[es6] Fix completion values of for loops with lexical variables

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 0dc9e6066630898e326880092c60b157e4e8e6a7..235b77f7e355bdab0c935252fa07d2631d3e631f 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -484,7 +484,7 @@ class Block final : public BreakableStatement {
   }
 
   ZoneList<Statement*>* statements() { return &statements_; }
-  bool is_initializer_block() const { return is_initializer_block_; }
+  bool ignore_completion_values() const { return ignore_completion_values_; }

[rossberg, 2015/06/18 05:43:21]

Nit: why the plural?

[conradw, 2015/06/18 10:53:32]

The idea I had in my head was that the block causes each statement inside to
have its completion value ignored. This matches the way the rewriter updates the
value of .return at the level of each individual "base" ExpressionStatement.

The block itself isn't really part of the structure of the program like a normal
block is, since it's neither part of a production nor associated with a scope,
so I thought it would be misleading to talk about the block's "completion
value".

[rossberg, 2015/06/18 10:58:07]

Well, I would argue that's an implementation detail of the rewriter, not a
description of the meaning of the block as such. (Imagine there was no rewriter,
and we compiled these blocks directly.)

 
   static int num_ids() { return parent_num_ids() + 1; }
   BailoutId DeclsId() const { return BailoutId(local_id(0)); }
@@ -499,10 +499,10 @@ class Block final : public BreakableStatement {
 
  protected:
   Block(Zone* zone, ZoneList<const AstRawString*>* labels, int capacity,
-        bool is_initializer_block, int pos)
+        bool ignore_completion_values, int pos)
       : BreakableStatement(zone, labels, TARGET_FOR_NAMED_ONLY, pos),
         statements_(capacity, zone),
-        is_initializer_block_(is_initializer_block),
+        ignore_completion_values_(ignore_completion_values),
         scope_(NULL) {}
   static int parent_num_ids() { return BreakableStatement::num_ids(); }
 
@@ -510,7 +510,7 @@ class Block final : public BreakableStatement {
   int local_id(int n) const { return base_id() + parent_num_ids() + n; }
 
   ZoneList<Statement*> statements_;
-  bool is_initializer_block_;
+  bool ignore_completion_values_;
   Scope* scope_;
 };
 
@@ -3271,12 +3271,10 @@ class AstNodeFactory final BASE_EMBEDDED {
     return new (zone_) ExportDeclaration(zone_, proxy, scope, pos);
   }
 
-  Block* NewBlock(ZoneList<const AstRawString*>* labels,
-                  int capacity,
-                  bool is_initializer_block,
-                  int pos) {
+  Block* NewBlock(ZoneList<const AstRawString*>* labels, int capacity,
+                  bool ignore_completion_values, int pos) {
     return new (zone_)
-        Block(zone_, labels, capacity, is_initializer_block, pos);
+        Block(zone_, labels, capacity, ignore_completion_values, pos);
   }
 
 #define STATEMENT_WITH_LABELS(NodeType)                                     \