From 7807ac96f58304e5a6ba979f83005b4e954055e2 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Nov 2016 16:47:43 -0700
Subject: [PATCH] Attach symbols to mapped types

---
 src/compiler/binder.ts  | 3 ++-
 src/compiler/checker.ts | 7 ++-----
 src/compiler/types.ts   | 3 +--
 3 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index e9419ab1cc6..4d923888e86 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -1957,9 +1957,10 @@ namespace ts {
                 case SyntaxKind.JSDocFunctionType:
                     return bindFunctionOrConstructorType(<SignatureDeclaration>node);
                 case SyntaxKind.TypeLiteral:
+                case SyntaxKind.MappedType:
                 case SyntaxKind.JSDocTypeLiteral:
                 case SyntaxKind.JSDocRecordType:
-                    return bindAnonymousDeclaration(<TypeLiteralNode>node, SymbolFlags.TypeLiteral, "__type");
+                    return bindAnonymousDeclaration(<Declaration>node, SymbolFlags.TypeLiteral, "__type");
                 case SyntaxKind.ObjectLiteralExpression:
                     return bindObjectLiteralExpression(<ObjectLiteralExpression>node);
                 case SyntaxKind.FunctionExpression:
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 7e87980cf15..afd2b50c871 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -5884,10 +5884,8 @@ namespace ts {
 
         function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode) {
             if (indexType.flags & TypeFlags.TypeParameter) {
-                if (!isTypeAssignableTo(getConstraintOfTypeParameter(<TypeParameter>indexType) || emptyObjectType, getIndexType(objectType))) {
-                    if (accessNode) {
-                        error(accessNode, Diagnostics.Type_0_is_not_constrained_to_keyof_1, typeToString(indexType), typeToString(objectType));
-                    }
+                if (accessNode && !isTypeAssignableTo(getConstraintOfTypeParameter(<TypeParameter>indexType) || emptyObjectType, getIndexType(objectType))) {
+                    error(accessNode, Diagnostics.Type_0_is_not_constrained_to_keyof_1, typeToString(indexType), typeToString(objectType));
                     return unknownType;
                 }
                 return getIndexedAccessTypeForTypeParameter(objectType, <TypeParameter>indexType);
@@ -5919,7 +5917,6 @@ namespace ts {
             const links = getNodeLinks(node);
             if (!links.resolvedType) {
                 const type = <MappedType>createObjectType(ObjectFlags.Mapped);
-                type.declaration = node;
                 type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfNode(node.typeParameter));
                 type.templateType = node.type ? getTypeFromTypeNode(node.type) : anyType;
                 type.aliasSymbol = aliasSymbol;
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 36d0d3fd7b9..fcd5b68950b 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2497,7 +2497,7 @@ namespace ts {
         RegularEnum             = 0x00000100,  // Enum
         ValueModule             = 0x00000200,  // Instantiated module
         NamespaceModule         = 0x00000400,  // Uninstantiated module
-        TypeLiteral             = 0x00000800,  // Type Literal
+        TypeLiteral             = 0x00000800,  // Type Literal or mapped type
         ObjectLiteral           = 0x00001000,  // Object Literal
         Method                  = 0x00002000,  // Method
         Constructor             = 0x00004000,  // Constructor
@@ -2848,7 +2848,6 @@ namespace ts {
 
     /* @internal */
     export interface MappedType extends ObjectType {
-        declaration: MappedTypeNode;
         typeParameter: TypeParameter;
         templateType: Type;
         target?: MappedType;  // Instantiation target