[esnext] prototype runtime implementation for async functions

src/parsing/preparser.cc

 // Copyright 2011 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 <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 103 matching lines @@
                           &top_factory);
   scope_->SetLanguageMode(language_mode);
   Scope* function_scope = NewScope(scope_, FUNCTION_SCOPE, kind);
   if (!has_simple_parameters) function_scope->SetHasNonSimpleParameters();
   PreParserFactory function_factory(NULL);
   FunctionState function_state(&function_state_, &scope_, function_scope, kind,
                                &function_factory);
   DCHECK_EQ(Token::LBRACE, scanner()->current_token());
   bool ok = true;
   int start_position = peek_position();
+  function_state.set_parse_phase(FunctionParsePhase::FunctionBody);
   ParseLazyFunctionLiteralBody(&ok, bookmark);
   use_counts_ = nullptr;
   if (bookmark && bookmark->HasBeenReset()) {
     // Do nothing, as we've just aborted scanning this function.
   } else if (stack_overflow()) {
     return kPreParseStackOverflow;
   } else if (!ok) {
     ReportUnexpectedToken(scanner()->current_token());
   } else {
     DCHECK_EQ(Token::RBRACE, scanner()->peek());
@@ skipping 964 matching lines @@
   PreParserFactory factory(NULL);
   FunctionState function_state(&function_state_, &scope_, function_scope, kind,
                                &factory);
   DuplicateFinder duplicate_finder(scanner()->unicode_cache());
   ExpressionClassifier formals_classifier(this, &duplicate_finder);
 
   Expect(Token::LPAREN, CHECK_OK);
   int start_position = scanner()->location().beg_pos;
   function_scope->set_start_position(start_position);
   PreParserFormalParameters formals(function_scope);
+  function_state.set_parse_phase(FunctionParsePhase::FormalParameters);
   ParseFormalParameterList(&formals, &formals_classifier, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
   int formals_end_position = scanner()->location().end_pos;
 
   CheckArityRestrictions(formals.arity, kind, formals.has_rest, start_position,
                          formals_end_position, CHECK_OK);
 
   // See Parser::ParseFunctionLiteral for more information about lazy parsing
   // and lazy compilation.
   bool is_lazily_parsed = (outer_is_script_scope && allow_lazy() &&
                            !function_state_->this_function_is_parenthesized());
 
+  function_state.set_parse_phase(FunctionParsePhase::FunctionBody);
   Expect(Token::LBRACE, CHECK_OK);
   if (is_lazily_parsed) {
     ParseLazyFunctionLiteralBody(CHECK_OK);
   } else {
     ParseStatementList(Token::RBRACE, CHECK_OK);
   }
   Expect(Token::RBRACE, CHECK_OK);
 
   // Parsing the body may change the language mode in our scope.
   language_mode = function_scope->language_mode();
@@ skipping 154 matching lines @@
   //     do '{' StatementList '}'
   Expect(Token::DO, CHECK_OK);
   Expect(Token::LBRACE, CHECK_OK);
   while (peek() != Token::RBRACE) {
     ParseStatementListItem(CHECK_OK);
   }
   Expect(Token::RBRACE, CHECK_OK);
   return PreParserExpression::Default();
 }
 
+void PreParserTraits::ParseAsyncArrowSingleExpressionBody(
+    PreParserStatementList body, bool accept_IN,
+    Type::ExpressionClassifier* classifier, int pos, bool* ok) {
+  Scope* scope = pre_parser_->scope_;
+  scope->ForceContextAllocation();
+
+  PreParserExpression return_value =
+      pre_parser_->ParseAssignmentExpression(accept_IN, classifier, ok);
+  if (!*ok) return;
+
+  body->Add(PreParserStatement::ExpressionStatement(return_value), zone());
+}
+
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8