From 08f9a0148a22c8fd6a65349f684db2b7b0e9bbf9 Mon Sep 17 00:00:00 2001
From: Jason Freeman <jfreeman@microsoft.com>
Date: Thu, 2 Oct 2014 11:24:11 -0700
Subject: [PATCH] Parser changes to parse omitted types correctly

---
 src/compiler/parser.ts | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index b7582b9ed06..3c39a5a0bef 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -1078,7 +1078,7 @@ module ts {
                     return isParameter();
                 case ParsingContext.TypeArguments:
                 case ParsingContext.TupleElementTypes:
-                    return isType();
+                    return token === SyntaxKind.CommaToken || isType();
             }
 
             Debug.fail("Non-exhaustive case in 'isListElement'.");
@@ -2344,13 +2344,24 @@ module ts {
         function parseTypeArguments(): NodeArray<TypeNode> {
             var typeArgumentListStart = scanner.getTokenPos();
             var errorCountBeforeTypeParameterList = file.syntacticErrors.length;
-            var result = parseBracketedList(ParsingContext.TypeArguments, parseType, SyntaxKind.LessThanToken, SyntaxKind.GreaterThanToken);
+            var result = parseBracketedList(ParsingContext.TypeArguments, parseSingleTypeArgument, SyntaxKind.LessThanToken, SyntaxKind.GreaterThanToken);
             if (!result.length && file.syntacticErrors.length === errorCountBeforeTypeParameterList) {
                 grammarErrorAtPos(typeArgumentListStart, scanner.getStartPos() - typeArgumentListStart, Diagnostics.Type_argument_list_cannot_be_empty);
             }
             return result;
         }
 
+        function parseSingleTypeArgument(): TypeNode {
+            if (token === SyntaxKind.CommaToken) {
+                var errorStart = scanner.getTokenPos();
+                var errorLength = scanner.getTextPos() - errorStart;
+                grammarErrorAtPos(errorStart, errorLength, Diagnostics.Type_expected);
+                return createNode(SyntaxKind.OmittedType);
+            }
+
+            return parseType();
+        }
+
         function parsePrimaryExpression(): Expression {
             switch (token) {
                 case SyntaxKind.ThisKeyword: