}`);
         }
     }
 
-    export function checkNumberOfConfiguredProjects(projectService: server.ProjectService, expected: number) {
+    function checkNumberOfConfiguredProjects(projectService: server.ProjectService, expected: number) {
         assert.equal(projectService.configuredProjects.length, expected, `expected ${expected} configured project(s)`);
     }
 
-    export function checkNumberOfExternalProjects(projectService: server.ProjectService, expected: number) {
+    function checkNumberOfExternalProjects(projectService: server.ProjectService, expected: number) {
         assert.equal(projectService.externalProjects.length, expected, `expected ${expected} external project(s)`);
     }
 
-    export function checkNumberOfInferredProjects(projectService: server.ProjectService, expected: number) {
+    function checkNumberOfInferredProjects(projectService: server.ProjectService, expected: number) {
         assert.equal(projectService.inferredProjects.length, expected, `expected ${expected} inferred project(s)`);
     }
 
@@ -315,7 +314,7 @@ namespace ts.projectSystem {
         checkMapKeys("watchedFiles", host.watchedFiles, expectedFiles);
     }
 
-    export function checkWatchedDirectories(host: TestServerHost, expectedDirectories: string[]) {
+    function checkWatchedDirectories(host: TestServerHost, expectedDirectories: string[]) {
         checkMapKeys("watchedDirectories", host.watchedDirectories, expectedDirectories);
     }
 
@@ -323,11 +322,11 @@ namespace ts.projectSystem {
         checkFileNames(`${server.ProjectKind[project.projectKind]} project, actual files`, project.getFileNames(), expectedFiles);
     }
 
-    export function checkProjectRootFiles(project: server.Project, expectedFiles: string[]) {
+    function checkProjectRootFiles(project: server.Project, expectedFiles: string[]) {
         checkFileNames(`${server.ProjectKind[project.projectKind]} project, rootFileNames`, project.getRootFiles(), expectedFiles);
     }
 
-    export class Callbacks {
+    class Callbacks {
         private map: TimeOutCallback[] = [];
         private nextId = 1;
 
@@ -363,7 +362,7 @@ namespace ts.projectSystem {
         }
     }
 
-    export type TimeOutCallback = () => any;
+    type TimeOutCallback = () => any;
 
     export class TestServerHost implements server.ServerHost {
         args: string[] = [];
diff --git a/src/lib/es2015.symbol.wellknown.d.ts b/src/lib/es2015.symbol.wellknown.d.ts
index 578cf0acbc2..b7c2610e652 100644
--- a/src/lib/es2015.symbol.wellknown.d.ts
+++ b/src/lib/es2015.symbol.wellknown.d.ts
@@ -110,7 +110,7 @@ interface Map<K, V> {
     readonly [Symbol.toStringTag]: "Map";
 }
 
-interface WeakMap<K extends object, V>{
+interface WeakMap<K extends object, V> {
     readonly [Symbol.toStringTag]: "WeakMap";
 }
 
diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 4ffdf5d6c5d..554ac337920 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -326,8 +326,8 @@ namespace ts.server {
         typingsInstaller: ITypingsInstaller;
         eventHandler?: ProjectServiceEventHandler;
         throttleWaitMilliseconds?: number;
-        globalPlugins?: string[];
-        pluginProbeLocations?: string[];
+        globalPlugins?: ReadonlyArray<string>;
+        pluginProbeLocations?: ReadonlyArray<string>;
         allowLocalPluginLoads?: boolean;
     }
 
@@ -928,26 +928,24 @@ namespace ts.server {
                 return;
             }
 
-            this.logger.startGroup();
+            this.logger.group(info => {
+                let counter = 0;
+                counter = printProjects(this.externalProjects, info, counter);
+                counter = printProjects(this.configuredProjects, info, counter);
+                printProjects(this.inferredProjects, info, counter);
 
-            let counter = 0;
-            counter = printProjects(this.logger, this.externalProjects, counter);
-            counter = printProjects(this.logger, this.configuredProjects, counter);
-            counter = printProjects(this.logger, this.inferredProjects, counter);
+                info("Open files: ");
+                for (const rootFile of this.openFiles) {
+                    info(`\t${rootFile.fileName}`);
+                }
+            });
 
-            this.logger.info("Open files: ");
-            for (const rootFile of this.openFiles) {
-                this.logger.info(`\t${rootFile.fileName}`);
-            }
-
-            this.logger.endGroup();
-
-            function printProjects(logger: Logger, projects: Project[], counter: number) {
+            function printProjects(projects: Project[], info: (msg: string) => void, counter: number): number {
                 for (const project of projects) {
                     project.updateGraph();
-                    logger.info(`Project '${project.getProjectName()}' (${ProjectKind[project.projectKind]}) ${counter}`);
-                    logger.info(project.filesToString());
-                    logger.info("-----------------------------------------------");
+                    info(`Project '${project.getProjectName()}' (${ProjectKind[project.projectKind]}) ${counter}`);
+                    info(project.filesToString());
+                    info("-----------------------------------------------");
                     counter++;
                 }
                 return counter;
diff --git a/src/server/project.ts b/src/server/project.ts
index 524b6c4d28d..97c8eb706f3 100644
--- a/src/server/project.ts
+++ b/src/server/project.ts
@@ -170,7 +170,8 @@ namespace ts.server {
             log(`Loading ${moduleName} from ${initialDir} (resolved to ${resolvedPath})`);
             const result = host.require(resolvedPath, moduleName);
             if (result.error) {
-                log(`Failed to load module: ${JSON.stringify(result.error)}`);
+                const err = result.error.stack || result.error.message || JSON.stringify(result.error);
+                log(`Failed to load module '${moduleName}': ${err}`);
                 return undefined;
             }
             return result.module;
@@ -362,7 +363,7 @@ namespace ts.server {
             return map(this.program.getSourceFiles(), sourceFile => {
                 const scriptInfo = this.projectService.getScriptInfoForPath(sourceFile.path);
                 if (!scriptInfo) {
-                    Debug.assert(false, `scriptInfo for a file '${sourceFile.fileName}' is missing.`);
+                    Debug.fail(`scriptInfo for a file '${sourceFile.fileName}' is missing.`);
                 }
                 return scriptInfo;
             });
@@ -494,7 +495,7 @@ namespace ts.server {
             this.projectStateVersion++;
         }
 
-        private extractUnresolvedImportsFromSourceFile(file: SourceFile, result: string[]) {
+        private extractUnresolvedImportsFromSourceFile(file: SourceFile, result: Push<string>) {
             const cached = this.cachedUnresolvedImportsPerFile.get(file.path);
             if (cached) {
                 // found cached result - use it and return
@@ -554,7 +555,7 @@ namespace ts.server {
                 for (const sourceFile of this.program.getSourceFiles()) {
                     this.extractUnresolvedImportsFromSourceFile(sourceFile, result);
                 }
-                this.lastCachedUnresolvedImportsList = toSortedArray(result);
+                this.lastCachedUnresolvedImportsList = toDeduplicatedSortedArray(result);
             }
             unresolvedImports = this.lastCachedUnresolvedImportsList;
 
diff --git a/src/server/server.ts b/src/server/server.ts
index b72cc2f5a81..47a858c0efd 100644
--- a/src/server/server.ts
+++ b/src/server/server.ts
@@ -15,8 +15,8 @@ namespace ts.server {
         typingSafeListLocation: string;
         npmLocation: string | undefined;
         telemetryEnabled: boolean;
-        globalPlugins: string[];
-        pluginProbeLocations: string[];
+        globalPlugins: ReadonlyArray<string>;
+        pluginProbeLocations: ReadonlyArray<string>;
         allowLocalPluginLoads: boolean;
     }
 
@@ -116,8 +116,6 @@ namespace ts.server {
         birthtime: Date;
     }
 
-    type RequireResult = { module: {}, error: undefined } | { module: undefined, error: {} };
-
     const readline: {
         createInterface(options: ReadLineOptions): NodeJS.EventEmitter;
     } = require("readline");
@@ -141,8 +139,6 @@ namespace ts.server {
     class Logger implements server.Logger {
         private fd = -1;
         private seq = 0;
-        private inGroup = false;
-        private firstInGroup = true;
 
         constructor(private readonly logFilename: string,
             private readonly traceToConsole: boolean,
@@ -172,22 +168,24 @@ namespace ts.server {
         }
 
         perftrc(s: string) {
-            this.msg(s, Msg.Perf);
+            this.msg(s, "Perf");
         }
 
         info(s: string) {
-            this.msg(s, Msg.Info);
+            this.msg(s, "Info");
         }
 
-        startGroup() {
-            this.inGroup = true;
-            this.firstInGroup = true;
+        err(s: string) {
+            this.msg(s, "Err");
         }
 
-        endGroup() {
-            this.inGroup = false;
+        group(logGroupEntries: (log: (msg: string) => void) => void) {
+            let firstInGroup = false;
+            logGroupEntries(s => {
+                this.msg(s, "Info", /*inGroup*/ true, firstInGroup);
+                firstInGroup = false;
+            });
             this.seq++;
-            this.firstInGroup = true;
         }
 
         loggingEnabled() {
@@ -198,26 +196,32 @@ namespace ts.server {
             return this.loggingEnabled() && this.level >= level;
         }
 
-        msg(s: string, type: Msg.Types = Msg.Err) {
-            if (this.fd >= 0 || this.traceToConsole) {
-                s = `[${nowString()}] ${s}\n`;
+        private msg(s: string, type: string, inGroup = false, firstInGroup = false) {
+            if (!this.canWrite) return;
+
+            s = `[${nowString()}] ${s}\n`;
+            if (!inGroup || firstInGroup) {
                 const prefix = Logger.padStringRight(type + " " + this.seq.toString(), "          ");
-                if (this.firstInGroup) {
-                    s = prefix + s;
-                    this.firstInGroup = false;
-                }
-                if (!this.inGroup) {
-                    this.seq++;
-                    this.firstInGroup = true;
-                }
-                if (this.fd >= 0) {
-                    const buf = new Buffer(s);
-                    // tslint:disable-next-line no-null-keyword
-                    fs.writeSync(this.fd, buf, 0, buf.length, /*position*/ null);
-                }
-                if (this.traceToConsole) {
-                    console.warn(s);
-                }
+                s = prefix + s;
+            }
+            this.write(s);
+            if (!inGroup) {
+                this.seq++;
+            }
+        }
+
+        private get canWrite() {
+            return this.fd >= 0 || this.traceToConsole;
+        }
+
+        private write(s: string) {
+            if (this.fd >= 0) {
+                const buf = new Buffer(s);
+                // tslint:disable-next-line no-null-keyword
+                fs.writeSync(this.fd, buf, 0, buf.length, /*position*/ null);
+            }
+            if (this.traceToConsole) {
+                console.warn(s);
             }
         }
     }
@@ -762,8 +766,16 @@ namespace ts.server {
     const typingSafeListLocation = findArgument(Arguments.TypingSafeListLocation);
     const npmLocation = findArgument(Arguments.NpmLocation);
 
-    const globalPlugins = (findArgument("--globalPlugins") || "").split(",");
-    const pluginProbeLocations = (findArgument("--pluginProbeLocations") || "").split(",");
+    function parseStringArray(argName: string): ReadonlyArray<string> {
+        const arg = findArgument(argName);
+        if (arg === undefined) {
+            return emptyArray;
+        }
+        return arg.split(",").filter(name => name !== "");
+    }
+
+    const globalPlugins = parseStringArray("--globalPlugins");
+    const pluginProbeLocations = parseStringArray("--pluginProbeLocations");
     const allowLocalPluginLoads = hasArgument("--allowLocalPluginLoads");
 
     const useSingleInferredProject = hasArgument("--useSingleInferredProject");
diff --git a/src/server/session.ts b/src/server/session.ts
index d297b45bbb1..ddadf51e095 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -163,26 +163,22 @@ namespace ts.server {
      * Scheduling is done via instance of NextStep. If on current step subsequent step was not scheduled - operation is assumed to be completed.
      */
     class MultistepOperation implements NextStep {
-        private requestId: number;
+        private requestId: number | undefined;
         private timerHandle: any;
-        private immediateId: any;
-        private completed = true;
+        private immediateId: number | undefined;
 
         constructor(private readonly operationHost: MultistepOperationHost) {}
 
         public startNew(action: (next: NextStep) => void) {
             this.complete();
             this.requestId = this.operationHost.getCurrentRequestId();
-            this.completed = false;
             this.executeAction(action);
         }
 
         private complete() {
-            if (!this.completed) {
-                if (this.requestId) {
-                    this.operationHost.sendRequestCompletedEvent(this.requestId);
-                }
-                this.completed = true;
+            if (this.requestId !== undefined) {
+                this.operationHost.sendRequestCompletedEvent(this.requestId);
+                this.requestId = undefined;
             }
             this.setTimerHandle(undefined);
             this.setImmediateId(undefined);
@@ -259,8 +255,8 @@ namespace ts.server {
         eventHandler?: ProjectServiceEventHandler;
         throttleWaitMilliseconds?: number;
 
-        globalPlugins?: string[];
-        pluginProbeLocations?: string[];
+        globalPlugins?: ReadonlyArray<string>;
+        pluginProbeLocations?: ReadonlyArray<string>;
         allowLocalPluginLoads?: boolean;
     }
 
@@ -337,7 +333,7 @@ namespace ts.server {
                 case ContextEvent:
                     const { project, fileName } = event.data;
                     this.projectService.logger.info(`got context event, updating diagnostics for ${fileName}`);
-                    this.errorCheck.startNew(next => this.updateErrorCheck(next, [{ fileName, project }], this.changeSeq, (n) => n === this.changeSeq, 100));
+                    this.errorCheck.startNew(next => this.updateErrorCheck(next, [{ fileName, project }], 100));
                     break;
                 case ConfigFileDiagEvent:
                     const { triggerFile, configFileName, diagnostics } = event.data;
@@ -370,7 +366,7 @@ namespace ts.server {
                     msg += "\n" + (<StackTraceError>err).stack;
                 }
             }
-            this.logger.msg(msg, Msg.Err);
+            this.logger.err(msg);
         }
 
         public send(msg: protocol.Message) {
@@ -453,22 +449,23 @@ namespace ts.server {
             }
         }
 
-        private updateProjectStructure(seq: number, matchSeq: (seq: number) => boolean, ms = 1500) {
+        private updateProjectStructure() {
+            const ms = 1500;
+            const seq = this.changeSeq;
             this.host.setTimeout(() => {
-                if (matchSeq(seq)) {
+                if (this.changeSeq === seq) {
                     this.projectService.refreshInferredProjects();
                 }
             }, ms);
         }
 
-        private updateErrorCheck(next: NextStep, checkList: PendingErrorCheck[], seq: number, matchSeq: (seq: number) => boolean, ms = 1500, followMs = 200, requireOpen = true) {
-            if (followMs > ms) {
-                followMs = ms;
-            }
+        private updateErrorCheck(next: NextStep, checkList: PendingErrorCheck[], ms: number, requireOpen = true) {
+            const seq = this.changeSeq;
+            const followMs = Math.min(ms, 200);
 
             let index = 0;
             const checkOne = () => {
-                if (matchSeq(seq)) {
+                if (this.changeSeq === seq) {
                     const checkSpec = checkList[index];
                     index++;
                     if (checkSpec.project.containsFile(checkSpec.fileName, requireOpen)) {
@@ -483,7 +480,7 @@ namespace ts.server {
                 }
             };
 
-            if ((checkList.length > index) && (matchSeq(seq))) {
+            if (checkList.length > index && this.changeSeq === seq) {
                 next.delay(ms, checkOne);
             }
         }
@@ -1270,14 +1267,14 @@ namespace ts.server {
         }
 
         private getDiagnostics(next: NextStep, delay: number, fileNames: string[]): void {
-            const checkList = mapDefined(fileNames, uncheckedFileName => {
+            const checkList = mapDefined<string, PendingErrorCheck>(fileNames, uncheckedFileName => {
                 const fileName = toNormalizedPath(uncheckedFileName);
                 const project = this.projectService.getDefaultProjectForFile(fileName, /*refreshInferredProjects*/ true);
                 return project && { fileName, project };
             });
 
             if (checkList.length > 0) {
-                this.updateErrorCheck(next, checkList, this.changeSeq, (n) => n === this.changeSeq, delay);
+                this.updateErrorCheck(next, checkList, delay);
             }
         }
 
@@ -1291,7 +1288,7 @@ namespace ts.server {
                     scriptInfo.editContent(start, end, args.insertString);
                     this.changeSeq++;
                 }
-                this.updateProjectStructure(this.changeSeq, n => n === this.changeSeq);
+                this.updateProjectStructure();
             }
         }
 
