From 26713c8721aefe852245b191cf1db129eb881f77 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Tue, 19 Jul 2016 07:18:16 -0700
Subject: [PATCH] Expand top level of declared type in type alias declaration

---
 src/compiler/checker.ts  | 13 +++++++------
 src/compiler/types.ts    |  1 +
 src/services/services.ts |  2 +-
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 33c6e750f16..60673b4a588 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2110,6 +2110,7 @@ namespace ts {
                 return writeType(type, globalFlags);
 
                 function writeType(type: Type, flags: TypeFormatFlags) {
+                    const nextFlags = flags & ~TypeFormatFlags.InTypeAlias;
                     // Write undefined/null type as any
                     if (type.flags & TypeFlags.Intrinsic) {
                         // Special handling for unknown / resolving types, they should show up as any and not unknown or __resolving
@@ -2124,24 +2125,24 @@ namespace ts {
                         writer.writeKeyword("this");
                     }
                     else if (type.flags & TypeFlags.Reference) {
-                        writeTypeReference(<TypeReference>type, flags);
+                        writeTypeReference(<TypeReference>type, nextFlags);
                     }
                     else if (type.flags & (TypeFlags.Class | TypeFlags.Interface | TypeFlags.Enum | TypeFlags.TypeParameter)) {
                         // The specified symbol flags need to be reinterpreted as type flags
-                        buildSymbolDisplay(type.symbol, writer, enclosingDeclaration, SymbolFlags.Type, SymbolFormatFlags.None, flags);
+                        buildSymbolDisplay(type.symbol, writer, enclosingDeclaration, SymbolFlags.Type, SymbolFormatFlags.None, nextFlags);
                     }
                     else if (type.flags & TypeFlags.Tuple) {
                         writeTupleType(<TupleType>type);
                     }
-                    else if (type.flags & (TypeFlags.Anonymous | TypeFlags.UnionOrIntersection) && type.aliasSymbol) {
+                    else if (!(flags & TypeFormatFlags.InTypeAlias) && type.flags & (TypeFlags.Anonymous | TypeFlags.UnionOrIntersection) && type.aliasSymbol) {
                         const typeArguments = type.aliasTypeArguments;
-                        writeSymbolTypeReference(type.aliasSymbol, typeArguments, 0, typeArguments ? typeArguments.length : 0, flags);
+                        writeSymbolTypeReference(type.aliasSymbol, typeArguments, 0, typeArguments ? typeArguments.length : 0, nextFlags);
                     }
                     else if (type.flags & TypeFlags.UnionOrIntersection) {
-                        writeUnionOrIntersectionType(<UnionOrIntersectionType>type, flags);
+                        writeUnionOrIntersectionType(<UnionOrIntersectionType>type, nextFlags);
                     }
                     else if (type.flags & TypeFlags.Anonymous) {
-                        writeAnonymousType(<ObjectType>type, flags);
+                        writeAnonymousType(<ObjectType>type, nextFlags);
                     }
                     else if (type.flags & TypeFlags.StringLiteral) {
                         writer.writeStringLiteral(`"${escapeString((<LiteralType>type).text)}"`);
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index e9ffb8bff72..5174bc5732b 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -1913,6 +1913,7 @@ namespace ts {
         InElementType                   = 0x00000040,  // Writing an array or union element type
         UseFullyQualifiedType           = 0x00000080,  // Write out the fully qualified type name (eg. Module.Type, instead of Type)
         InFirstTypeArgument             = 0x00000100,  // Writing first type argument of the instantiated type
+        InTypeAlias                     = 0x00000200,  // Writing type in type alias declaration
     }
 
     export const enum SymbolFormatFlags {
diff --git a/src/services/services.ts b/src/services/services.ts
index 6586930c343..5bcd5ee28c4 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -4606,7 +4606,7 @@ namespace ts {
                 displayParts.push(spacePart());
                 displayParts.push(operatorPart(SyntaxKind.EqualsToken));
                 displayParts.push(spacePart());
-                addRange(displayParts, typeToDisplayParts(typeChecker, typeChecker.getDeclaredTypeOfSymbol(symbol), enclosingDeclaration));
+                addRange(displayParts, typeToDisplayParts(typeChecker, typeChecker.getDeclaredTypeOfSymbol(symbol), enclosingDeclaration, TypeFormatFlags.InTypeAlias));
             }
             if (symbolFlags & SymbolFlags.Enum) {
                 addNewLineIfDisplayPartsExist();