[parser] improve inferred function names for async arrow functions

src/parsing/parser-base.h

 // 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.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
 #include "src/base/hashmap.h"
@@ skipping 2304 matching lines @@
   ExpressionT expression;
   if (IsTrivialExpression()) {
     expression = this->ParsePrimaryExpression(&arrow_formals_classifier,
                                               &is_async, CHECK_OK);
   } else {
     expression = this->ParseConditionalExpression(
         accept_IN, &arrow_formals_classifier, CHECK_OK);
   }
 
   if (is_async && peek_any_identifier() && PeekAhead() == Token::ARROW) {
-    // async Identifier => AsyncConciseBody
-    IdentifierT name =
-        ParseAndClassifyIdentifier(&arrow_formals_classifier, CHECK_OK);
-    expression = this->ExpressionFromIdentifier(name, position(),
-                                                scanner()->location().end_pos);
+    if (this->IsIdentifier(expression)) {
+      // async Identifier => AsyncConciseBody
+      IdentifierT name =
+          ParseAndClassifyIdentifier(&arrow_formals_classifier, CHECK_OK);
+      expression = this->ExpressionFromIdentifier(
+          name, position(), scanner()->location().end_pos, InferName::No);
+      if (fni_) {
+        // Remove `async` keyword from inferred name stack.
+        fni_->RemoveAsyncKeywordAtIndex(fni_->LastNameIndex());
+      }
+    }
   }
 
   if (peek() == Token::ARROW) {
     Scanner::Location arrow_loc = scanner()->peek_location();
     ValidateArrowFormalParameters(&arrow_formals_classifier, expression,
                                   parenthesized_formals, is_async, CHECK_OK);
     // This reads strangely, but is correct: it checks whether any
     // sub-expression of the parameter list failed to be a valid formal
     // parameter initializer. Since YieldExpressions are banned anywhere
     // in an arrow parameter list, this is correct.
@@ skipping 535 matching lines @@
           pos = peek_position();
           // Also the trailing parenthesis are a hint that the function will
           // be called immediately. If we happen to have parsed a preceding
           // function literal eagerly, we can also compile it eagerly.
           if (result->IsFunctionLiteral() && mode() == PARSE_EAGERLY) {
             result->AsFunctionLiteral()->set_should_eager_compile();
           }
         }
         Scanner::Location spread_pos;
         typename Traits::Type::ExpressionList args;
-        if (V8_UNLIKELY(is_async)) {
+        if (V8_UNLIKELY(is_async && this->IsIdentifier(result))) {
+          int async_index = fni_ ? fni_->LastNameIndex() : -1;
           ExpressionClassifier async_classifier(this);
           args = ParseArguments(&spread_pos, true, &async_classifier, CHECK_OK);
           if (peek() == Token::ARROW) {
+            if (fni_) {
+              fni_->RemoveAsyncKeywordAtIndex(async_index);
+            }
             ValidateBindingPattern(&async_classifier, CHECK_OK);
             if (!async_classifier.is_valid_async_arrow_formal_parameters()) {
               ReportClassifierError(
                   async_classifier.async_arrow_formal_parameters_error());
               *ok = false;
               return this->EmptyExpression();
             }
             if (args->length()) {
               // async ( Arguments ) => ...
               return Traits::ExpressionListToExpression(args);
@@ skipping 823 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H