@@ -1646,7 +1643,7 @@ namespace ts.server {
                 const checkList = fileNamesInProject.map(fileName => ({ fileName, project }));
                 // Project level error analysis runs on background files too, therefore
                 // doesn't require the file to be opened
-                this.updateErrorCheck(next, checkList, this.changeSeq, (n) => n === this.changeSeq, delay, 200, /*requireOpen*/ false);
+                this.updateErrorCheck(next, checkList, delay, /*requireOpen*/ false);
             }
         }
 
@@ -1960,7 +1957,7 @@ namespace ts.server {
                 return this.executeWithRequestId(request.seq, () => handler(request));
             }
             else {
-                this.logger.msg(`Unrecognized JSON command: ${JSON.stringify(request)}`, Msg.Err);
+                this.logger.err(`Unrecognized JSON command: ${JSON.stringify(request)}`);
                 this.output(undefined, CommandNames.Unknown, request.seq, `Unrecognized JSON command: ${request.command}`);
                 return { responseRequired: false };
             }
diff --git a/src/server/types.ts b/src/server/types.ts
index 07b94fe827e..4fc4356a4a9 100644
--- a/src/server/types.ts
+++ b/src/server/types.ts
@@ -9,7 +9,7 @@ declare namespace ts.server {
         data: any;
     }
 
-    type RequireResult = { module: {}, error: undefined } | { module: undefined, error: {} };
+    type RequireResult = { module: {}, error: undefined } | { module: undefined, error: { stack?: string, message?: string } };
     export interface ServerHost extends System {
         setTimeout(callback: (...args: any[]) => void, ms: number, ...args: any[]): any;
         clearTimeout(timeoutId: any): void;
diff --git a/src/server/utilities.ts b/src/server/utilities.ts
index fc88f11408a..0d4bc101ff6 100644
--- a/src/server/utilities.ts
+++ b/src/server/utilities.ts
@@ -17,22 +17,11 @@ namespace ts.server {
         loggingEnabled(): boolean;
         perftrc(s: string): void;
         info(s: string): void;
-        startGroup(): void;
-        endGroup(): void;
-        msg(s: string, type?: Msg.Types): void;
+        err(s: string): void;
+        group(logGroupEntries: (log: (msg: string) => void) => void): void;
         getLogFileName(): string;
     }
 
-    export namespace Msg {
-        export type Err = "Err";
-        export const Err: Err = "Err";
-        export type Info = "Info";
-        export const Info: Info = "Info";
-        export type Perf = "Perf";
-        export const Perf: Perf = "Perf";
-        export type Types = Err | Info | Perf;
-    }
-
     function getProjectRootPath(project: Project): Path {
         switch (project.projectKind) {
             case ProjectKind.Configured:
@@ -262,6 +251,15 @@ namespace ts.server {
         return arr as SortedArray<T>;
     }
 
+    export function toDeduplicatedSortedArray(arr: string[]): SortedArray<string> {
+        arr.sort();
+        filterMutate(arr, isNonDuplicateInSortedArray);
+        return arr as SortedArray<string>;
+    }
+    function isNonDuplicateInSortedArray<T>(value: T, index: number, array: T[]) {
+        return index === 0 || value !== array[index - 1];
+    }
+
     export function enumerateInsertsAndDeletes<T>(newItems: SortedReadonlyArray<T>, oldItems: SortedReadonlyArray<T>, inserted: (newItem: T) => void, deleted: (oldItem: T) => void, compare?: Comparer<T>) {
         compare = compare || compareValues;
         let newIndex = 0;
diff --git a/src/services/classifier.ts b/src/services/classifier.ts
index dc5d99bc490..4552d8bf985 100644
--- a/src/services/classifier.ts
+++ b/src/services/classifier.ts
@@ -260,11 +260,11 @@ namespace ts {
                                     templateStack.pop();
                                 }
                                 else {
-                                    Debug.assert(token === SyntaxKind.TemplateMiddle, "Should have been a template middle. Was " + token);
+                                    Debug.assertEqual(token, SyntaxKind.TemplateMiddle, "Should have been a template middle.");
                                 }
                             }
                             else {
-                                Debug.assert(lastTemplateStackToken === SyntaxKind.OpenBraceToken, "Should have been an open brace. Was: " + token);
+                                Debug.assertEqual(lastTemplateStackToken, SyntaxKind.OpenBraceToken, "Should have been an open brace");
                                 templateStack.pop();
                             }
                         }
diff --git a/src/services/formatting/rules.ts b/src/services/formatting/rules.ts
index 15bbf5041d3..2daf8d9d284 100644
--- a/src/services/formatting/rules.ts
+++ b/src/services/formatting/rules.ts
@@ -195,6 +195,7 @@ namespace ts.formatting {
         // Insert space after opening and before closing nonempty parenthesis
         public SpaceAfterOpenParen: Rule;
         public SpaceBeforeCloseParen: Rule;
+        public SpaceBetweenOpenParens: Rule;
         public NoSpaceBetweenParens: Rule;
         public NoSpaceAfterOpenParen: Rule;
         public NoSpaceBeforeCloseParen: Rule;
@@ -457,6 +458,7 @@ namespace ts.formatting {
             // Insert space after opening and before closing nonempty parenthesis
             this.SpaceAfterOpenParen = new Rule(RuleDescriptor.create3(SyntaxKind.OpenParenToken, Shared.TokenRange.Any), RuleOperation.create2(new RuleOperationContext(Rules.IsOptionEnabled("insertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis"), Rules.IsNonJsxSameLineTokenContext), RuleAction.Space));
             this.SpaceBeforeCloseParen = new Rule(RuleDescriptor.create2(Shared.TokenRange.Any, SyntaxKind.CloseParenToken), RuleOperation.create2(new RuleOperationContext(Rules.IsOptionEnabled("insertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis"), Rules.IsNonJsxSameLineTokenContext), RuleAction.Space));
+            this.SpaceBetweenOpenParens = new Rule(RuleDescriptor.create1(SyntaxKind.OpenParenToken, SyntaxKind.OpenParenToken), RuleOperation.create2(new RuleOperationContext(Rules.IsOptionEnabled("insertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis"), Rules.IsNonJsxSameLineTokenContext), RuleAction.Space));
             this.NoSpaceBetweenParens = new Rule(RuleDescriptor.create1(SyntaxKind.OpenParenToken, SyntaxKind.CloseParenToken), RuleOperation.create2(new RuleOperationContext(Rules.IsNonJsxSameLineTokenContext), RuleAction.Delete));
             this.NoSpaceAfterOpenParen = new Rule(RuleDescriptor.create3(SyntaxKind.OpenParenToken, Shared.TokenRange.Any), RuleOperation.create2(new RuleOperationContext(Rules.IsOptionDisabledOrUndefined("insertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis"), Rules.IsNonJsxSameLineTokenContext), RuleAction.Delete));
             this.NoSpaceBeforeCloseParen = new Rule(RuleDescriptor.create2(Shared.TokenRange.Any, SyntaxKind.CloseParenToken), RuleOperation.create2(new RuleOperationContext(Rules.IsOptionDisabledOrUndefined("insertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis"), Rules.IsNonJsxSameLineTokenContext), RuleAction.Delete));
@@ -544,7 +546,7 @@ namespace ts.formatting {
                 this.SpaceAfterComma, this.NoSpaceAfterComma,
                 this.SpaceAfterAnonymousFunctionKeyword, this.NoSpaceAfterAnonymousFunctionKeyword,
                 this.SpaceAfterKeywordInControl, this.NoSpaceAfterKeywordInControl,
-                this.SpaceAfterOpenParen, this.SpaceBeforeCloseParen, this.NoSpaceBetweenParens, this.NoSpaceAfterOpenParen, this.NoSpaceBeforeCloseParen,
+                this.SpaceAfterOpenParen, this.SpaceBeforeCloseParen, this.SpaceBetweenOpenParens, this.NoSpaceBetweenParens, this.NoSpaceAfterOpenParen, this.NoSpaceBeforeCloseParen,
                 this.SpaceAfterOpenBracket, this.SpaceBeforeCloseBracket, this.NoSpaceBetweenBrackets, this.NoSpaceAfterOpenBracket, this.NoSpaceBeforeCloseBracket,
                 this.SpaceAfterOpenBrace, this.SpaceBeforeCloseBrace, this.NoSpaceBetweenEmptyBraceBrackets, this.NoSpaceAfterOpenBrace, this.NoSpaceBeforeCloseBrace,
                 this.SpaceAfterTemplateHeadAndMiddle, this.SpaceBeforeTemplateMiddleAndTail, this.NoSpaceAfterTemplateHeadAndMiddle, this.NoSpaceBeforeTemplateMiddleAndTail,
diff --git a/src/services/jsTyping.ts b/src/services/jsTyping.ts
index 4de7bb3191d..5e7b7d424f8 100644
--- a/src/services/jsTyping.ts
+++ b/src/services/jsTyping.ts
@@ -35,7 +35,7 @@ namespace ts.JsTyping {
         "crypto", "stream", "util", "assert", "tty", "domain",
         "constants", "process", "v8", "timers", "console"];
 
-    const nodeCoreModules = arrayToMap(<string[]>nodeCoreModuleList, x => x);
+    const nodeCoreModules = arrayToSet(nodeCoreModuleList);
 
     /**
      * A map of loose file names to library names that we are confident require typings
diff --git a/src/services/services.ts b/src/services/services.ts
index 5a70ccca501..648cc6c8320 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1258,7 +1258,7 @@ namespace ts {
                         // We do not support the scenario where a host can modify a registered
                         // file's script kind, i.e. in one project some file is treated as ".ts"
                         // and in another as ".js"
-                        Debug.assert(hostFileInformation.scriptKind === oldSourceFile.scriptKind, "Registered script kind (" + oldSourceFile.scriptKind + ") should match new script kind (" + hostFileInformation.scriptKind + ") for file: " + path);
+                        Debug.assertEqual(hostFileInformation.scriptKind, oldSourceFile.scriptKind, "Registered script kind should match new script kind.", path);
 
                         return documentRegistry.updateDocumentWithKey(fileName, path, newSettings, documentRegistryBucketKey, hostFileInformation.scriptSnapshot, hostFileInformation.version, hostFileInformation.scriptKind);
                     }
diff --git a/src/services/signatureHelp.ts b/src/services/signatureHelp.ts
index f008c829116..2976b0d28ee 100644
--- a/src/services/signatureHelp.ts
+++ b/src/services/signatureHelp.ts
@@ -136,7 +136,9 @@ namespace ts.SignatureHelp {
 
             const kind = invocation.typeArguments && invocation.typeArguments.pos === list.pos ? ArgumentListKind.TypeArguments : ArgumentListKind.CallArguments;
             const argumentCount = getArgumentCount(list);
-            Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
+            if (argumentIndex !== 0) {
+                Debug.assertLessThan(argumentIndex, argumentCount);
+            }
             const argumentsSpan = getApplicableSpanForArguments(list, sourceFile);
             return { kind, invocation, argumentsSpan, argumentIndex, argumentCount };
         }
@@ -270,7 +272,9 @@ namespace ts.SignatureHelp {
             ? 1
             : (<TemplateExpression>tagExpression.template).templateSpans.length + 1;
 
-        Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
+        if (argumentIndex !== 0) {
+            Debug.assertLessThan(argumentIndex, argumentCount);
+        }
         return {
             kind: ArgumentListKind.TaggedTemplateArguments,
             invocation: tagExpression,
@@ -402,7 +406,9 @@ namespace ts.SignatureHelp {
             };
         });
 
-        Debug.assert(argumentIndex === 0 || argumentIndex < argumentCount, `argumentCount < argumentIndex, ${argumentCount} < ${argumentIndex}`);
+        if (argumentIndex !== 0) {
+            Debug.assertLessThan(argumentIndex, argumentCount);
+        }
 
         const selectedItemIndex = candidates.indexOf(resolvedSignature);
         Debug.assert(selectedItemIndex !== -1); // If candidates is non-empty it should always include bestSignature. We check for an empty candidates before calling this function.
diff --git a/src/services/transpile.ts b/src/services/transpile.ts
index 561c188c6cd..79a69b886d9 100644
--- a/src/services/transpile.ts
+++ b/src/services/transpile.ts
@@ -78,11 +78,11 @@ namespace ts {
             getSourceFile: (fileName) => fileName === normalizePath(inputFileName) ? sourceFile : undefined,
             writeFile: (name, text) => {
                 if (fileExtensionIs(name, ".map")) {
-                    Debug.assert(sourceMapText === undefined, `Unexpected multiple source map outputs for the file '${name}'`);
+                    Debug.assertEqual(sourceMapText, undefined, "Unexpected multiple source map outputs, file:", name);
                     sourceMapText = text;
                 }
                 else {
-                    Debug.assert(outputText === undefined, `Unexpected multiple outputs for the file: '${name}'`);
+                    Debug.assertEqual(outputText, undefined, "Unexpected multiple outputs, file:", name);
                     outputText = text;
                 }
             },
diff --git a/tests/baselines/reference/additionOperatorWithNullValueAndInvalidOperator.errors.txt b/tests/baselines/reference/additionOperatorWithNullValueAndInvalidOperator.errors.txt
index 5f0d78c59d5..891fe86dcd1 100644
--- a/tests/baselines/reference/additionOperatorWithNullValueAndInvalidOperator.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithNullValueAndInvalidOperator.errors.txt
@@ -1,14 +1,14 @@
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(11,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(12,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(13,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(14,14): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(15,14): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(16,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(19,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(20,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(21,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(22,11): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(23,11): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(11,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'boolean'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(12,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'Object'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(13,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(14,10): error TS2365: Operator '+' cannot be applied to types 'boolean' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(15,10): error TS2365: Operator '+' cannot be applied to types 'Object' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(16,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(19,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'Number'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(20,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'true'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(21,10): error TS2365: Operator '+' cannot be applied to types 'null' and '{ a: string; }'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(22,11): error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(23,11): error TS2365: Operator '+' cannot be applied to types 'null' and '() => void'.
 
