VM: Allow trailing comma in assert statements.

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 9679 matching lines @@
 
 AstNode* Parser::ParseAssertStatement(bool is_const) {
   TRACE_PARSER("ParseAssertStatement");
   ConsumeToken();  // Consume assert keyword.
   ExpectToken(Token::kLPAREN);
   const TokenPosition condition_pos = TokenPos();
   if (!I->asserts()) {
     SkipExpr();
     if (CurrentToken() == Token::kCOMMA) {
       ConsumeToken();
-      SkipExpr();
+      if (CurrentToken() != Token::kRPAREN) {
+        SkipExpr();
+        if (CurrentToken() == Token::kCOMMA) {
+          // Allow trailing comma.
+          ConsumeToken();
+        }
+      }
     }
     ExpectToken(Token::kRPAREN);
     return NULL;
   }
 
   BoolScope saved_seen_await(&parsed_function()->have_seen_await_expr_, false);
   AstNode* condition = ParseExpr(kAllowConst, kConsumeCascades);
   if (is_const && !condition->IsPotentiallyConst()) {
     ReportError(condition_pos,
                 "initializer assert expression must be compile time constant.");
   }
   const TokenPosition condition_end = TokenPos();
   AstNode* message = NULL;
   TokenPosition message_pos = TokenPosition::kNoSource;
   if (CurrentToken() == Token::kCOMMA) {
     ConsumeToken();
-    message_pos = TokenPos();
-    message = ParseExpr(kAllowConst, kConsumeCascades);
-    if (is_const && !message->IsPotentiallyConst()) {
-      ReportError(
-          message_pos,
-          "initializer assert expression must be compile time constant.");
+    if (CurrentToken() != Token::kRPAREN) {
+      message_pos = TokenPos();
+      message = ParseExpr(kAllowConst, kConsumeCascades);
+      if (is_const && !message->IsPotentiallyConst()) {
+        ReportError(
+            message_pos,
+            "initializer assert expression must be compile time constant.");
+      }
+      if (CurrentToken() == Token::kCOMMA) {
+        // Allow trailing comma.
+        ConsumeToken();
+      }
     }
   }
   ExpectToken(Token::kRPAREN);
 
   if (!is_const) {
     // Check for assertion condition being a function if not const.
     ArgumentListNode* arguments = new (Z) ArgumentListNode(condition_pos);
     arguments->Add(condition);
     condition = MakeStaticCall(
         Symbols::AssertionError(),
@@ skipping 5580 matching lines @@
                                                 TokenPosition* start,
                                                 TokenPosition* end) {
   UNREACHABLE();
   return false;
 }
 
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME