Fix scope/context behavior in await transformer.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index f7db62fa973ae6feac63732acdd0e390194e6428..ef268850ef4b1b755bcbb23252e624d1d1fb68e7 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -6255,9 +6255,20 @@ bool Parser::IsSimpleLiteral(const AbstractType& type, Instance* value) {
 }
 
 
-// Returns true if the current token is kIDENT or a pseudo-keyword.
+// Returns true if the current token is
+// * kIDENT,
+// * or a pseudo-keyword,
+// * or is not the literal "await" in an async function.
 bool Parser::IsIdentifier() {
-  return Token::IsIdentifier(CurrentToken());
+  bool is_async = false;
+  if (parsed_function() != NULL) {
+    const Function& func = parsed_function()->function();
+    if (!func.IsNull()) {
+      is_async = func.IsAsyncFunction() || func.is_async_closure();

[hausner, 2014/08/26 20:45:47]

I think this is too expensive. I think it would make sense to cache a boolean
value in the parser object that determines whether "async" is a regular
identifier or a keyword.

The value is known when the parser object is created, I believe.

[Michael Lippautz (Google), 2014/08/26 22:07:44]

Agree. I added the proposed indicator to the parser. It is only set/reset when
actually parsing the function body, i.e., in ParseFunc().

+    }
+  }
+  return Token::IsIdentifier(CurrentToken()) &&
+         (!is_async || (CurrentLiteral()->raw() != Symbols::Await().raw()));
 }
 
 
@@ -8454,11 +8465,12 @@ AstNode* Parser::ParseAwaitableExpr(bool require_compiletime_const,
       // function.
       return expr;
     }
-    SequenceNode* intermediates_block = new(I) SequenceNode(
-        Scanner::kNoSourcePos, current_block_->scope);
-    AwaitTransformer at(intermediates_block, library_, parsed_function());
+    OpenBlock();
+    AwaitTransformer at(current_block_->statements,
+                        library_,
+                        parsed_function());
     AstNode* result = at.Transform(expr);
-    current_block_->statements->Add(intermediates_block);
+    current_block_->statements->Add(CloseBlock());
     parsed_function()->reset_have_seen_await();
     return result;
   }
@@ -10843,7 +10855,7 @@ AstNode* Parser::ParsePrimary() {
     OpenBlock();
     primary = ParseFunctionStatement(true);
     CloseBlock();
-  } else if (IsLiteral("await") &&
+  } else if ((CurrentLiteral()->raw() == Symbols::Await().raw()) &&
              (parsed_function()->function().IsAsyncFunction() ||
               parsed_function()->function().is_async_closure())) {
     // The body of an async function is parsed multiple times. The first time