 
 ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts (11 errors) ====
@@ -23,37 +23,37 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
     
     // null + boolean/Object
     var r1 = null + a;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'boolean'.
     var r2 = null + b;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'Object'.
     var r3 = null + c;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
     var r4 = a + null;
-                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'boolean' and 'null'.
     var r5 = b + null;
-                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'Object' and 'null'.
     var r6 = null + c;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
     
     // other cases
     var r7 = null + d;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'Number'.
     var r8 = null + true;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'true'.
     var r9 = null + { a: '' };
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and '{ a: string; }'.
     var r10 = null + foo();
-              ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'void'.
     var r11 = null + (() => { });
-              ~~~~
-!!! error TS2531: Object is possibly 'null'.
\ No newline at end of file
+              ~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and '() => void'.
\ No newline at end of file
diff --git a/tests/baselines/reference/additionOperatorWithNullValueAndValidOperator.errors.txt b/tests/baselines/reference/additionOperatorWithNullValueAndValidOperator.errors.txt
index db01a42c8bd..b722fd1be46 100644
--- a/tests/baselines/reference/additionOperatorWithNullValueAndValidOperator.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithNullValueAndValidOperator.errors.txt
@@ -1,13 +1,13 @@
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(15,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(16,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(17,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(18,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(19,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(20,14): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(21,14): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(22,15): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(23,17): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(24,20): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(15,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'number'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(16,10): error TS2365: Operator '+' cannot be applied to types 'null' and '1'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(17,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'E'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(18,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'E.a'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(19,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'E.a'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(20,10): error TS2365: Operator '+' cannot be applied to types 'number' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(21,10): error TS2365: Operator '+' cannot be applied to types '1' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(22,11): error TS2365: Operator '+' cannot be applied to types 'E' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(23,11): error TS2365: Operator '+' cannot be applied to types 'E.a' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts(24,11): error TS2365: Operator '+' cannot be applied to types 'E.a' and 'null'.
 
 
 ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndValidOperator.ts (10 errors) ====
@@ -26,35 +26,35 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
     
     // null + number/enum
     var r3 = null + b;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'number'.
     var r4 = null + 1;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and '1'.
     var r5 = null + c;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'E'.
     var r6 = null + E.a;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'E.a'.
     var r7 = null + E['a'];
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'E.a'.
     var r8 = b + null;
-                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'number' and 'null'.
     var r9 = 1 + null;
-                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types '1' and 'null'.
     var r10 = c + null
-                  ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E' and 'null'.
     var r11 = E.a + null;
-                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E.a' and 'null'.
     var r12 = E['a'] + null;
-                       ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E.a' and 'null'.
     
     // null + string
     var r13 = null + d;
diff --git a/tests/baselines/reference/additionOperatorWithOnlyNullValueOrUndefinedValue.errors.txt b/tests/baselines/reference/additionOperatorWithOnlyNullValueOrUndefinedValue.errors.txt
index aef66891be0..b4746ff1e68 100644
--- a/tests/baselines/reference/additionOperatorWithOnlyNullValueOrUndefinedValue.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithOnlyNullValueOrUndefinedValue.errors.txt
@@ -1,32 +1,20 @@
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(2,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(2,17): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(3,10): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(3,17): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(4,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(4,22): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(5,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(5,22): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(2,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(3,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(4,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(5,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 
 
-==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts (8 errors) ====
+==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts (4 errors) ====
     // bug 819721
     var r1 = null + null;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var r2 = null + undefined;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var r3 = undefined + null;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                         ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'null'.
     var r4 = undefined + undefined;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                         ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
\ No newline at end of file
+             ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
\ No newline at end of file
diff --git a/tests/baselines/reference/additionOperatorWithTypeParameter.errors.txt b/tests/baselines/reference/additionOperatorWithTypeParameter.errors.txt
index 478c4fdee3f..bdb81190b50 100644
--- a/tests/baselines/reference/additionOperatorWithTypeParameter.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithTypeParameter.errors.txt
@@ -8,8 +8,8 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(27,15): error TS2365: Operator '+' cannot be applied to types 'Object' and 'T'.
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(28,15): error TS2365: Operator '+' cannot be applied to types 'E' and 'T'.
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(29,15): error TS2365: Operator '+' cannot be applied to types 'void' and 'T'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(32,19): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(33,19): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(32,15): error TS2365: Operator '+' cannot be applied to types 'T' and 'null'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(33,15): error TS2365: Operator '+' cannot be applied to types 'T' and 'undefined'.
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(34,15): error TS2365: Operator '+' cannot be applied to types 'T' and 'T'.
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(35,15): error TS2365: Operator '+' cannot be applied to types 'T' and 'U'.
 tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithTypeParameter.ts(36,15): error TS2365: Operator '+' cannot be applied to types 'T' and '() => void'.
@@ -69,11 +69,11 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
     
         // other cases
         var r15 = t + null;
-                      ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                  ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'T' and 'null'.
         var r16 = t + undefined;
-                      ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                  ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'T' and 'undefined'.
         var r17 = t + t;
                   ~~~~~
 !!! error TS2365: Operator '+' cannot be applied to types 'T' and 'T'.
diff --git a/tests/baselines/reference/additionOperatorWithUndefinedValueAndInvalidOperands.errors.txt b/tests/baselines/reference/additionOperatorWithUndefinedValueAndInvalidOperands.errors.txt
index 06e8c67b105..6be41e81fd5 100644
--- a/tests/baselines/reference/additionOperatorWithUndefinedValueAndInvalidOperands.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithUndefinedValueAndInvalidOperands.errors.txt
@@ -1,14 +1,14 @@
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(11,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(12,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(13,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(14,14): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(15,14): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(16,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(19,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(20,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(21,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(22,11): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(23,11): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(11,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'boolean'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(12,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'Object'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(13,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(14,10): error TS2365: Operator '+' cannot be applied to types 'boolean' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(15,10): error TS2365: Operator '+' cannot be applied to types 'Object' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(16,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(19,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'Number'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(20,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'true'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(21,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and '{ a: string; }'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(22,11): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts(23,11): error TS2365: Operator '+' cannot be applied to types 'undefined' and '() => void'.
 
 
 ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndInvalidOperands.ts (11 errors) ====
@@ -23,37 +23,37 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
     
     // undefined + boolean/Object
     var r1 = undefined + a;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'boolean'.
     var r2 = undefined + b;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'Object'.
     var r3 = undefined + c;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
     var r4 = a + undefined;
-                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'boolean' and 'undefined'.
     var r5 = b + undefined;
-                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'Object' and 'undefined'.
     var r6 = undefined + c;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
     
     // other cases
     var r7 = undefined + d;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'Number'.
     var r8 = undefined + true;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'true'.
     var r9 = undefined + { a: '' };
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and '{ a: string; }'.
     var r10 = undefined + foo();
-              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+              ~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'void'.
     var r11 = undefined + (() => { });
-              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
\ No newline at end of file
+              ~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and '() => void'.
\ No newline at end of file
diff --git a/tests/baselines/reference/additionOperatorWithUndefinedValueAndValidOperator.errors.txt b/tests/baselines/reference/additionOperatorWithUndefinedValueAndValidOperator.errors.txt
index 04c0e2f3266..db2446aa3f9 100644
--- a/tests/baselines/reference/additionOperatorWithUndefinedValueAndValidOperator.errors.txt
+++ b/tests/baselines/reference/additionOperatorWithUndefinedValueAndValidOperator.errors.txt
@@ -1,13 +1,13 @@
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(15,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(16,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(17,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(18,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(19,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(20,14): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(21,14): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(22,15): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(23,17): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(24,20): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(15,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'number'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(16,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and '1'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(17,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(18,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E.a'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(19,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E.a'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(20,10): error TS2365: Operator '+' cannot be applied to types 'number' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(21,10): error TS2365: Operator '+' cannot be applied to types '1' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(22,11): error TS2365: Operator '+' cannot be applied to types 'E' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(23,11): error TS2365: Operator '+' cannot be applied to types 'E.a' and 'undefined'.
+tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts(24,11): error TS2365: Operator '+' cannot be applied to types 'E.a' and 'undefined'.
 
 
 ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithUndefinedValueAndValidOperator.ts (10 errors) ====
@@ -26,35 +26,35 @@ tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOpe
     
     // undefined + number/enum
     var r3 = undefined + b;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'number'.
     var r4 = undefined + 1;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and '1'.
     var r5 = undefined + c;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E'.
     var r6 = undefined + E.a;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E.a'.
     var r7 = undefined + E['a'];
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E.a'.
     var r8 = b + undefined;
-                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'number' and 'undefined'.
     var r9 = 1 + undefined;
-                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types '1' and 'undefined'.
     var r10 = c + undefined
-                  ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+              ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E' and 'undefined'.
     var r11 = E.a + undefined;
-                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+              ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E.a' and 'undefined'.
     var r12 = E['a'] + undefined;
-                       ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+              ~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E.a' and 'undefined'.
     
     // undefined + string
     var r13 = undefined + d;
diff --git a/tests/baselines/reference/bitwiseNotOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/bitwiseNotOperatorWithAnyOtherType.errors.txt
index 411c7099f11..795a9f0863d 100644
--- a/tests/baselines/reference/bitwiseNotOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/bitwiseNotOperatorWithAnyOtherType.errors.txt
@@ -1,14 +1,11 @@
 tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(34,24): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(35,24): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(46,26): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(46,33): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(47,26): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(47,33): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(48,26): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(48,38): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(46,26): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(47,26): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts(48,26): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts (8 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNotOperatorWithAnyOtherType.ts (5 errors) ====
     // ~ operator on any type
     
     var ANY: any;
@@ -59,20 +56,14 @@ tests/cases/conformance/expressions/unaryOperators/bitwiseNotOperator/bitwiseNot
     var ResultIsNumber14 = ~A.foo();
     var ResultIsNumber15 = ~(ANY + ANY1);
     var ResultIsNumber16 = ~(null + undefined);
-                             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber17 = ~(null + null);
-                             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                             ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber18 = ~(undefined + undefined);
-                             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                         ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                             ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     
     // multiple ~ operators
     var ResultIsNumber19 = ~~ANY;
diff --git a/tests/baselines/reference/checkTypePredicateForRedundantProperties.errors.txt b/tests/baselines/reference/checkTypePredicateForRedundantProperties.errors.txt
new file mode 100644
index 00000000000..a5cb9b0a098
--- /dev/null
+++ b/tests/baselines/reference/checkTypePredicateForRedundantProperties.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/compiler/checkTypePredicateForRedundantProperties.ts(1,35): error TS2300: Duplicate identifier 'a'.
+tests/cases/compiler/checkTypePredicateForRedundantProperties.ts(1,46): error TS2300: Duplicate identifier 'a'.
+
+
+==== tests/cases/compiler/checkTypePredicateForRedundantProperties.ts (2 errors) ====
+    function addProp2(x: any): x is { a: string; a: string; } {
+                                      ~
+!!! error TS2300: Duplicate identifier 'a'.
+                                                 ~
+!!! error TS2300: Duplicate identifier 'a'.
+        return true;
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/checkTypePredicateForRedundantProperties.js b/tests/baselines/reference/checkTypePredicateForRedundantProperties.js
new file mode 100644
index 00000000000..8f7be2bfbbc
--- /dev/null
+++ b/tests/baselines/reference/checkTypePredicateForRedundantProperties.js
@@ -0,0 +1,10 @@
+//// [checkTypePredicateForRedundantProperties.ts]
+function addProp2(x: any): x is { a: string; a: string; } {
+    return true;
+}
+
+
+//// [checkTypePredicateForRedundantProperties.js]
+function addProp2(x) {
+    return true;
+}
diff --git a/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.errors.txt b/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.errors.txt
index 08d8fd0c6d3..f7df532b20e 100644
--- a/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.errors.txt
+++ b/tests/baselines/reference/compoundAdditionAssignmentLHSCanBeAssigned.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(32,7): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(33,7): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(39,7): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(40,7): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(32,1): error TS2365: Operator '+=' cannot be applied to types 'number' and 'null'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(33,1): error TS2365: Operator '+=' cannot be applied to types 'number' and 'undefined'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(39,1): error TS2365: Operator '+=' cannot be applied to types 'E' and 'null'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts(40,1): error TS2365: Operator '+=' cannot be applied to types 'E' and 'undefined'.
 
 
 ==== tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentLHSCanBeAssigned.ts (4 errors) ====
@@ -37,22 +37,22 @@ tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmen
     x3 += 0;
     x3 += E.a;
     x3 += null;
-          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+    ~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'number' and 'null'.
     x3 += undefined;
-          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+    ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'number' and 'undefined'.
     
     var x4: E;
     x4 += a;
     x4 += 0;
     x4 += E.a;
     x4 += null;
-          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+    ~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'E' and 'null'.
     x4 += undefined;
-          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+    ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'E' and 'undefined'.
     
     var x5: boolean;
     x5 += a;
diff --git a/tests/baselines/reference/compoundAdditionAssignmentWithInvalidOperands.errors.txt b/tests/baselines/reference/compoundAdditionAssignmentWithInvalidOperands.errors.txt
index 1812065f149..e570f2f6cf0 100644
--- a/tests/baselines/reference/compoundAdditionAssignmentWithInvalidOperands.errors.txt
+++ b/tests/baselines/reference/compoundAdditionAssignmentWithInvalidOperands.errors.txt
@@ -3,22 +3,22 @@ tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmen
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(8,1): error TS2365: Operator '+=' cannot be applied to types 'boolean' and '0'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(9,1): error TS2365: Operator '+=' cannot be applied to types 'boolean' and 'E.a'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(10,1): error TS2365: Operator '+=' cannot be applied to types 'boolean' and '{}'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(11,7): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(12,7): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(11,1): error TS2365: Operator '+=' cannot be applied to types 'boolean' and 'null'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(12,1): error TS2365: Operator '+=' cannot be applied to types 'boolean' and 'undefined'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(15,1): error TS2365: Operator '+=' cannot be applied to types '{}' and 'void'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(16,1): error TS2365: Operator '+=' cannot be applied to types '{}' and 'true'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(17,1): error TS2365: Operator '+=' cannot be applied to types '{}' and '0'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(18,1): error TS2365: Operator '+=' cannot be applied to types '{}' and 'E.a'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(19,1): error TS2365: Operator '+=' cannot be applied to types '{}' and '{}'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(20,7): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(21,7): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(20,1): error TS2365: Operator '+=' cannot be applied to types '{}' and 'null'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(21,1): error TS2365: Operator '+=' cannot be applied to types '{}' and 'undefined'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(24,1): error TS2365: Operator '+=' cannot be applied to types 'void' and 'void'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(25,1): error TS2365: Operator '+=' cannot be applied to types 'void' and 'true'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(26,1): error TS2365: Operator '+=' cannot be applied to types 'void' and '0'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(27,1): error TS2365: Operator '+=' cannot be applied to types 'void' and 'E.a'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(28,1): error TS2365: Operator '+=' cannot be applied to types 'void' and '{}'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(29,7): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(30,7): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(29,1): error TS2365: Operator '+=' cannot be applied to types 'void' and 'null'.
+tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(30,1): error TS2365: Operator '+=' cannot be applied to types 'void' and 'undefined'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(33,1): error TS2365: Operator '+=' cannot be applied to types 'number' and 'void'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(34,1): error TS2365: Operator '+=' cannot be applied to types 'number' and 'true'.
 tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmentWithInvalidOperands.ts(35,1): error TS2365: Operator '+=' cannot be applied to types 'number' and '{}'.
@@ -49,11 +49,11 @@ tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmen
     ~~~~~~~~
 !!! error TS2365: Operator '+=' cannot be applied to types 'boolean' and '{}'.
     x1 += null;
-          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+    ~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'boolean' and 'null'.
     x1 += undefined;
-          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+    ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'boolean' and 'undefined'.
     
     var x2: {};
     x2 += a;
@@ -72,11 +72,11 @@ tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmen
     ~~~~~~~~
 !!! error TS2365: Operator '+=' cannot be applied to types '{}' and '{}'.
     x2 += null;
-          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+    ~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types '{}' and 'null'.
     x2 += undefined;
-          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+    ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types '{}' and 'undefined'.
     
     var x3: void;
     x3 += a;
@@ -95,11 +95,11 @@ tests/cases/conformance/expressions/assignmentOperator/compoundAdditionAssignmen
     ~~~~~~~~
 !!! error TS2365: Operator '+=' cannot be applied to types 'void' and '{}'.
     x3 += null;
-          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+    ~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'void' and 'null'.
     x3 += undefined;
-          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+    ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+=' cannot be applied to types 'void' and 'undefined'.
     
     var x4: number;
     x4 += a;
diff --git a/tests/baselines/reference/computedPropertyNames51_ES5.errors.txt b/tests/baselines/reference/computedPropertyNames51_ES5.errors.txt
new file mode 100644
index 00000000000..3ee876feaed
--- /dev/null
+++ b/tests/baselines/reference/computedPropertyNames51_ES5.errors.txt
@@ -0,0 +1,15 @@
+tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES5.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
+
+
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES5.ts (1 errors) ====
+    function f<T, K extends keyof T>() {
+        var t: T;
+        var k: K;
+        var v = {
+            [t]: 0,
+            ~~~
+!!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
+            [k]: 1
+        };
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames51_ES5.js b/tests/baselines/reference/computedPropertyNames51_ES5.js
new file mode 100644
index 00000000000..9f138b37f3d
--- /dev/null
+++ b/tests/baselines/reference/computedPropertyNames51_ES5.js
@@ -0,0 +1,21 @@
+//// [computedPropertyNames51_ES5.ts]
+function f<T, K extends keyof T>() {
+    var t: T;
+    var k: K;
+    var v = {
+        [t]: 0,
+        [k]: 1
+    };
+}
+
+
+//// [computedPropertyNames51_ES5.js]
+function f() {
+    var t;
+    var k;
+    var v = (_a = {},
+        _a[t] = 0,
+        _a[k] = 1,
+        _a);
+    var _a;
+}
diff --git a/tests/baselines/reference/computedPropertyNames51_ES6.errors.txt b/tests/baselines/reference/computedPropertyNames51_ES6.errors.txt
new file mode 100644
index 00000000000..b85ae8f48d0
--- /dev/null
+++ b/tests/baselines/reference/computedPropertyNames51_ES6.errors.txt
@@ -0,0 +1,15 @@
+tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES6.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
+
+
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES6.ts (1 errors) ====
+    function f<T, K extends keyof T>() {
+        var t: T;
+        var k: K;
+        var v = {
+            [t]: 0,
+            ~~~
+!!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
+            [k]: 1
+        };
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames51_ES6.js b/tests/baselines/reference/computedPropertyNames51_ES6.js
new file mode 100644
index 00000000000..361af9cc15a
--- /dev/null
+++ b/tests/baselines/reference/computedPropertyNames51_ES6.js
@@ -0,0 +1,20 @@
+//// [computedPropertyNames51_ES6.ts]
+function f<T, K extends keyof T>() {
+    var t: T;
+    var k: K;
+    var v = {
+        [t]: 0,
+        [k]: 1
+    };
+}
+
+
+//// [computedPropertyNames51_ES6.js]
+function f() {
+    var t;
+    var k;
+    var v = {
+        [t]: 0,
+        [k]: 1
+    };
+}
diff --git a/tests/baselines/reference/computedPropertyNames8_ES5.errors.txt b/tests/baselines/reference/computedPropertyNames8_ES5.errors.txt
index 9fbd14a92fb..56dbe16a523 100644
--- a/tests/baselines/reference/computedPropertyNames8_ES5.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames8_ES5.errors.txt
@@ -1,8 +1,7 @@
 tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES5.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES5.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
-==== tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES5.ts (2 errors) ====
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES5.ts (1 errors) ====
     function f<T, U extends string>() {
         var t: T;
         var u: U;
@@ -11,7 +10,5 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES5.ts(6,9
             ~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
             [u]: 1
-            ~~~
-!!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         };
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames8_ES6.errors.txt b/tests/baselines/reference/computedPropertyNames8_ES6.errors.txt
index 22674a3992c..9996f35f063 100644
--- a/tests/baselines/reference/computedPropertyNames8_ES6.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames8_ES6.errors.txt
@@ -1,8 +1,7 @@
 tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES6.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES6.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
-==== tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES6.ts (2 errors) ====
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES6.ts (1 errors) ====
     function f<T, U extends string>() {
         var t: T;
         var u: U;
@@ -11,7 +10,5 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames8_ES6.ts(6,9
             ~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
             [u]: 1
-            ~~~
-!!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         };
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.errors.txt b/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.errors.txt
index 1d37b20a3b3..708f175c002 100644
--- a/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.errors.txt
+++ b/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.errors.txt
@@ -34,7 +34,7 @@ tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(138,13): error T
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(141,32): error TS1005: '{' expected.
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(143,13): error TS1005: 'try' expected.
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(159,24): error TS1109: Expression expected.
-tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(159,30): error TS1005: '(' expected.
+tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(159,30): error TS1005: '{' expected.
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(159,31): error TS2304: Cannot find name 'Property'.
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(166,13): error TS2365: Operator '+=' cannot be applied to types 'number' and 'void'.
 tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(180,40): error TS2447: The '^' operator is not allowed for boolean types. Consider using '!==' instead.
@@ -323,7 +323,7 @@ tests/cases/compiler/constructorWithIncompleteTypeAnnotation.ts(261,1): error TS
                            ~~~~~
 !!! error TS1109: Expression expected.
                                  ~
-!!! error TS1005: '(' expected.
+!!! error TS1005: '{' expected.
                                   ~~~~~~~~
 !!! error TS2304: Cannot find name 'Property'.
                 retVal += c.Member();
diff --git a/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.js b/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.js
index 8e9dc6da688..f33c4b6d316 100644
--- a/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.js
+++ b/tests/baselines/reference/constructorWithIncompleteTypeAnnotation.js
@@ -441,7 +441,7 @@ var BasicFeatures = (function () {
         var xx = c;
         retVal += ;
         try { }
-        catch () { }
+        catch (_a) { }
         Property;
         retVal += c.Member();
         retVal += xx.Foo() ? 0 : 1;
diff --git a/tests/baselines/reference/decrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt b/tests/baselines/reference/decrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
index 33e31bc9478..ff54b4d52c6 100644
--- a/tests/baselines/reference/decrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
+++ b/tests/baselines/reference/decrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
@@ -19,27 +19,21 @@ tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOp
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(46,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(47,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,34): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,34): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,27): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,39): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,27): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(51,26): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(52,26): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(54,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(55,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,25): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,32): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,25): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,25): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,32): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,25): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,25): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,37): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,25): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(59,24): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(60,24): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(63,3): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
@@ -58,7 +52,7 @@ tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOp
 tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts(72,12): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts (58 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOperatorWithAnyOtherTypeInvalidOperations.ts (52 errors) ====
     // -- operator on any type
     var ANY1: any;
     var ANY2: any[] = ["", ""];
@@ -149,24 +143,18 @@ tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOp
     var ResultIsNumber19 = --(null + undefined);
                              ~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber20 = --(null + null);
                              ~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                              ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber21 = --(undefined + undefined);
                              ~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     var ResultIsNumber22 = --obj1.x;
                              ~~~~~~
 !!! error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
@@ -183,24 +171,18 @@ tests/cases/conformance/expressions/unaryOperators/decrementOperator/decrementOp
     var ResultIsNumber26 = (null + undefined)--;
                            ~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                   ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                            ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber27 = (null + null)--;
                            ~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                   ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                            ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber28 = (undefined + undefined)--;
                            ~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                        ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                            ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     var ResultIsNumber29 = obj1.x--;
                            ~~~~~~
 !!! error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
diff --git a/tests/baselines/reference/deleteOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/deleteOperatorWithAnyOtherType.errors.txt
index f2260b11036..5ea3f6135c1 100644
--- a/tests/baselines/reference/deleteOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/deleteOperatorWithAnyOtherType.errors.txt
@@ -9,15 +9,12 @@ tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperator
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(42,32): error TS2703: The operand of a delete operator must be a property reference.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(43,32): error TS2703: The operand of a delete operator must be a property reference.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(44,33): error TS2703: The operand of a delete operator must be a property reference.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(45,33): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(45,33): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(45,33): error TS2703: The operand of a delete operator must be a property reference.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(45,40): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(46,33): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(46,33): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(46,33): error TS2703: The operand of a delete operator must be a property reference.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(46,40): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(47,33): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(47,33): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(47,33): error TS2703: The operand of a delete operator must be a property reference.
-tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(47,45): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(50,32): error TS2703: The operand of a delete operator must be a property reference.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(50,39): error TS2703: The operand of a delete operator must be a property reference.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(51,32): error TS2703: The operand of a delete operator must be a property reference.
@@ -28,7 +25,7 @@ tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperator
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts(57,8): error TS2703: The operand of a delete operator must be a property reference.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts (28 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorWithAnyOtherType.ts (25 errors) ====
     // delete  operator on any type
     
     var ANY: any;
@@ -96,26 +93,20 @@ tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperator
                                     ~~~~~~~~~~
 !!! error TS2703: The operand of a delete operator must be a property reference.
     var ResultIsBoolean17 = delete (null + undefined);
-                                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                                    ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
                                     ~~~~~~~~~~~~~~~~
 !!! error TS2703: The operand of a delete operator must be a property reference.
-                                           ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
     var ResultIsBoolean18 = delete (null + null);
-                                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                                    ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
                                     ~~~~~~~~~~~
 !!! error TS2703: The operand of a delete operator must be a property reference.
-                                           ~~~~
-!!! error TS2531: Object is possibly 'null'.
     var ResultIsBoolean19 = delete (undefined + undefined);
-                                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                                    ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
                                     ~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2703: The operand of a delete operator must be a property reference.
-                                                ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
     
