Implement iterator finalization in array destructuring.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index f838e3a518534aa345151d404d7d4d866b5550c1..ebf85213ef7738dd7ddecbabe47dc0e3b428b56f 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -466,6 +466,9 @@ class ParserTraits {
                             MessageTemplate::Template message,
                             const AstRawString* arg, int pos);
 
+  void FinalizeIteratorUse(Variable* completion, Expression* condition,
+      Variable* iter, Block* iterator_use, Block* result);
+
   Statement* FinalizeForOfStatement(ForOfStatement* loop, int pos);
 
   // Reporting errors.
@@ -674,9 +677,11 @@ class ParserTraits {
 
   void BuildIteratorClose(ZoneList<Statement*>* statements, Variable* iterator,
                           Maybe<Variable*> input, Variable* output);
+
   void BuildIteratorCloseForCompletion(
       ZoneList<Statement*>* statements, Variable* iterator,
-      Variable* body_threw);
+      Variable* completion);
+
   Statement* CheckCallable(Variable* var, Expression* error);
 };
 
@@ -703,6 +708,16 @@ class Parser : public ParserBase<ParserTraits> {
   void Internalize(Isolate* isolate, Handle<Script> script, bool error);
   void HandleSourceURLComments(Isolate* isolate, Handle<Script> script);
 
+  // Runtime encoding of different completion modes.
+  enum CompletionKind {

[adamk, 2016/03/07 20:28:05]

Can you make this an enum class? Otherwise you've effectively added a bunch of
bare names as valid identifiers in all 7000 lines of parser.cc.

[neis, 2016/03/08 13:40:10]

If I make it an enum class, then instead of eg NORMAL etc. I will have to write
static_cast<int>(CompletionKind::NORMAL).  So I prefer keeping it as is.  I made
it private, though (there was no reason for it to be public).

[adamk, 2016/03/08 18:41:13]

Oh, I forgot about that bit. The thing that bothers me is actually the
shortness, not the typing; "NORMAL" is an especially strange identifier to add
if it means something as specific as non-abrupt completion. How about:

kNormalCompletion
kThrowCompletion
kAbruptCompletion

"kThrowCompletion" is a little bit funny, but the others seem reasonable. WDYT?

+    NORMAL = 0,
+    THROW = 1,
+    BREAK = 2,
+    CONTINUE = 4,
+    RETURN = 8,
+    ABRUPT = THROW | BREAK | CONTINUE | RETURN

[adamk, 2016/03/07 20:28:05]

Besides this line, do you actually use this enum as a bit pattern? I didn't see
anyplace on first run through, which suggests to me that it shouldn't be one.

[neis, 2016/03/08 13:40:10]

Alright, changed it back to three values.

+  };
+
  private:
   friend class ParserTraits;
 
@@ -917,6 +932,7 @@ class Parser : public ParserBase<ParserTraits> {
   Statement* ParseForStatement(ZoneList<const AstRawString*>* labels, bool* ok);
   Statement* ParseThrowStatement(bool* ok);
   Expression* MakeCatchContext(Handle<String> id, VariableProxy* value);
+
   class DontCollectExpressionsInTailPositionScope;
   class CollectExpressionsInTailPositionToListScope;
   TryStatement* ParseTryStatement(bool* ok);