[es8] Report proper syntax error for tail call expressions in for-in and for-of bodies.

src/parsing/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 2621 matching lines @@
 
       // is_undefined ? this : is_object_conditional
       return_value = factory()->NewConditional(
           is_undefined, ThisExpression(scope_, factory(), pos),
           is_object_conditional, pos);
     }
 
     // TODO(ishell): update chapter number.
     // ES8 XX.YY.ZZ
     if (tail_call_position >= 0) {
-      if (!function_state_->collect_expressions_in_tail_position()) {
+      ReturnExprContext return_expr_context =
+          function_state_->return_expr_context();
+      if (return_expr_context != ReturnExprContext::kNormal) {
         Scanner::Location loc(tail_call_position, tail_call_position + 1);
-        ReportMessageAt(loc, MessageTemplate::kTailCallInTryBlock);
+        MessageTemplate::Template msg =
+            return_expr_context == ReturnExprContext::kInsideTryBlock
+                ? MessageTemplate::kTailCallInTryBlock
+                : MessageTemplate::kTailCallInForInOf;
+        ReportMessageAt(loc, msg);
         *ok = false;
         return NULL;
       }
       function_state_->AddExpressionInTailPosition(return_value,
                                                    tail_call_position);
 
     } else if (allow_tailcalls() && !is_sloppy(language_mode())) {
       // ES6 14.6.1 Static Semantics: IsInTailPosition
       function_state_->AddExpressionInTailPosition(return_value, pos);
     }
@@ skipping 186 matching lines @@
   //   'catch' '(' Identifier ')' Block
   //
   // Finally ::
   //   'finally' Block
 
   Expect(Token::TRY, CHECK_OK);
   int pos = position();
 
   Block* try_block;
   {
-    DontCollectExpressionsInTailPositionScope no_tail_calls(function_state_);
+    ReturnExprScope no_tail_calls(function_state_,
+                                  ReturnExprContext::kInsideTryBlock);
     try_block = ParseBlock(NULL, CHECK_OK);
   }
 
   Token::Value tok = peek();
   if (tok != Token::CATCH && tok != Token::FINALLY) {
     ReportMessage(MessageTemplate::kNoCatchOrFinally);
     *ok = false;
     return NULL;
   }
 
@@ skipping 686 matching lines @@
 
         Expect(Token::RPAREN, CHECK_OK);
 
         Scope* body_scope = NewScope(scope_, BLOCK_SCOPE);
         body_scope->set_start_position(scanner()->location().beg_pos);
 
         Block* body_block =
             factory()->NewBlock(NULL, 3, false, RelocInfo::kNoPosition);
 
         {
-          DontCollectExpressionsInTailPositionScope no_tail_calls(
-              function_state_);
+          ReturnExprScope no_tail_calls(function_state_,
+                                        ReturnExprContext::kInsideForInOfBody);
           BlockState block_state(&scope_, body_scope);
 
           Statement* body = ParseScopedStatement(NULL, true, CHECK_OK);
 
           auto each_initialization_block =
               factory()->NewBlock(nullptr, 1, true, RelocInfo::kNoPosition);
           {
             auto descriptor = parsing_result.descriptor;
             descriptor.declaration_pos = RelocInfo::kNoPosition;
             descriptor.initialization_pos = RelocInfo::kNoPosition;
@@ skipping 3223 matching lines @@
                         try_block, target);
     final_loop = target;
   }
 
   return final_loop;
 }
 
 
 }  // namespace internal
 }  // namespace v8