     // multiple delete  operators
     var ResultIsBoolean20 = delete delete ANY;
diff --git a/tests/baselines/reference/emitter.noCatchBinding.esnext.js b/tests/baselines/reference/emitter.noCatchBinding.esnext.js
new file mode 100644
index 00000000000..f47a947ca1a
--- /dev/null
+++ b/tests/baselines/reference/emitter.noCatchBinding.esnext.js
@@ -0,0 +1,22 @@
+//// [emitter.noCatchBinding.esnext.ts]
+function f() {
+    try { } catch { }
+    try { } catch { 
+        try { } catch { }
+    }
+    try { } catch { } finally { }
+}
+
+//// [emitter.noCatchBinding.esnext.js]
+function f() {
+    try { }
+    catch { }
+    try { }
+    catch {
+        try { }
+        catch { }
+    }
+    try { }
+    catch { }
+    finally { }
+}
diff --git a/tests/baselines/reference/emitter.noCatchBinding.esnext.symbols b/tests/baselines/reference/emitter.noCatchBinding.esnext.symbols
new file mode 100644
index 00000000000..91242f5b01c
--- /dev/null
+++ b/tests/baselines/reference/emitter.noCatchBinding.esnext.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/conformance/emitter/esnext/noCatchBinding/emitter.noCatchBinding.esnext.ts ===
+function f() {
+>f : Symbol(f, Decl(emitter.noCatchBinding.esnext.ts, 0, 0))
+
+    try { } catch { }
+    try { } catch { 
+        try { } catch { }
+    }
+    try { } catch { } finally { }
+}
diff --git a/tests/baselines/reference/emitter.noCatchBinding.esnext.types b/tests/baselines/reference/emitter.noCatchBinding.esnext.types
new file mode 100644
index 00000000000..70c2b728a5d
--- /dev/null
+++ b/tests/baselines/reference/emitter.noCatchBinding.esnext.types
@@ -0,0 +1,10 @@
+=== tests/cases/conformance/emitter/esnext/noCatchBinding/emitter.noCatchBinding.esnext.ts ===
+function f() {
+>f : () => void
+
+    try { } catch { }
+    try { } catch { 
+        try { } catch { }
+    }
+    try { } catch { } finally { }
+}
diff --git a/tests/baselines/reference/importCallExpressionAsyncES3System.types b/tests/baselines/reference/importCallExpressionAsyncES3System.types
index 4f6a2bb31be..90c981c01ca 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES3System.types
+++ b/tests/baselines/reference/importCallExpressionAsyncES3System.types
@@ -3,9 +3,9 @@ export async function fn() {
 >fn : () => Promise<void>
 
     const req = await import('./test') // ONE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
@@ -16,9 +16,9 @@ export class cl1 {
 >m : () => Promise<void>
 
         const req = await import('./test') // TWO
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -32,9 +32,9 @@ export const obj = {
 >async () => {        const req = await import('./test') // THREE    } : () => Promise<void>
 
         const req = await import('./test') // THREE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -51,9 +51,9 @@ export class cl2 {
 >async () => {            const req = await import('./test') // FOUR        } : () => Promise<void>
 
             const req = await import('./test') // FOUR
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
         }
     }
@@ -64,9 +64,9 @@ export const l = async () => {
 >async () => {    const req = await import('./test') // FIVE} : () => Promise<void>
 
     const req = await import('./test') // FIVE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
diff --git a/tests/baselines/reference/importCallExpressionAsyncES5System.types b/tests/baselines/reference/importCallExpressionAsyncES5System.types
index 4f6a2bb31be..90c981c01ca 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES5System.types
+++ b/tests/baselines/reference/importCallExpressionAsyncES5System.types
@@ -3,9 +3,9 @@ export async function fn() {
 >fn : () => Promise<void>
 
     const req = await import('./test') // ONE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
@@ -16,9 +16,9 @@ export class cl1 {
 >m : () => Promise<void>
 
         const req = await import('./test') // TWO
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -32,9 +32,9 @@ export const obj = {
 >async () => {        const req = await import('./test') // THREE    } : () => Promise<void>
 
         const req = await import('./test') // THREE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -51,9 +51,9 @@ export class cl2 {
 >async () => {            const req = await import('./test') // FOUR        } : () => Promise<void>
 
             const req = await import('./test') // FOUR
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
         }
     }
@@ -64,9 +64,9 @@ export const l = async () => {
 >async () => {    const req = await import('./test') // FIVE} : () => Promise<void>
 
     const req = await import('./test') // FIVE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
diff --git a/tests/baselines/reference/importCallExpressionAsyncES6System.types b/tests/baselines/reference/importCallExpressionAsyncES6System.types
index 4f6a2bb31be..90c981c01ca 100644
--- a/tests/baselines/reference/importCallExpressionAsyncES6System.types
+++ b/tests/baselines/reference/importCallExpressionAsyncES6System.types
@@ -3,9 +3,9 @@ export async function fn() {
 >fn : () => Promise<void>
 
     const req = await import('./test') // ONE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
@@ -16,9 +16,9 @@ export class cl1 {
 >m : () => Promise<void>
 
         const req = await import('./test') // TWO
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -32,9 +32,9 @@ export const obj = {
 >async () => {        const req = await import('./test') // THREE    } : () => Promise<void>
 
         const req = await import('./test') // THREE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
     }
 }
@@ -51,9 +51,9 @@ export class cl2 {
 >async () => {            const req = await import('./test') // FOUR        } : () => Promise<void>
 
             const req = await import('./test') // FOUR
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
         }
     }
@@ -64,9 +64,9 @@ export const l = async () => {
 >async () => {    const req = await import('./test') // FIVE} : () => Promise<void>
 
     const req = await import('./test') // FIVE
->req : typeof "tests/cases/conformance/dynamicImport/test"
->await import('./test') : typeof "tests/cases/conformance/dynamicImport/test"
->import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test">
+>req : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>await import('./test') : typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }
+>import('./test') : Promise<typeof "tests/cases/conformance/dynamicImport/test" & { default: typeof "tests/cases/conformance/dynamicImport/test"; }>
 >'./test' : "./test"
 }
 
diff --git a/tests/baselines/reference/importCallExpressionES5System.types b/tests/baselines/reference/importCallExpressionES5System.types
index e97f722b14f..02bd64142d4 100644
--- a/tests/baselines/reference/importCallExpressionES5System.types
+++ b/tests/baselines/reference/importCallExpressionES5System.types
@@ -5,41 +5,41 @@ export function foo() { return "foo"; }
 
 === tests/cases/conformance/dynamicImport/1.ts ===
 import("./0");
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 var p1 = import("./0");
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 p1.then(zero => {
 >p1.then(zero => {    return zero.foo();}) : Promise<string>
->p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0") => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => string
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 
     return zero.foo();
 >zero.foo() : string
 >zero.foo : () => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 >foo : () => string
 
 });
 
 export var p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 function foo() {
 >foo : () => void
 
     const p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 }
 
@@ -50,8 +50,8 @@ class C {
 >method : () => void
 
         const loadAsync = import ("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
     }
 }
@@ -63,8 +63,8 @@ export class D {
 >method : () => void
 
         const loadAsync = import ("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
     }
 }
diff --git a/tests/baselines/reference/importCallExpressionES6System.types b/tests/baselines/reference/importCallExpressionES6System.types
index e97f722b14f..02bd64142d4 100644
--- a/tests/baselines/reference/importCallExpressionES6System.types
+++ b/tests/baselines/reference/importCallExpressionES6System.types
@@ -5,41 +5,41 @@ export function foo() { return "foo"; }
 
 === tests/cases/conformance/dynamicImport/1.ts ===
 import("./0");
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 var p1 = import("./0");
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 p1.then(zero => {
 >p1.then(zero => {    return zero.foo();}) : Promise<string>
->p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0") => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => string
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 
     return zero.foo();
 >zero.foo() : string
 >zero.foo : () => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 >foo : () => string
 
 });
 
 export var p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 function foo() {
 >foo : () => void
 
     const p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 }
 
@@ -50,8 +50,8 @@ class C {
 >method : () => void
 
         const loadAsync = import ("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
     }
 }
@@ -63,8 +63,8 @@ export class D {
 >method : () => void
 
         const loadAsync = import ("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import ("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
     }
 }
diff --git a/tests/baselines/reference/importCallExpressionInSystem1.types b/tests/baselines/reference/importCallExpressionInSystem1.types
index 661d27d1469..a82d8176753 100644
--- a/tests/baselines/reference/importCallExpressionInSystem1.types
+++ b/tests/baselines/reference/importCallExpressionInSystem1.types
@@ -5,40 +5,40 @@ export function foo() { return "foo"; }
 
 === tests/cases/conformance/dynamicImport/1.ts ===
 import("./0");
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 var p1 = import("./0");
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 p1.then(zero => {
 >p1.then(zero => {    return zero.foo();}) : Promise<string>
->p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0") => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>p1.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>p1 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>zero => {    return zero.foo();} : (zero: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => string
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 
     return zero.foo();
 >zero.foo() : string
 >zero.foo : () => string
->zero : typeof "tests/cases/conformance/dynamicImport/0"
+>zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 >foo : () => string
 
