[parser] Fix scopes in rewriting of for-of and destructuring assignments.

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 79d06da50750fca179203bb8abd768b07043d76d..b6d06e3c6656154dbb889114831b54d157cf72b5 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -4309,8 +4309,16 @@ void Parser::RewriteDestructuringAssignments() {
         pair.assignment->AsRewritableExpression();
     DCHECK_NOT_NULL(to_rewrite);
     if (!to_rewrite->is_rewritten()) {
-      PatternRewriter::RewriteDestructuringAssignment(this, to_rewrite,
-                                                      pair.scope);
+      // Since this function is called at the end of parsing the program,
+      // pair.scope may already have been removed by FinalizeBlockScope in the
+      // meantime.  In that case, use the first outer non-removed scope.
+      Scope* scope = pair.scope;
+      while (scope != nullptr && scope->HasBeenRemoved()) {

[Toon Verwaest, 2016/11/23 12:20:45]

Move to helper function as mentioned before.

+        scope = scope->outer_scope();
+      }
+      DCHECK_NOT_NULL(scope);
+
+      PatternRewriter::RewriteDestructuringAssignment(this, to_rewrite, scope);
     }
   }
 }
@@ -4745,7 +4753,7 @@ Expression* Parser::RewriteYieldStar(Expression* generator,
 
     Block* then = factory()->NewBlock(nullptr, 4 + 1, false, nopos);
     BuildIteratorCloseForCompletion(
-        then->statements(), var_iterator,
+        scope(), then->statements(), var_iterator,
         factory()->NewSmiLiteral(Parser::kNormalCompletion, nopos));
     then->statements()->Add(throw_call, zone());
     check_throw = factory()->NewIfStatement(
@@ -5113,9 +5121,9 @@ void Parser::BuildIteratorClose(ZoneList<Statement*>* statements,
   statements->Add(validate_output, zone());
 }
 
-void Parser::FinalizeIteratorUse(Variable* completion, Expression* condition,
-                                 Variable* iter, Block* iterator_use,
-                                 Block* target) {
+void Parser::FinalizeIteratorUse(Scope* use_scope, Variable* completion,
+                                 Expression* condition, Variable* iter,
+                                 Block* iterator_use, Block* target) {
   //
   // This function adds two statements to [target], corresponding to the
   // following code:
@@ -5171,7 +5179,8 @@ void Parser::FinalizeIteratorUse(Variable* completion, Expression* condition,
   {
     Block* block = factory()->NewBlock(nullptr, 2, true, nopos);
     Expression* proxy = factory()->NewVariableProxy(completion);
-    BuildIteratorCloseForCompletion(block->statements(), iter, proxy);
+    BuildIteratorCloseForCompletion(use_scope, block->statements(), iter,
+                                    proxy);
     DCHECK(block->statements()->length() == 2);
 
     maybe_close = factory()->NewBlock(nullptr, 1, true, nopos);
@@ -5188,7 +5197,7 @@ void Parser::FinalizeIteratorUse(Variable* completion, Expression* condition,
   // }
   Statement* try_catch;
   {
-    Scope* catch_scope = NewScopeWithParent(scope(), CATCH_SCOPE);
+    Scope* catch_scope = NewScopeWithParent(use_scope, CATCH_SCOPE);
     Variable* catch_variable =
         catch_scope->DeclareLocal(ast_value_factory()->dot_catch_string(), VAR,
                                   kCreatedInitialized, NORMAL_VARIABLE);
@@ -5228,7 +5237,8 @@ void Parser::FinalizeIteratorUse(Variable* completion, Expression* condition,
   target->statements()->Add(try_finally, zone());
 }
 
-void Parser::BuildIteratorCloseForCompletion(ZoneList<Statement*>* statements,
+void Parser::BuildIteratorCloseForCompletion(Scope* scope,
+                                             ZoneList<Statement*>* statements,
                                              Variable* iterator,
                                              Expression* completion) {
   //
@@ -5294,7 +5304,7 @@ void Parser::BuildIteratorCloseForCompletion(ZoneList<Statement*>* statements,
 
     Block* catch_block = factory()->NewBlock(nullptr, 0, false, nopos);
 
-    Scope* catch_scope = NewScope(CATCH_SCOPE);
+    Scope* catch_scope = NewScopeWithParent(scope, CATCH_SCOPE);
     Variable* catch_variable =
         catch_scope->DeclareLocal(ast_value_factory()->dot_catch_string(), VAR,
                                   kCreatedInitialized, NORMAL_VARIABLE);
@@ -5431,8 +5441,13 @@ Statement* Parser::FinalizeForOfStatement(ForOfStatement* loop,
     Block* try_block = factory()->NewBlock(nullptr, 1, false, nopos);
     try_block->statements()->Add(loop, zone());
 
-    FinalizeIteratorUse(var_completion, closing_condition, loop->iterator(),
-                        try_block, final_loop);
+    // The scope in which the parser creates this loop.
+    Scope* loop_scope = scope()->outer_scope();
+    DCHECK_EQ(loop_scope->scope_type(), BLOCK_SCOPE);
+    DCHECK_EQ(scope()->scope_type(), BLOCK_SCOPE);
+
+    FinalizeIteratorUse(loop_scope, var_completion, closing_condition,
+                        loop->iterator(), try_block, final_loop);
   }
 
   return final_loop;