Disallow tail calls from async functions and generators

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 <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 2487 matching lines @@
           factory()->NewUndefinedLiteral(kNoSourcePosition), pos);
 
       // is_undefined ? this : is_object_conditional
       return_value = factory()->NewConditional(
           is_undefined, ThisExpression(pos), is_object_conditional, pos);
     } else {
       ReturnExprScope maybe_allow_tail_calls(
           function_state_, ReturnExprContext::kInsideValidReturnStatement);
       return_value = ParseExpression(true, CHECK_OK);
 
-      if (allow_tailcalls() && !is_sloppy(language_mode())) {
+      if (allow_tailcalls() && !is_sloppy(language_mode()) && !is_resumable()) {
         // ES6 14.6.1 Static Semantics: IsInTailPosition
         function_state_->AddImplicitTailCallExpression(return_value);
       }
     }
   }
   ExpectSemicolon(CHECK_OK);
 
   if (is_generator()) {
     return_value = BuildIteratorResult(return_value, true);
   } else if (is_async_function()) {
@@ skipping 4204 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8