 });
 
 export var p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
 function foo() {
 >foo : () => void
 
     const p2 = import("./0");
->p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>p2 : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 }
diff --git a/tests/baselines/reference/importCallExpressionInSystem2.types b/tests/baselines/reference/importCallExpressionInSystem2.types
index 44b17eb51fd..160da81b214 100644
--- a/tests/baselines/reference/importCallExpressionInSystem2.types
+++ b/tests/baselines/reference/importCallExpressionInSystem2.types
@@ -41,6 +41,6 @@ function foo(x: Promise<any>) {
 foo(import("./0"));
 >foo(import("./0")) : void
 >foo : (x: Promise<any>) => void
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
diff --git a/tests/baselines/reference/importCallExpressionInSystem3.types b/tests/baselines/reference/importCallExpressionInSystem3.types
index e517be6e722..08bf03fb506 100644
--- a/tests/baselines/reference/importCallExpressionInSystem3.types
+++ b/tests/baselines/reference/importCallExpressionInSystem3.types
@@ -14,9 +14,9 @@ async function foo() {
     class C extends (await import("./0")).B {}
 >C : C
 >(await import("./0")).B : B
->(await import("./0")) : typeof "tests/cases/conformance/dynamicImport/0"
->await import("./0") : typeof "tests/cases/conformance/dynamicImport/0"
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>(await import("./0")) : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
+>await import("./0") : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 >B : typeof B
 
diff --git a/tests/baselines/reference/importCallExpressionInSystem4.types b/tests/baselines/reference/importCallExpressionInSystem4.types
index 156247851c9..c9f2b2e5211 100644
--- a/tests/baselines/reference/importCallExpressionInSystem4.types
+++ b/tests/baselines/reference/importCallExpressionInSystem4.types
@@ -24,27 +24,27 @@ class C {
 >C : C
 
     private myModule = import("./0");
->myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
     method() {
 >method : () => void
 
         const loadAsync = import("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
         this.myModule.then(Zero => {
 >this.myModule.then(Zero => {            console.log(Zero.foo());        }, async err => {            console.log(err);            let one = await import("./1");            console.log(one.backup());        }) : Promise<void>
->this.myModule.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->this.myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>this.myModule.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>this.myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >this : this
->myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->Zero => {            console.log(Zero.foo());        } : (Zero: typeof "tests/cases/conformance/dynamicImport/0") => void
->Zero : typeof "tests/cases/conformance/dynamicImport/0"
+>myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>Zero => {            console.log(Zero.foo());        } : (Zero: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => void
+>Zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 
             console.log(Zero.foo());
 >console.log(Zero.foo()) : any
@@ -53,7 +53,7 @@ class C {
 >log : any
 >Zero.foo() : string
 >Zero.foo : () => string
->Zero : typeof "tests/cases/conformance/dynamicImport/0"
+>Zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 >foo : () => string
 
         }, async err => {
@@ -68,9 +68,9 @@ class C {
 >err : any
 
             let one = await import("./1");
->one : typeof "tests/cases/conformance/dynamicImport/1"
->await import("./1") : typeof "tests/cases/conformance/dynamicImport/1"
->import("./1") : Promise<typeof "tests/cases/conformance/dynamicImport/1">
+>one : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
+>await import("./1") : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
+>import("./1") : Promise<typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }>
 >"./1" : "./1"
 
             console.log(one.backup());
@@ -80,7 +80,7 @@ class C {
 >log : any
 >one.backup() : string
 >one.backup : () => string
->one : typeof "tests/cases/conformance/dynamicImport/1"
+>one : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
 >backup : () => string
 
         });
@@ -91,27 +91,27 @@ export class D {
 >D : D
 
     private myModule = import("./0");
->myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
     method() {
 >method : () => void
 
         const loadAsync = import("./0");
->loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>loadAsync : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>import("./0") : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >"./0" : "./0"
 
         this.myModule.then(Zero => {
 >this.myModule.then(Zero => {            console.log(Zero.foo());        }, async err => {            console.log(err);            let one = await import("./1");            console.log(one.backup());        }) : Promise<void>
->this.myModule.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->this.myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
+>this.myModule.then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>this.myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
 >this : this
->myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0">
->then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0", TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0") => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
->Zero => {            console.log(Zero.foo());        } : (Zero: typeof "tests/cases/conformance/dynamicImport/0") => void
->Zero : typeof "tests/cases/conformance/dynamicImport/0"
+>myModule : Promise<typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }>
+>then : <TResult1 = typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }, TResult2 = never>(onfulfilled?: (value: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>Zero => {            console.log(Zero.foo());        } : (Zero: typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }) => void
+>Zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 
             console.log(Zero.foo());
 >console.log(Zero.foo()) : any
@@ -120,7 +120,7 @@ export class D {
 >log : any
 >Zero.foo() : string
 >Zero.foo : () => string
->Zero : typeof "tests/cases/conformance/dynamicImport/0"
+>Zero : typeof "tests/cases/conformance/dynamicImport/0" & { default: typeof "tests/cases/conformance/dynamicImport/0"; }
 >foo : () => string
 
         }, async err => {
@@ -135,9 +135,9 @@ export class D {
 >err : any
 
             let one = await import("./1");
->one : typeof "tests/cases/conformance/dynamicImport/1"
->await import("./1") : typeof "tests/cases/conformance/dynamicImport/1"
->import("./1") : Promise<typeof "tests/cases/conformance/dynamicImport/1">
+>one : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
+>await import("./1") : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
+>import("./1") : Promise<typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }>
 >"./1" : "./1"
 
             console.log(one.backup());
@@ -147,7 +147,7 @@ export class D {
 >log : any
 >one.backup() : string
 >one.backup : () => string
->one : typeof "tests/cases/conformance/dynamicImport/1"
+>one : typeof "tests/cases/conformance/dynamicImport/1" & { default: typeof "tests/cases/conformance/dynamicImport/1"; }
 >backup : () => string
 
         });
diff --git a/tests/baselines/reference/incrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt b/tests/baselines/reference/incrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
index afdddab86a7..690f3391933 100644
--- a/tests/baselines/reference/incrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
+++ b/tests/baselines/reference/incrementOperatorWithAnyOtherTypeInvalidOperations.errors.txt
@@ -19,27 +19,21 @@ tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOp
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(46,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(47,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,34): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(48,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,34): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(49,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,26): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,27): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,39): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(50,27): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(51,26): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(52,26): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(54,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(55,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,25): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,32): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(56,25): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,25): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,32): error TS2531: Object is possibly 'null'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(57,25): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,24): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,25): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,37): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(58,25): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(59,24): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(60,24): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(63,3): error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
@@ -53,7 +47,7 @@ tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOp
 tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts(69,12): error TS1109: Expression expected.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts (53 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOperatorWithAnyOtherTypeInvalidOperations.ts (47 errors) ====
     // ++ operator on any type
     var ANY1: any;
     var ANY2: any[] = [1, 2];
@@ -144,24 +138,18 @@ tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOp
     var ResultIsNumber19 = ++(null + undefined);
                              ~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber20 = ++(null + null);
                              ~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                              ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber21 = ++(undefined + undefined);
                              ~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     var ResultIsNumber22 = ++obj1.x;
                              ~~~~~~
 !!! error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
@@ -178,24 +166,18 @@ tests/cases/conformance/expressions/unaryOperators/incrementOperator/incrementOp
     var ResultIsNumber26 = (null + undefined)++;
                            ~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                   ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                            ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber27 = (null + null)++;
                            ~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                   ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                            ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber28 = (undefined + undefined)++;
                            ~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2357: The operand of an increment or decrement operator must be a variable or a property access.
-                            ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                        ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                            ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     var ResultIsNumber29 = obj1.x++;
                            ~~~~~~
 !!! error TS2356: An arithmetic operand must be of type 'any', 'number' or an enum type.
diff --git a/tests/baselines/reference/invalidTryStatements2.errors.txt b/tests/baselines/reference/invalidTryStatements2.errors.txt
index f2e88cfdc22..a7c436236f2 100644
--- a/tests/baselines/reference/invalidTryStatements2.errors.txt
+++ b/tests/baselines/reference/invalidTryStatements2.errors.txt
@@ -1,24 +1,23 @@
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(3,13): error TS1005: '(' expected.
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(6,5): error TS1005: 'try' expected.
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(12,5): error TS1005: 'try' expected.
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(13,5): error TS1005: 'try' expected.
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(22,5): error TS1005: 'try' expected.
-tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(26,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(2,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(6,12): error TS1005: 'finally' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(10,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(11,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(15,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(17,5): error TS1005: 'try' expected.
+tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(19,20): error TS1003: Identifier expected.
 
 
-==== tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts (6 errors) ====
+==== tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts (7 errors) ====
     function fn() {
-        try {
-        } catch { // syntax error, missing '(x)'
-                ~
-!!! error TS1005: '(' expected.
-        }
-    
         catch(x) { } // error missing try
         ~~~~~
 !!! error TS1005: 'try' expected.
     
-        finally{ } // potential error; can be absorbed by the 'catch'
+        finally { } // potential error; can be absorbed by the 'catch'
+    
+        try { }; // error missing finally
+               ~
+!!! error TS1005: 'finally' expected.
     }
     
     function fn2() {
@@ -28,22 +27,18 @@ tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts(26,5):
         catch (x) { } // error missing try
         ~~~~~
 !!! error TS1005: 'try' expected.
+        
+        try { } finally { } // statement is here, so the 'catch' clause above doesn't absorb errors from the 'finally' clause below
     
-        // no error
-        try {
-        }
-        finally {
-        }
-    
-        // error missing try
-        finally {
+        finally { } // error missing try
         ~~~~~~~
 !!! error TS1005: 'try' expected.
-        }
-    
-        // error missing try
-        catch (x) {
+        
+        catch (x) { } // error missing try
         ~~~~~
 !!! error TS1005: 'try' expected.
-        }
+    
+        try { } catch () { } // error missing catch binding
+                       ~
+!!! error TS1003: Identifier expected.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/invalidTryStatements2.js b/tests/baselines/reference/invalidTryStatements2.js
index 118b607817a..50aff00c515 100644
--- a/tests/baselines/reference/invalidTryStatements2.js
+++ b/tests/baselines/reference/invalidTryStatements2.js
@@ -1,43 +1,34 @@
 //// [invalidTryStatements2.ts]
 function fn() {
-    try {
-    } catch { // syntax error, missing '(x)'
-    }
-
     catch(x) { } // error missing try
 
-    finally{ } // potential error; can be absorbed by the 'catch'
+    finally { } // potential error; can be absorbed by the 'catch'
+
+    try { }; // error missing finally
 }
 
 function fn2() {
     finally { } // error missing try
     catch (x) { } // error missing try
+    
+    try { } finally { } // statement is here, so the 'catch' clause above doesn't absorb errors from the 'finally' clause below
 
-    // no error
-    try {
-    }
-    finally {
-    }
+    finally { } // error missing try
+    
+    catch (x) { } // error missing try
 
-    // error missing try
-    finally {
-    }
-
-    // error missing try
-    catch (x) {
-    }
+    try { } catch () { } // error missing catch binding
 }
 
 //// [invalidTryStatements2.js]
 function fn() {
-    try {
-    }
-    catch () {
-    }
     try {
     }
     catch (x) { } // error missing try
     finally { } // potential error; can be absorbed by the 'catch'
+    try { }
+    finally { }
+    ; // error missing finally
 }
 function fn2() {
     try {
@@ -46,19 +37,14 @@ function fn2() {
     try {
     }
     catch (x) { } // error missing try
-    // no error
+    try { }
+    finally { } // statement is here, so the 'catch' clause above doesn't absorb errors from the 'finally' clause below
     try {
     }
-    finally {
-    }
-    // error missing try
+    finally { } // error missing try
     try {
     }
-    finally {
-    }
-    // error missing try
-    try {
-    }
-    catch (x) {
-    }
+    catch (x) { } // error missing try
+    try { }
+    catch () { } // error missing catch binding
 }
diff --git a/tests/baselines/reference/jsdocCastCommentEmit.js b/tests/baselines/reference/jsdocCastCommentEmit.js
new file mode 100644
index 00000000000..d071f8f6b2b
--- /dev/null
+++ b/tests/baselines/reference/jsdocCastCommentEmit.js
@@ -0,0 +1,17 @@
+//// [jsdocCastCommentEmit.ts]
+// allowJs: true
+// checkJs: true
+// outDir: out/
+// filename: input.js
+function f() {
+    return /* @type {number} */ 42;
+}
+
+//// [jsdocCastCommentEmit.js]
+// allowJs: true
+// checkJs: true
+// outDir: out/
+// filename: input.js
+function f() {
+    return /* @type {number} */ 42;
+}
diff --git a/tests/baselines/reference/jsdocCastCommentEmit.symbols b/tests/baselines/reference/jsdocCastCommentEmit.symbols
new file mode 100644
index 00000000000..5490315bc19
--- /dev/null
+++ b/tests/baselines/reference/jsdocCastCommentEmit.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/jsdocCastCommentEmit.ts ===
+// allowJs: true
+// checkJs: true
+// outDir: out/
+// filename: input.js
+function f() {
+>f : Symbol(f, Decl(jsdocCastCommentEmit.ts, 0, 0))
+
+    return /* @type {number} */ 42;
+}
diff --git a/tests/baselines/reference/jsdocCastCommentEmit.types b/tests/baselines/reference/jsdocCastCommentEmit.types
new file mode 100644
index 00000000000..3d4c3e47e46
--- /dev/null
+++ b/tests/baselines/reference/jsdocCastCommentEmit.types
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/jsdocCastCommentEmit.ts ===
+// allowJs: true
+// checkJs: true
+// outDir: out/
+// filename: input.js
+function f() {
+>f : () => number
+
+    return /* @type {number} */ 42;
+>42 : 42
+}
diff --git a/tests/baselines/reference/logicalNotOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/logicalNotOperatorWithAnyOtherType.errors.txt
index 0cb9869ca4c..ad951adf5f7 100644
--- a/tests/baselines/reference/logicalNotOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/logicalNotOperatorWithAnyOtherType.errors.txt
@@ -1,13 +1,10 @@
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(45,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(45,34): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(46,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(46,34): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(47,27): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(47,39): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(45,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(46,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(47,27): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts(57,1): error TS2695: Left side of comma operator is unused and has no side effects.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts (7 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNotOperatorWithAnyOtherType.ts (4 errors) ====
     // ! operator on any type
     
     var ANY: any;
@@ -53,20 +50,14 @@ tests/cases/conformance/expressions/unaryOperators/logicalNotOperator/logicalNot
     var ResultIsBoolean15 = !A.foo();
     var ResultIsBoolean16 = !(ANY + ANY1);
     var ResultIsBoolean17 = !(null + undefined);
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsBoolean18 = !(null + null);
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                              ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsBoolean19 = !(undefined + undefined);
-                              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     
     // multiple ! operators
     var ResultIsBoolean20 = !!ANY;
diff --git a/tests/baselines/reference/mixingApparentTypeOverrides.js b/tests/baselines/reference/mixingApparentTypeOverrides.js
new file mode 100644
index 00000000000..20db894abb8
--- /dev/null
+++ b/tests/baselines/reference/mixingApparentTypeOverrides.js
@@ -0,0 +1,84 @@
+//// [mixingApparentTypeOverrides.ts]
+type Constructor<T> = new(...args: any[]) => T;
+function Tagged<T extends Constructor<{}>>(Base: T) {
+  return class extends Base {
+    _tag: string;
+    constructor(...args: any[]) {
+      super(...args);
+      this._tag = "";
+    }
+  };
+}
+
+class A {
+  toString () {
+    return "class A";
+  }
+}
+
+class B extends Tagged(A) {
+  toString () { // Should not be an error
+    return "class B";
+  }
+}
+
+class C extends A {
+  toString () { // Should not be an error
+    return "class C";
+  }
+}
+
+//// [mixingApparentTypeOverrides.js]
+var __extends = (this && this.__extends) || (function () {
+    var extendStatics = Object.setPrototypeOf ||
+        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
+        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
+    return function (d, b) {
+        extendStatics(d, b);
+        function __() { this.constructor = d; }
+        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+    };
+})();
+function Tagged(Base) {
+    return (function (_super) {
+        __extends(class_1, _super);
+        function class_1() {
+            var args = [];
+            for (var _i = 0; _i < arguments.length; _i++) {
+                args[_i] = arguments[_i];
+            }
+            var _this = _super.apply(this, args) || this;
+            _this._tag = "";
+            return _this;
+        }
+        return class_1;
+    }(Base));
+}
+var A = (function () {
+    function A() {
+    }
+    A.prototype.toString = function () {
+        return "class A";
+    };
+    return A;
+}());
+var B = (function (_super) {
+    __extends(B, _super);
+    function B() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    B.prototype.toString = function () {
+        return "class B";
+    };
+    return B;
+}(Tagged(A)));
+var C = (function (_super) {
+    __extends(C, _super);
+    function C() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    C.prototype.toString = function () {
+        return "class C";
+    };
+    return C;
+}(A));
diff --git a/tests/baselines/reference/mixingApparentTypeOverrides.symbols b/tests/baselines/reference/mixingApparentTypeOverrides.symbols
new file mode 100644
index 00000000000..ea0adbb8acd
--- /dev/null
+++ b/tests/baselines/reference/mixingApparentTypeOverrides.symbols
@@ -0,0 +1,67 @@
+=== tests/cases/compiler/mixingApparentTypeOverrides.ts ===
+type Constructor<T> = new(...args: any[]) => T;
+>Constructor : Symbol(Constructor, Decl(mixingApparentTypeOverrides.ts, 0, 0))
+>T : Symbol(T, Decl(mixingApparentTypeOverrides.ts, 0, 17))
+>args : Symbol(args, Decl(mixingApparentTypeOverrides.ts, 0, 26))
+>T : Symbol(T, Decl(mixingApparentTypeOverrides.ts, 0, 17))
+
+function Tagged<T extends Constructor<{}>>(Base: T) {
+>Tagged : Symbol(Tagged, Decl(mixingApparentTypeOverrides.ts, 0, 47))
+>T : Symbol(T, Decl(mixingApparentTypeOverrides.ts, 1, 16))
+>Constructor : Symbol(Constructor, Decl(mixingApparentTypeOverrides.ts, 0, 0))
+>Base : Symbol(Base, Decl(mixingApparentTypeOverrides.ts, 1, 43))
+>T : Symbol(T, Decl(mixingApparentTypeOverrides.ts, 1, 16))
+
+  return class extends Base {
+>Base : Symbol(Base, Decl(mixingApparentTypeOverrides.ts, 1, 43))
+
+    _tag: string;
+>_tag : Symbol((Anonymous class)._tag, Decl(mixingApparentTypeOverrides.ts, 2, 29))
+
+    constructor(...args: any[]) {
+>args : Symbol(args, Decl(mixingApparentTypeOverrides.ts, 4, 16))
+
+      super(...args);
+>super : Symbol(T, Decl(mixingApparentTypeOverrides.ts, 1, 16))
+>args : Symbol(args, Decl(mixingApparentTypeOverrides.ts, 4, 16))
+
+      this._tag = "";
+>this._tag : Symbol((Anonymous class)._tag, Decl(mixingApparentTypeOverrides.ts, 2, 29))
+>this : Symbol((Anonymous class), Decl(mixingApparentTypeOverrides.ts, 2, 8))
+>_tag : Symbol((Anonymous class)._tag, Decl(mixingApparentTypeOverrides.ts, 2, 29))
+    }
+  };
+}
+
+class A {
+>A : Symbol(A, Decl(mixingApparentTypeOverrides.ts, 9, 1))
+
+  toString () {
+>toString : Symbol(A.toString, Decl(mixingApparentTypeOverrides.ts, 11, 9))
+
+    return "class A";
+  }
+}
+
+class B extends Tagged(A) {
+>B : Symbol(B, Decl(mixingApparentTypeOverrides.ts, 15, 1))
+>Tagged : Symbol(Tagged, Decl(mixingApparentTypeOverrides.ts, 0, 47))
+>A : Symbol(A, Decl(mixingApparentTypeOverrides.ts, 9, 1))
+
+  toString () { // Should not be an error
+>toString : Symbol(B.toString, Decl(mixingApparentTypeOverrides.ts, 17, 27))
+
+    return "class B";
+  }
+}
+
+class C extends A {
+>C : Symbol(C, Decl(mixingApparentTypeOverrides.ts, 21, 1))
+>A : Symbol(A, Decl(mixingApparentTypeOverrides.ts, 9, 1))
+
+  toString () { // Should not be an error
+>toString : Symbol(C.toString, Decl(mixingApparentTypeOverrides.ts, 23, 19))
+
+    return "class C";
+  }
+}
diff --git a/tests/baselines/reference/mixingApparentTypeOverrides.types b/tests/baselines/reference/mixingApparentTypeOverrides.types
new file mode 100644
index 00000000000..eae9c391a78
--- /dev/null
+++ b/tests/baselines/reference/mixingApparentTypeOverrides.types
@@ -0,0 +1,76 @@
+=== tests/cases/compiler/mixingApparentTypeOverrides.ts ===
+type Constructor<T> = new(...args: any[]) => T;
+>Constructor : Constructor<T>
+>T : T
+>args : any[]
+>T : T
+
+function Tagged<T extends Constructor<{}>>(Base: T) {
+>Tagged : <T extends Constructor<{}>>(Base: T) => { new (...args: any[]): (Anonymous class); prototype: Tagged<any>.(Anonymous class); } & T
+>T : T
+>Constructor : Constructor<T>
+>Base : T
+>T : T
+
+  return class extends Base {
+>class extends Base {    _tag: string;    constructor(...args: any[]) {      super(...args);      this._tag = "";    }  } : { new (...args: any[]): (Anonymous class); prototype: Tagged<any>.(Anonymous class); } & T
+>Base : {}
+
+    _tag: string;
+>_tag : string
+
+    constructor(...args: any[]) {
+>args : any[]
+
+      super(...args);
+>super(...args) : void
+>super : T
+>...args : any
+>args : any[]
+
+      this._tag = "";
+>this._tag = "" : ""
+>this._tag : string
+>this : this
+>_tag : string
+>"" : ""
+    }
+  };
+}
+
+class A {
+>A : A
+
+  toString () {
+>toString : () => string
+
+    return "class A";
+>"class A" : "class A"
+  }
+}
+
+class B extends Tagged(A) {
+>B : B
+>Tagged(A) : Tagged<typeof A>.(Anonymous class) & A
+>Tagged : <T extends Constructor<{}>>(Base: T) => { new (...args: any[]): (Anonymous class); prototype: Tagged<any>.(Anonymous class); } & T
+>A : typeof A
+
+  toString () { // Should not be an error
+>toString : () => string
+
+    return "class B";
+>"class B" : "class B"
+  }
+}
+
+class C extends A {
+>C : C
+>A : A
+
+  toString () { // Should not be an error
+>toString : () => string
+
+    return "class C";
+>"class C" : "class C"
+  }
+}
diff --git a/tests/baselines/reference/noUnusedLocals_selfReference.errors.txt b/tests/baselines/reference/noUnusedLocals_selfReference.errors.txt
new file mode 100644
index 00000000000..af40081e71c
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_selfReference.errors.txt
@@ -0,0 +1,28 @@
+tests/cases/compiler/noUnusedLocals_selfReference.ts(3,10): error TS6133: 'f' is declared but never used.
+tests/cases/compiler/noUnusedLocals_selfReference.ts(4,7): error TS6133: 'C' is declared but never used.
+tests/cases/compiler/noUnusedLocals_selfReference.ts(7,6): error TS6133: 'E' is declared but never used.
+
+
+==== tests/cases/compiler/noUnusedLocals_selfReference.ts (3 errors) ====
+    export {}; // Make this a module scope, so these are local variables.
+    
+    function f() { f; }
+             ~
+!!! error TS6133: 'f' is declared but never used.
+    class C {
+          ~
+!!! error TS6133: 'C' is declared but never used.
+        m() { C; }
+    }
+    enum E { A = 0, B = E.A }
+         ~
+!!! error TS6133: 'E' is declared but never used.
+    
+    // Does not detect mutual recursion.
+    function g() { D; }
+    class D { m() { g; } }
+    
+    // Does not work on private methods.
+    class P { private m() { this.m; } }
+    P;
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/noUnusedLocals_selfReference.js b/tests/baselines/reference/noUnusedLocals_selfReference.js
new file mode 100644
index 00000000000..74a39923d57
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_selfReference.js
@@ -0,0 +1,49 @@
+//// [noUnusedLocals_selfReference.ts]
+export {}; // Make this a module scope, so these are local variables.
+
+function f() { f; }
+class C {
+    m() { C; }
+}
+enum E { A = 0, B = E.A }
+
+// Does not detect mutual recursion.
+function g() { D; }
+class D { m() { g; } }
+
+// Does not work on private methods.
+class P { private m() { this.m; } }
+P;
+
+
+//// [noUnusedLocals_selfReference.js]
+"use strict";
+exports.__esModule = true;
+function f() { f; }
+var C = (function () {
+    function C() {
+    }
+    C.prototype.m = function () { C; };
+    return C;
+}());
+var E;
+(function (E) {
+    E[E["A"] = 0] = "A";
+    E[E["B"] = 0] = "B";
+})(E || (E = {}));
+// Does not detect mutual recursion.
+function g() { D; }
+var D = (function () {
+    function D() {
+    }
+    D.prototype.m = function () { g; };
+    return D;
+}());
+// Does not work on private methods.
+var P = (function () {
+    function P() {
+    }
+    P.prototype.m = function () { this.m; };
+    return P;
+}());
+P;
diff --git a/tests/baselines/reference/null.errors.txt b/tests/baselines/reference/null.errors.txt
index 6b05bfb94d1..ed6db12d99b 100644
--- a/tests/baselines/reference/null.errors.txt
+++ b/tests/baselines/reference/null.errors.txt
@@ -1,12 +1,12 @@
-tests/cases/compiler/null.ts(3,9): error TS2531: Object is possibly 'null'.
+tests/cases/compiler/null.ts(3,7): error TS2365: Operator '+' cannot be applied to types '3' and 'null'.
 
 
 ==== tests/cases/compiler/null.ts (1 errors) ====
     var x=null; 
     var y=3+x;  
     var z=3+null; 
-            ~~~~
-!!! error TS2531: Object is possibly 'null'.
+          ~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types '3' and 'null'.
     class C {
     }
     function f() {
diff --git a/tests/baselines/reference/operatorAddNullUndefined.errors.txt b/tests/baselines/reference/operatorAddNullUndefined.errors.txt
index 871ef3fc98f..c6a74080394 100644
--- a/tests/baselines/reference/operatorAddNullUndefined.errors.txt
+++ b/tests/baselines/reference/operatorAddNullUndefined.errors.txt
@@ -1,68 +1,56 @@
-tests/cases/compiler/operatorAddNullUndefined.ts(2,10): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(2,17): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(3,10): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(3,17): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(4,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(4,22): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(5,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(5,22): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(6,14): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(7,14): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(8,10): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(9,10): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(14,11): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(15,11): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/operatorAddNullUndefined.ts(16,17): error TS2531: Object is possibly 'null'.
-tests/cases/compiler/operatorAddNullUndefined.ts(17,17): error TS2532: Object is possibly 'undefined'.
+tests/cases/compiler/operatorAddNullUndefined.ts(2,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/compiler/operatorAddNullUndefined.ts(3,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/compiler/operatorAddNullUndefined.ts(4,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'null'.
+tests/cases/compiler/operatorAddNullUndefined.ts(5,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
+tests/cases/compiler/operatorAddNullUndefined.ts(6,10): error TS2365: Operator '+' cannot be applied to types '1' and 'null'.
+tests/cases/compiler/operatorAddNullUndefined.ts(7,10): error TS2365: Operator '+' cannot be applied to types '1' and 'undefined'.
+tests/cases/compiler/operatorAddNullUndefined.ts(8,10): error TS2365: Operator '+' cannot be applied to types 'null' and '1'.
+tests/cases/compiler/operatorAddNullUndefined.ts(9,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and '1'.
+tests/cases/compiler/operatorAddNullUndefined.ts(14,11): error TS2365: Operator '+' cannot be applied to types 'null' and 'E'.
+tests/cases/compiler/operatorAddNullUndefined.ts(15,11): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E'.
+tests/cases/compiler/operatorAddNullUndefined.ts(16,11): error TS2365: Operator '+' cannot be applied to types 'E' and 'null'.
+tests/cases/compiler/operatorAddNullUndefined.ts(17,11): error TS2365: Operator '+' cannot be applied to types 'E' and 'undefined'.
 
 
-==== tests/cases/compiler/operatorAddNullUndefined.ts (16 errors) ====
+==== tests/cases/compiler/operatorAddNullUndefined.ts (12 errors) ====
     enum E { x }
     var x1 = null + null;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var x2 = null + undefined;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var x3 = undefined + null;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                         ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'null'.
     var x4 = undefined + undefined;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                         ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     var x5 = 1 + null;
-                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types '1' and 'null'.
     var x6 = 1 + undefined;
-                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types '1' and 'undefined'.
     var x7 = null + 1;
-             ~~~~
-!!! error TS2531: Object is possibly 'null'.
+             ~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and '1'.
     var x8 = undefined + 1;
-             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+             ~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and '1'.
     var x9 = "test" + null;
     var x10 = "test" + undefined;
     var x11 = null + "test";
     var x12 = undefined + "test";
     var x13 = null + E.x
-              ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'E'.
     var x14 = undefined + E.x
-              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+              ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'E'.
     var x15 = E.x + null
-                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+              ~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E' and 'null'.
     var x16 = E.x + undefined
-                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
\ No newline at end of file
+              ~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'E' and 'undefined'.
\ No newline at end of file
diff --git a/tests/baselines/reference/plusOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/plusOperatorWithAnyOtherType.errors.txt
index d693aaa17d9..561215bbd95 100644
--- a/tests/baselines/reference/plusOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/plusOperatorWithAnyOtherType.errors.txt
@@ -1,15 +1,12 @@
 tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(34,24): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(35,24): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(46,26): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(46,33): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(47,26): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(47,33): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(48,26): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(48,38): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(46,26): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(47,26): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(48,26): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts(54,1): error TS2695: Left side of comma operator is unused and has no side effects.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts (9 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWithAnyOtherType.ts (6 errors) ====
     // + operator on any type
     
     var ANY: any;
@@ -60,20 +57,14 @@ tests/cases/conformance/expressions/unaryOperators/plusOperator/plusOperatorWith
     var ResultIsNumber15 = +A.foo();
     var ResultIsNumber16 = +(ANY + ANY1);
     var ResultIsNumber17 = +(null + undefined);
-                             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                    ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                             ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsNumber18 = +(null + null);
-                             ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                    ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                             ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsNumber19 = +(undefined + undefined);
-                             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                         ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                             ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     
     // miss assignment operators
     +ANY;
diff --git a/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/amd/nodeModulesMaxDepthExceeded.errors.txt b/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/amd/nodeModulesMaxDepthExceeded.errors.txt
index a1b170ce665..bd2dd6231f3 100644
--- a/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/amd/nodeModulesMaxDepthExceeded.errors.txt
+++ b/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/amd/nodeModulesMaxDepthExceeded.errors.txt
@@ -9,7 +9,7 @@ maxDepthExceeded/root.ts(4,4): error TS2540: Cannot assign to 'rel' because it i
         "maxNodeModuleJsDepth": 1, // Note: Module m1 is already included as a root file
         "outDir": "built"
       },
-      "include": ["**/*"],
+      "include": ["**/*", "node_modules/**/*"],
       "exclude": ["node_modules/m2/**/*"]
     }
     
diff --git a/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/node/nodeModulesMaxDepthExceeded.errors.txt b/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/node/nodeModulesMaxDepthExceeded.errors.txt
index a1b170ce665..bd2dd6231f3 100644
--- a/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/node/nodeModulesMaxDepthExceeded.errors.txt
+++ b/tests/baselines/reference/project/nodeModulesMaxDepthExceeded/node/nodeModulesMaxDepthExceeded.errors.txt
@@ -9,7 +9,7 @@ maxDepthExceeded/root.ts(4,4): error TS2540: Cannot assign to 'rel' because it i
         "maxNodeModuleJsDepth": 1, // Note: Module m1 is already included as a root file
         "outDir": "built"
       },
-      "include": ["**/*"],
+      "include": ["**/*", "node_modules/**/*"],
       "exclude": ["node_modules/m2/**/*"]
     }
     
diff --git a/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.js b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.js
new file mode 100644
index 00000000000..c49924191e5
--- /dev/null
+++ b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.js
@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/syntheticDefaultExportsWithDynamicImports.ts] ////
+
+//// [index.d.ts]
+declare function packageExport(x: number): string;
+export = packageExport;
+
+//// [index.ts]
+import("package").then(({default: foo}) => foo(42));
+
+//// [index.js]
+System.register([], function (exports_1, context_1) {
+    var __moduleName = context_1 && context_1.id;
+    return {
+        setters: [],
+        execute: function () {
+            context_1.import("package").then(({ default: foo }) => foo(42));
+        }
+    };
+});
diff --git a/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.symbols b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.symbols
new file mode 100644
index 00000000000..85019711153
--- /dev/null
+++ b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.symbols
@@ -0,0 +1,17 @@
+=== tests/cases/compiler/node_modules/package/index.d.ts ===
+declare function packageExport(x: number): string;
+>packageExport : Symbol(packageExport, Decl(index.d.ts, 0, 0))
+>x : Symbol(x, Decl(index.d.ts, 0, 31))
+
+export = packageExport;
+>packageExport : Symbol(packageExport, Decl(index.d.ts, 0, 0))
+
+=== tests/cases/compiler/index.ts ===
+import("package").then(({default: foo}) => foo(42));
+>import("package").then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>"package" : Symbol("tests/cases/compiler/node_modules/package/index", Decl(index.d.ts, 0, 0))
+>then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
+>default : Symbol(default)
+>foo : Symbol(foo, Decl(index.ts, 0, 25))
+>foo : Symbol(foo, Decl(index.ts, 0, 25))
+
diff --git a/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.types b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.types
new file mode 100644
index 00000000000..1c38ecc466c
--- /dev/null
+++ b/tests/baselines/reference/syntheticDefaultExportsWithDynamicImports.types
@@ -0,0 +1,22 @@
+=== tests/cases/compiler/node_modules/package/index.d.ts ===
+declare function packageExport(x: number): string;
+>packageExport : (x: number) => string
+>x : number
+
+export = packageExport;
+>packageExport : (x: number) => string
+
+=== tests/cases/compiler/index.ts ===
+import("package").then(({default: foo}) => foo(42));
+>import("package").then(({default: foo}) => foo(42)) : Promise<string>
+>import("package").then : <TResult1 = ((x: number) => string) & { default: (x: number) => string; }, TResult2 = never>(onfulfilled?: (value: ((x: number) => string) & { default: (x: number) => string; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>import("package") : Promise<((x: number) => string) & { default: (x: number) => string; }>
+>"package" : "package"
+>then : <TResult1 = ((x: number) => string) & { default: (x: number) => string; }, TResult2 = never>(onfulfilled?: (value: ((x: number) => string) & { default: (x: number) => string; }) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>
+>({default: foo}) => foo(42) : ({ default: foo }: ((x: number) => string) & { default: (x: number) => string; }) => string
+>default : any
+>foo : (x: number) => string
+>foo(42) : string
+>foo : (x: number) => string
+>42 : 42
+
diff --git a/tests/baselines/reference/tryStatements.js b/tests/baselines/reference/tryStatements.js
index 723014c1b52..64fe2cf06a7 100644
--- a/tests/baselines/reference/tryStatements.js
+++ b/tests/baselines/reference/tryStatements.js
@@ -1,26 +1,47 @@
 //// [tryStatements.ts]
 function fn() {
-    try {
+    try { } catch { }
 
-    } catch (x) {
-        var x: any;
+    try { } catch { 
+        try { } catch { 
+            try { } catch { }
+        }
+        try { } catch { }
     }
 
+    try { } catch (x) { var x: any; }
+
     try { } finally { }
 
-    try { }catch(z){ } finally { }
+    try { } catch { } finally { }
+
+    try { } catch (z) { } finally { }
 }
 
 //// [tryStatements.js]
 function fn() {
-    try {
+    try { }
+    catch (_a) { }
+    try { }
+    catch (_b) {
+        try { }
+        catch (_c) {
+            try { }
+            catch (_d) { }
+        }
+        try { }
+        catch (_e) { }
     }
+    try { }
     catch (x) {
         var x;
     }
     try { }
     finally { }
     try { }
+    catch (_f) { }
+    finally { }
+    try { }
     catch (z) { }
     finally { }
 }
diff --git a/tests/baselines/reference/tryStatements.symbols b/tests/baselines/reference/tryStatements.symbols
index 945ca2d9d88..69e9918a98b 100644
--- a/tests/baselines/reference/tryStatements.symbols
+++ b/tests/baselines/reference/tryStatements.symbols
@@ -2,17 +2,23 @@
 function fn() {
 >fn : Symbol(fn, Decl(tryStatements.ts, 0, 0))
 
-    try {
+    try { } catch { }
 
-    } catch (x) {
->x : Symbol(x, Decl(tryStatements.ts, 3, 13))
-
-        var x: any;
->x : Symbol(x, Decl(tryStatements.ts, 4, 11))
+    try { } catch { 
+        try { } catch { 
+            try { } catch { }
+        }
+        try { } catch { }
     }
 
+    try { } catch (x) { var x: any; }
+>x : Symbol(x, Decl(tryStatements.ts, 10, 19))
+>x : Symbol(x, Decl(tryStatements.ts, 10, 27))
+
     try { } finally { }
 
-    try { }catch(z){ } finally { }
->z : Symbol(z, Decl(tryStatements.ts, 9, 17))
+    try { } catch { } finally { }
+
+    try { } catch (z) { } finally { }
+>z : Symbol(z, Decl(tryStatements.ts, 16, 19))
 }
diff --git a/tests/baselines/reference/tryStatements.types b/tests/baselines/reference/tryStatements.types
index 07bc3997d83..05c02568135 100644
--- a/tests/baselines/reference/tryStatements.types
+++ b/tests/baselines/reference/tryStatements.types
@@ -2,17 +2,23 @@
 function fn() {
 >fn : () => void
 
-    try {
+    try { } catch { }
 
-    } catch (x) {
->x : any
-
-        var x: any;
->x : any
+    try { } catch { 
+        try { } catch { 
+            try { } catch { }
+        }
+        try { } catch { }
     }
 
+    try { } catch (x) { var x: any; }
+>x : any
+>x : any
+
     try { } finally { }
 
-    try { }catch(z){ } finally { }
+    try { } catch { } finally { }
+
+    try { } catch (z) { } finally { }
 >z : any
 }
diff --git a/tests/baselines/reference/typeParameterExtendsPrimitive.js b/tests/baselines/reference/typeParameterExtendsPrimitive.js
new file mode 100644
index 00000000000..1774db19f6e
--- /dev/null
+++ b/tests/baselines/reference/typeParameterExtendsPrimitive.js
@@ -0,0 +1,51 @@
+//// [typeParameterExtendsPrimitive.ts]
+// #14473
+function f<T extends number>() {
+    var t: T;
+    var v = {
+        [t]: 0
+    }
+    return t + t;
+}
+
+// #15501
+interface I { x: number }
+type IdMap<T> = { [P in keyof T]: T[P] };
+function g<T extends I>(i: IdMap<T>) {
+    const n: number = i.x;
+    return i.x * 2;
+}
+
+// #17069
+function h<T extends Record<K, number>, K extends string>(array: T[], prop: K): number {
+    let result = 0;
+    for (const v of array) {
+        result += v[prop];
+    }
+    return result;
+}
+
+
+//// [typeParameterExtendsPrimitive.js]
+// #14473
+function f() {
+    var t;
+    var v = (_a = {},
+        _a[t] = 0,
+        _a);
+    return t + t;
+    var _a;
+}
+function g(i) {
+    var n = i.x;
+    return i.x * 2;
+}
+// #17069
+function h(array, prop) {
+    var result = 0;
+    for (var _i = 0, array_1 = array; _i < array_1.length; _i++) {
+        var v = array_1[_i];
+        result += v[prop];
+    }
+    return result;
+}
diff --git a/tests/baselines/reference/typeParameterExtendsPrimitive.symbols b/tests/baselines/reference/typeParameterExtendsPrimitive.symbols
new file mode 100644
index 00000000000..acac75272ac
--- /dev/null
+++ b/tests/baselines/reference/typeParameterExtendsPrimitive.symbols
@@ -0,0 +1,82 @@
+=== tests/cases/compiler/typeParameterExtendsPrimitive.ts ===
+// #14473
+function f<T extends number>() {
+>f : Symbol(f, Decl(typeParameterExtendsPrimitive.ts, 0, 0))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 1, 11))
+
+    var t: T;
+>t : Symbol(t, Decl(typeParameterExtendsPrimitive.ts, 2, 7))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 1, 11))
+
+    var v = {
+>v : Symbol(v, Decl(typeParameterExtendsPrimitive.ts, 3, 7))
+
+        [t]: 0
+>t : Symbol(t, Decl(typeParameterExtendsPrimitive.ts, 2, 7))
+    }
+    return t + t;
+>t : Symbol(t, Decl(typeParameterExtendsPrimitive.ts, 2, 7))
+>t : Symbol(t, Decl(typeParameterExtendsPrimitive.ts, 2, 7))
+}
+
+// #15501
+interface I { x: number }
+>I : Symbol(I, Decl(typeParameterExtendsPrimitive.ts, 7, 1))
+>x : Symbol(I.x, Decl(typeParameterExtendsPrimitive.ts, 10, 13))
+
+type IdMap<T> = { [P in keyof T]: T[P] };
+>IdMap : Symbol(IdMap, Decl(typeParameterExtendsPrimitive.ts, 10, 25))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 11, 11))
+>P : Symbol(P, Decl(typeParameterExtendsPrimitive.ts, 11, 19))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 11, 11))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 11, 11))
+>P : Symbol(P, Decl(typeParameterExtendsPrimitive.ts, 11, 19))
+
+function g<T extends I>(i: IdMap<T>) {
+>g : Symbol(g, Decl(typeParameterExtendsPrimitive.ts, 11, 41))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 12, 11))
+>I : Symbol(I, Decl(typeParameterExtendsPrimitive.ts, 7, 1))
+>i : Symbol(i, Decl(typeParameterExtendsPrimitive.ts, 12, 24))
+>IdMap : Symbol(IdMap, Decl(typeParameterExtendsPrimitive.ts, 10, 25))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 12, 11))
+
+    const n: number = i.x;
+>n : Symbol(n, Decl(typeParameterExtendsPrimitive.ts, 13, 9))
+>i.x : Symbol(x, Decl(typeParameterExtendsPrimitive.ts, 10, 13))
+>i : Symbol(i, Decl(typeParameterExtendsPrimitive.ts, 12, 24))
+>x : Symbol(x, Decl(typeParameterExtendsPrimitive.ts, 10, 13))
+
+    return i.x * 2;
+>i.x : Symbol(x, Decl(typeParameterExtendsPrimitive.ts, 10, 13))
+>i : Symbol(i, Decl(typeParameterExtendsPrimitive.ts, 12, 24))
+>x : Symbol(x, Decl(typeParameterExtendsPrimitive.ts, 10, 13))
+}
+
+// #17069
+function h<T extends Record<K, number>, K extends string>(array: T[], prop: K): number {
+>h : Symbol(h, Decl(typeParameterExtendsPrimitive.ts, 15, 1))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 18, 11))
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(typeParameterExtendsPrimitive.ts, 18, 39))
+>K : Symbol(K, Decl(typeParameterExtendsPrimitive.ts, 18, 39))
+>array : Symbol(array, Decl(typeParameterExtendsPrimitive.ts, 18, 58))
+>T : Symbol(T, Decl(typeParameterExtendsPrimitive.ts, 18, 11))
+>prop : Symbol(prop, Decl(typeParameterExtendsPrimitive.ts, 18, 69))
+>K : Symbol(K, Decl(typeParameterExtendsPrimitive.ts, 18, 39))
+
+    let result = 0;
+>result : Symbol(result, Decl(typeParameterExtendsPrimitive.ts, 19, 7))
+
+    for (const v of array) {
+>v : Symbol(v, Decl(typeParameterExtendsPrimitive.ts, 20, 14))
+>array : Symbol(array, Decl(typeParameterExtendsPrimitive.ts, 18, 58))
+
+        result += v[prop];
+>result : Symbol(result, Decl(typeParameterExtendsPrimitive.ts, 19, 7))
+>v : Symbol(v, Decl(typeParameterExtendsPrimitive.ts, 20, 14))
+>prop : Symbol(prop, Decl(typeParameterExtendsPrimitive.ts, 18, 69))
+    }
+    return result;
+>result : Symbol(result, Decl(typeParameterExtendsPrimitive.ts, 19, 7))
+}
+
diff --git a/tests/baselines/reference/typeParameterExtendsPrimitive.types b/tests/baselines/reference/typeParameterExtendsPrimitive.types
new file mode 100644
index 00000000000..1e8eb7f40e0
--- /dev/null
+++ b/tests/baselines/reference/typeParameterExtendsPrimitive.types
@@ -0,0 +1,90 @@
+=== tests/cases/compiler/typeParameterExtendsPrimitive.ts ===
+// #14473
+function f<T extends number>() {
+>f : <T extends number>() => number
+>T : T
+
+    var t: T;
+>t : T
+>T : T
+
+    var v = {
+>v : { [x: number]: number; }
+>{        [t]: 0    } : { [x: number]: number; }
+
+        [t]: 0
+>t : T
+>0 : 0
+    }
+    return t + t;
+>t + t : number
+>t : T
+>t : T
+}
+
+// #15501
+interface I { x: number }
+>I : I
+>x : number
+
+type IdMap<T> = { [P in keyof T]: T[P] };
+>IdMap : IdMap<T>
+>T : T
+>P : P
+>T : T
+>T : T
+>P : P
+
+function g<T extends I>(i: IdMap<T>) {
+>g : <T extends I>(i: IdMap<T>) => number
+>T : T
+>I : I
+>i : IdMap<T>
+>IdMap : IdMap<T>
+>T : T
+
+    const n: number = i.x;
+>n : number
+>i.x : T["x"]
+>i : IdMap<T>
+>x : T["x"]
+
+    return i.x * 2;
+>i.x * 2 : number
+>i.x : T["x"]
+>i : IdMap<T>
+>x : T["x"]
+>2 : 2
+}
+
+// #17069
+function h<T extends Record<K, number>, K extends string>(array: T[], prop: K): number {
+>h : <T extends Record<K, number>, K extends string>(array: T[], prop: K) => number
+>T : T
+>Record : Record<K, T>
+>K : K
+>K : K
+>array : T[]
+>T : T
+>prop : K
+>K : K
+
+    let result = 0;
+>result : number
+>0 : 0
+
+    for (const v of array) {
+>v : T
+>array : T[]
+
+        result += v[prop];
+>result += v[prop] : number
+>result : number
+>v[prop] : T[K]
+>v : T
+>prop : K
+    }
+    return result;
+>result : number
+}
+
diff --git a/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
index 3680b1be60f..9357cf4e4cc 100644
--- a/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
@@ -1,9 +1,6 @@
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(46,32): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(46,39): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(47,32): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(47,39): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(48,32): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(48,44): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(46,32): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(47,32): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(48,32): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(58,1): error TS2695: Left side of comma operator is unused and has no side effects.
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(68,1): error TS7028: Unused label.
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(69,1): error TS7028: Unused label.
@@ -14,7 +11,7 @@ tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperator
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(74,1): error TS7028: Unused label.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts (14 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts (11 errors) ====
     // typeof  operator on any type
     
     var ANY: any;
@@ -61,20 +58,14 @@ tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperator
     var ResultIsString15 = typeof A.foo();
     var ResultIsString16 = typeof (ANY + ANY1);
     var ResultIsString17 = typeof (null + undefined);
-                                   ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                                   ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsString18 = typeof (null + null);
-                                   ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                          ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                                   ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsString19 = typeof (undefined + undefined);
-                                   ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                               ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                                   ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     
     // multiple typeof  operators
     var ResultIsString20 = typeof typeof ANY;
diff --git a/tests/baselines/reference/unusedLocalsAndParametersTypeAliases2.errors.txt b/tests/baselines/reference/unusedLocalsAndParametersTypeAliases2.errors.txt
index 528ca9f9e73..e5c6f476480 100644
--- a/tests/baselines/reference/unusedLocalsAndParametersTypeAliases2.errors.txt
+++ b/tests/baselines/reference/unusedLocalsAndParametersTypeAliases2.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts(2,6): error TS6133: 'handler1' is declared but never used.
+tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts(5,10): error TS6133: 'foo' is declared but never used.
 tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts(6,10): error TS6133: 'handler2' is declared but never used.
 
 
-==== tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts (2 errors) ====
+==== tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts (3 errors) ====
     // unused
     type handler1 = () => void;
          ~~~~~~~~
@@ -10,6 +11,8 @@ tests/cases/compiler/unusedLocalsAndParametersTypeAliases2.ts(6,10): error TS613
     
     
     function foo() {
+             ~~~
+!!! error TS6133: 'foo' is declared but never used.
         type handler2 = () => void;
              ~~~~~~~~
 !!! error TS6133: 'handler2' is declared but never used.
diff --git a/tests/baselines/reference/voidOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/voidOperatorWithAnyOtherType.errors.txt
index 5867a7ad6f5..7230f90c4f3 100644
--- a/tests/baselines/reference/voidOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/voidOperatorWithAnyOtherType.errors.txt
@@ -1,12 +1,9 @@
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(46,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(46,34): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(47,27): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(47,34): error TS2531: Object is possibly 'null'.
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(48,27): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(48,39): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(46,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
+tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(47,27): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
+tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts(48,27): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts (6 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWithAnyOtherType.ts (3 errors) ====
     // void  operator on any type
     
     var ANY: any;
@@ -53,20 +50,14 @@ tests/cases/conformance/expressions/unaryOperators/voidOperator/voidOperatorWith
     var ResultIsAny15 = void A.foo();
     var ResultIsAny16 = void (ANY + ANY1);
     var ResultIsAny17 = void (null + undefined);
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'undefined'.
     var ResultIsAny18 = void (null + null);
-                              ~~~~
-!!! error TS2531: Object is possibly 'null'.
-                                     ~~~~
-!!! error TS2531: Object is possibly 'null'.
+                              ~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
     var ResultIsAny19 = void (undefined + undefined);
-                              ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
-                                          ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+                              ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
     
     // multiple void  operators
     var ResultIsAny20 = void void ANY;
diff --git a/tests/baselines/reference/weakType.errors.txt b/tests/baselines/reference/weakType.errors.txt
index 441ef70ac16..ffc1d237593 100644
--- a/tests/baselines/reference/weakType.errors.txt
+++ b/tests/baselines/reference/weakType.errors.txt
@@ -1,14 +1,17 @@
-tests/cases/compiler/weakType.ts(16,13): error TS2559: Type '12' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(17,13): error TS2559: Type '"completely wrong"' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(18,13): error TS2559: Type 'false' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(35,18): error TS2559: Type '{ error?: number; }' has no properties in common with type 'ChangeOptions'.
-tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak & Spoiler'.
+tests/cases/compiler/weakType.ts(15,13): error TS2560: Value of type '() => { timeout: number; }' has no properties in common with type 'Settings'. Did you mean to call it?
+tests/cases/compiler/weakType.ts(16,13): error TS2560: Value of type '() => { timeout: number; }' has no properties in common with type 'Settings'. Did you mean to call it?
+tests/cases/compiler/weakType.ts(17,13): error TS2560: Value of type 'CtorOnly' has no properties in common with type 'Settings'. Did you mean to call it?
+tests/cases/compiler/weakType.ts(18,13): error TS2559: Type '12' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(19,13): error TS2559: Type '"completely wrong"' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(20,13): error TS2559: Type 'false' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(37,18): error TS2559: Type '{ error?: number; }' has no properties in common with type 'ChangeOptions'.
+tests/cases/compiler/weakType.ts(62,5): error TS2322: Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak & Spoiler'.
   Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak'.
     Types of property 'properties' are incompatible.
       Type '{ wrong: string; }' has no properties in common with type '{ b?: number; }'.
 
 
-==== tests/cases/compiler/weakType.ts (5 errors) ====
+==== tests/cases/compiler/weakType.ts (8 errors) ====
     interface Settings {
         timeout?: number;
         onError?(): void;
@@ -17,13 +20,21 @@ tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wron
     function getDefaultSettings() {
         return { timeout: 1000 };
     }
+    interface CtorOnly {
+        new(s: string): { timeout: 1000 }
+    }
     
     function doSomething(settings: Settings) { /* ... */ }
     // forgot to call `getDefaultSettings`
-    // but it is not caught because we don't check for call signatures
     doSomething(getDefaultSettings);
-    // same for arrow expressions:
-    doSomething(() => { });
+                ~~~~~~~~~~~~~~~~~~
+!!! error TS2560: Value of type '() => { timeout: number; }' has no properties in common with type 'Settings'. Did you mean to call it?
+    doSomething(() => ({ timeout: 1000 }));
+                ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2560: Value of type '() => { timeout: number; }' has no properties in common with type 'Settings'. Did you mean to call it?
+    doSomething(null as CtorOnly);
+                ~~~~~~~~~~~~~~~~
+!!! error TS2560: Value of type 'CtorOnly' has no properties in common with type 'Settings'. Did you mean to call it?
     doSomething(12);
                 ~~
 !!! error TS2559: Type '12' has no properties in common with type 'Settings'.
@@ -82,4 +93,5 @@ tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wron
 !!! error TS2322:   Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak'.
 !!! error TS2322:     Types of property 'properties' are incompatible.
 !!! error TS2322:       Type '{ wrong: string; }' has no properties in common with type '{ b?: number; }'.
+    
     
\ No newline at end of file
diff --git a/tests/baselines/reference/weakType.js b/tests/baselines/reference/weakType.js
index 5637271ccec..2a1dc4ca0e4 100644
--- a/tests/baselines/reference/weakType.js
+++ b/tests/baselines/reference/weakType.js
@@ -7,13 +7,15 @@ interface Settings {
 function getDefaultSettings() {
     return { timeout: 1000 };
 }
+interface CtorOnly {
+    new(s: string): { timeout: 1000 }
+}
 
 function doSomething(settings: Settings) { /* ... */ }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
-doSomething(() => { });
+doSomething(() => ({ timeout: 1000 }));
+doSomething(null as CtorOnly);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);
@@ -59,6 +61,7 @@ declare let unknown: {
     }
 }
 let weak: Weak & Spoiler = unknown
+
 
 
 //// [weakType.js]
@@ -67,10 +70,9 @@ function getDefaultSettings() {
 }
 function doSomething(settings) { }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
-doSomething(function () { });
+doSomething(function () { return ({ timeout: 1000 }); });
+doSomething(null);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);
diff --git a/tests/cases/compiler/checkTypePredicateForRedundantProperties.ts b/tests/cases/compiler/checkTypePredicateForRedundantProperties.ts
new file mode 100644
index 00000000000..35222f1e9db
--- /dev/null
+++ b/tests/cases/compiler/checkTypePredicateForRedundantProperties.ts
@@ -0,0 +1,3 @@
+function addProp2(x: any): x is { a: string; a: string; } {
+    return true;
+}
diff --git a/tests/cases/compiler/jsdocCastCommentEmit.ts b/tests/cases/compiler/jsdocCastCommentEmit.ts
new file mode 100644
index 00000000000..5e7230bd049
--- /dev/null
+++ b/tests/cases/compiler/jsdocCastCommentEmit.ts
@@ -0,0 +1,7 @@
+// allowJs: true
+// checkJs: true
+// outDir: out/
+// filename: input.js
+function f() {
+    return /* @type {number} */ 42;
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/mixingApparentTypeOverrides.ts b/tests/cases/compiler/mixingApparentTypeOverrides.ts
new file mode 100644
index 00000000000..5d68c58d461
--- /dev/null
+++ b/tests/cases/compiler/mixingApparentTypeOverrides.ts
@@ -0,0 +1,28 @@
+type Constructor<T> = new(...args: any[]) => T;
+function Tagged<T extends Constructor<{}>>(Base: T) {
+  return class extends Base {
+    _tag: string;
+    constructor(...args: any[]) {
+      super(...args);
+      this._tag = "";
+    }
+  };
+}
+
+class A {
+  toString () {
+    return "class A";
+  }
+}
+
+class B extends Tagged(A) {
+  toString () { // Should not be an error
+    return "class B";
+  }
+}
+
+class C extends A {
+  toString () { // Should not be an error
+    return "class C";
+  }
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/noUnusedLocals_selfReference.ts b/tests/cases/compiler/noUnusedLocals_selfReference.ts
new file mode 100644
index 00000000000..8eb528743c0
--- /dev/null
+++ b/tests/cases/compiler/noUnusedLocals_selfReference.ts
@@ -0,0 +1,17 @@
+// @noUnusedLocals: true
+
+export {}; // Make this a module scope, so these are local variables.
+
+function f() { f; }
+class C {
+    m() { C; }
+}
+enum E { A = 0, B = E.A }
+
+// Does not detect mutual recursion.
+function g() { D; }
+class D { m() { g; } }
+
+// Does not work on private methods.
+class P { private m() { this.m; } }
+P;
diff --git a/tests/cases/compiler/syntheticDefaultExportsWithDynamicImports.ts b/tests/cases/compiler/syntheticDefaultExportsWithDynamicImports.ts
new file mode 100644
index 00000000000..07f08d03185
--- /dev/null
+++ b/tests/cases/compiler/syntheticDefaultExportsWithDynamicImports.ts
@@ -0,0 +1,9 @@
+// @module: system
+// @target: es6
+// @moduleResolution: node
+// @filename: node_modules/package/index.d.ts
+declare function packageExport(x: number): string;
+export = packageExport;
+
+// @filename: index.ts
+import("package").then(({default: foo}) => foo(42));
\ No newline at end of file
diff --git a/tests/cases/compiler/typeParameterExtendsPrimitive.ts b/tests/cases/compiler/typeParameterExtendsPrimitive.ts
new file mode 100644
index 00000000000..b94a44b4660
--- /dev/null
+++ b/tests/cases/compiler/typeParameterExtendsPrimitive.ts
@@ -0,0 +1,25 @@
+// #14473
+function f<T extends number>() {
+    var t: T;
+    var v = {
+        [t]: 0
+    }
+    return t + t;
+}
+
+// #15501
+interface I { x: number }
+type IdMap<T> = { [P in keyof T]: T[P] };
+function g<T extends I>(i: IdMap<T>) {
+    const n: number = i.x;
+    return i.x * 2;
+}
+
+// #17069
+function h<T extends Record<K, number>, K extends string>(array: T[], prop: K): number {
+    let result = 0;
+    for (const v of array) {
+        result += v[prop];
+    }
+    return result;
+}
diff --git a/tests/cases/compiler/weakType.ts b/tests/cases/compiler/weakType.ts
index ffe51205e53..08c9d95e672 100644
--- a/tests/cases/compiler/weakType.ts
+++ b/tests/cases/compiler/weakType.ts
@@ -6,13 +6,15 @@ interface Settings {
 function getDefaultSettings() {
     return { timeout: 1000 };
 }
+interface CtorOnly {
+    new(s: string): { timeout: 1000 }
+}
 
 function doSomething(settings: Settings) { /* ... */ }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
-doSomething(() => { });
+doSomething(() => ({ timeout: 1000 }));
+doSomething(null as CtorOnly);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);
@@ -58,3 +60,4 @@ declare let unknown: {
     }
 }
 let weak: Weak & Spoiler = unknown
+
diff --git a/tests/cases/conformance/emitter/esnext/noCatchBinding/emitter.noCatchBinding.esnext.ts b/tests/cases/conformance/emitter/esnext/noCatchBinding/emitter.noCatchBinding.esnext.ts
new file mode 100644
index 00000000000..8e87b3c8c8f
--- /dev/null
+++ b/tests/cases/conformance/emitter/esnext/noCatchBinding/emitter.noCatchBinding.esnext.ts
@@ -0,0 +1,8 @@
+// @target: esnext
+function f() {
+    try { } catch { }
+    try { } catch { 
+        try { } catch { }
+    }
+    try { } catch { } finally { }
+}
\ No newline at end of file
diff --git a/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES5.ts b/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES5.ts
new file mode 100644
index 00000000000..1d467245fb2
--- /dev/null
+++ b/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES5.ts
@@ -0,0 +1,8 @@
+function f<T, K extends keyof T>() {
+    var t: T;
+    var k: K;
+    var v = {
+        [t]: 0,
+        [k]: 1
+    };
+}
diff --git a/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES6.ts b/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES6.ts
new file mode 100644
index 00000000000..ca209996c4c
--- /dev/null
+++ b/tests/cases/conformance/es6/computedProperties/computedPropertyNames51_ES6.ts
@@ -0,0 +1,9 @@
+// @target: es6
+function f<T, K extends keyof T>() {
+    var t: T;
+    var k: K;
+    var v = {
+        [t]: 0,
+        [k]: 1
+    };
+}
diff --git a/tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts b/tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts
index 6937e509845..7fb1b135c90 100644
--- a/tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts
+++ b/tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts
@@ -1,28 +1,20 @@
 function fn() {
-    try {
-    } catch { // syntax error, missing '(x)'
-    }
-
     catch(x) { } // error missing try
 
-    finally{ } // potential error; can be absorbed by the 'catch'
+    finally { } // potential error; can be absorbed by the 'catch'
+
+    try { }; // error missing finally
 }
 
 function fn2() {
     finally { } // error missing try
     catch (x) { } // error missing try
+    
+    try { } finally { } // statement is here, so the 'catch' clause above doesn't absorb errors from the 'finally' clause below
 
-    // no error
-    try {
-    }
-    finally {
-    }
+    finally { } // error missing try
+    
+    catch (x) { } // error missing try
 
-    // error missing try
-    finally {
-    }
-
-    // error missing try
-    catch (x) {
-    }
+    try { } catch () { } // error missing catch binding
 }
\ No newline at end of file
diff --git a/tests/cases/conformance/statements/tryStatements/tryStatements.ts b/tests/cases/conformance/statements/tryStatements/tryStatements.ts
index 691c046d6d1..0a47ba7a94b 100644
--- a/tests/cases/conformance/statements/tryStatements/tryStatements.ts
+++ b/tests/cases/conformance/statements/tryStatements/tryStatements.ts
@@ -1,11 +1,19 @@
-function fn() {
-    try {
 
-    } catch (x) {
-        var x: any;
+function fn() {
+    try { } catch { }
+
+    try { } catch { 
+        try { } catch { 
+            try { } catch { }
+        }
+        try { } catch { }
     }
 
+    try { } catch (x) { var x: any; }
+
     try { } finally { }
 
-    try { }catch(z){ } finally { }
+    try { } catch { } finally { }
+
+    try { } catch (z) { } finally { }
 }
\ No newline at end of file
diff --git a/tests/cases/fourslash/formattingSpaceBetweenParent.ts b/tests/cases/fourslash/formattingSpaceBetweenParent.ts
new file mode 100644
index 00000000000..60ec632f59c
--- /dev/null
+++ b/tests/cases/fourslash/formattingSpaceBetweenParent.ts
@@ -0,0 +1,14 @@
+/// <reference path='fourslash.ts' />
+
+/////*1*/foo(() => 1);
+/////*2*/foo(1);
+/////*3*/if((true)){}
+
+format.setOption("InsertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis", true);
+format.document();
+goTo.marker("1");
+verify.currentLineContentIs("foo( () => 1 );");
+goTo.marker("2");
+verify.currentLineContentIs("foo( 1 );");
+goTo.marker("3");
+verify.currentLineContentIs("if ( ( true ) ) { }");
diff --git a/tests/cases/projects/NodeModulesSearch/maxDepthExceeded/tsconfig.json b/tests/cases/projects/NodeModulesSearch/maxDepthExceeded/tsconfig.json
index 52633bb5a98..b2ee28482ba 100644
--- a/tests/cases/projects/NodeModulesSearch/maxDepthExceeded/tsconfig.json
+++ b/tests/cases/projects/NodeModulesSearch/maxDepthExceeded/tsconfig.json
@@ -4,6 +4,6 @@
     "maxNodeModuleJsDepth": 1, // Note: Module m1 is already included as a root file
     "outDir": "built"
   },
-  "include": ["**/*"],
+  "include": ["**/*", "node_modules/**/*"],
   "exclude": ["node_modules/m2/**/*"]
 }
diff --git a/tests/webTestServer.ts b/tests/webTestServer.ts
index abfd71a8fff..20228f9a741 100644
--- a/tests/webTestServer.ts
+++ b/tests/webTestServer.ts
@@ -125,22 +125,6 @@ function dir(dirPath: string, spec?: string, options?: any) {
     }
 }
 
-// fs.rmdirSync won't delete directories with files in it
-function deleteFolderRecursive(dirPath: string) {
-    if (fs.existsSync(dirPath)) {
-        fs.readdirSync(dirPath).forEach((file) => {
-            const curPath = path.join(dirPath, file);
-            if (fs.statSync(curPath).isDirectory()) { // recurse
-                deleteFolderRecursive(curPath);
-            }
-            else { // delete file
-                fs.unlinkSync(curPath);
-            }
-        });
-        fs.rmdirSync(dirPath);
-    }
-};
-
 function writeFile(path: string, data: any) {
     ensureDirectoriesExist(getDirectoryPath(path));
     fs.writeFileSync(path, data);
diff --git a/tslint.json b/tslint.json
index bcd4dfa2223..de60ad7683a 100644
--- a/tslint.json
+++ b/tslint.json
@@ -7,6 +7,7 @@
             "check-space"
         ],
         "curly":[true, "ignore-same-line"],
+        "debug-assert": true,
         "indent": [true,
             "spaces"
         ],