Don't reflect ES2015 Function name inference in Function.prototype.toString

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 710 matching lines @@
 
 Expression* ParserTraits::ParseV8Intrinsic(bool* ok) {
   return parser_->ParseV8Intrinsic(ok);
 }
 
 
 FunctionLiteral* ParserTraits::ParseFunctionLiteral(
     const AstRawString* name, Scanner::Location function_name_location,
     FunctionNameValidity function_name_validity, FunctionKind kind,
     int function_token_position, FunctionLiteral::FunctionType type,
-    FunctionLiteral::ArityRestriction arity_restriction,
     LanguageMode language_mode, bool* ok) {
   return parser_->ParseFunctionLiteral(
       name, function_name_location, function_name_validity, kind,
-      function_token_position, type, arity_restriction, language_mode, ok);
+      function_token_position, type, language_mode, ok);
 }
 
 
 ClassLiteral* ParserTraits::ParseClassLiteral(
     const AstRawString* name, Scanner::Location class_name_location,
     bool name_is_strict_reserved, int pos, bool* ok) {
   return parser_->ParseClassLiteral(name, class_name_location,
                                     name_is_strict_reserved, pos, ok);
 }
 
@@ skipping 191 matching lines @@
           !body->at(0)->IsExpressionStatement() ||
           !body->at(0)->AsExpressionStatement()->
               expression()->IsFunctionLiteral()) {
         ReportMessage(MessageTemplate::kSingleFunctionLiteral);
         ok = false;
       }
     }
 
     if (ok) {
       ParserTraits::RewriteDestructuringAssignments();
-      result = factory()->NewFunctionLiteral(
-          ast_value_factory()->empty_string(), scope_, body,
-          function_state.materialized_literal_count(),
-          function_state.expected_property_count(), 0,
-          FunctionLiteral::kNoDuplicateParameters,
-          FunctionLiteral::kGlobalOrEval, FunctionLiteral::kShouldLazyCompile,
-          FunctionKind::kNormalFunction, 0);
+      result = factory()->NewGlobalOrEvalFunctionLiteral(
+          scope_, body, function_state.materialized_literal_count(),
+          function_state.expected_property_count());
     }
   }
 
   // Make sure the target stack is empty.
   DCHECK(target_stack_ == NULL);
 
   return result;
 }
 
 
@@ skipping 66 matching lines @@
       scope = Scope::DeserializeScopeChain(isolate, zone(),
                                            info->closure()->context(), scope);
     }
     original_scope_ = scope;
     AstNodeFactory function_factory(ast_value_factory());
     FunctionState function_state(&function_state_, &scope_, scope,
                                  shared_info->kind(), &function_factory);
     DCHECK(is_sloppy(scope->language_mode()) ||
            is_strict(info->language_mode()));
     DCHECK(info->language_mode() == shared_info->language_mode());
+    // TODO(adamk): kAnonymousExpression isn't necessarily correct, but it's
+    // a safe default.

[Dan Ehrenberg, 2016/02/19 00:10:41]

Could this cause the getter/setter/method-ness to be lost in practice, or are
those always going to be parsed together with the class/object literal?

[adamk, 2016/02/19 01:09:15]

So this is indeed the only really ugly bit of the change. kDeclaration,
kNamedExpression, and kAnonymousExpression are all bits that matter both at
initial parse (or preparse time) and at runtime.

But the other FunctionLiteral::FunctionType values only matter at initial parse
time. kMethod doesn't have any special behavior at all (besides not being one of
the others) while kGetter and kSetter produce an error (or not) on initial parse
(which means we'd never get into the position of lazily parsing again).

I could reconstruct the Method-ness from FunctionKind, but not the Getter vs
Setter.

Any suggestions? This indeed looks pretty brittle; if someone started to depend
on FunctionType::kGetter in another way, we'd end up with an inconsistency
between first parse and lazy parsing (or first compilation and subsequent
optimization).

[adamk, 2016/02/19 02:02:19]

Since I had the bit free anyway, split FunctionKind::kAccessorFunction into
kGetterFunction and kSetterFunction. Now the Getter or Setter-ness is stored in
the SFI. So we still avoid needing a separate ArityRestriction argument at the
cost of one bit in SFI.

Seems like a reasonable tradeoff for readability, to me.

     FunctionLiteral::FunctionType function_type =
-        shared_info->is_expression()
-            ? (shared_info->is_anonymous()
-                   ? FunctionLiteral::kAnonymousExpression
-                   : FunctionLiteral::kNamedExpression)
-            : FunctionLiteral::kDeclaration;
+        shared_info->is_declaration()
+            ? FunctionLiteral::kDeclaration
+            : (shared_info->is_named_expression()
+                   ? FunctionLiteral::kNamedExpression
+                   : FunctionLiteral::kAnonymousExpression);
     bool ok = true;
 
     if (shared_info->is_arrow()) {
       // TODO(adamk): We should construct this scope from the ScopeInfo.
       Scope* scope =
           NewScope(scope_, FUNCTION_SCOPE, FunctionKind::kArrowFunction);
 
       // These two bits only need to be explicitly set because we're
       // not passing the ScopeInfo to the Scope constructor.
       // TODO(adamk): Remove these calls once the above NewScope call
@@ skipping 48 matching lines @@
             ok = false;
           }
         }
       }
     } else if (shared_info->is_default_constructor()) {
       result = DefaultConstructor(
           raw_name, IsSubclassConstructor(shared_info->kind()), scope,
           shared_info->start_position(), shared_info->end_position(),
           shared_info->language_mode());
     } else {
-      result = ParseFunctionLiteral(
-          raw_name, Scanner::Location::invalid(), kSkipFunctionNameCheck,
-          shared_info->kind(), RelocInfo::kNoPosition, function_type,
-          FunctionLiteral::kNormalArity, shared_info->language_mode(), &ok);
+      result = ParseFunctionLiteral(raw_name, Scanner::Location::invalid(),
+                                    kSkipFunctionNameCheck, shared_info->kind(),
+                                    RelocInfo::kNoPosition, function_type,
+                                    shared_info->language_mode(), &ok);
     }
     // Make sure the results agree.
     DCHECK(ok == (result != NULL));
   }
 
   // Make sure the target stack is empty.
   DCHECK(target_stack_ == NULL);
 
   if (result != NULL) {
     Handle<String> inferred_name(shared_info->inferred_name());
@@ skipping 443 matching lines @@
         // FunctionDeclaration[+Default] ::
         //   'function' '(' FormalParameters ')' '{' FunctionBody '}'
         //
         // GeneratorDeclaration[+Default] ::
         //   'function' '*' '(' FormalParameters ')' '{' FunctionBody '}'
         default_export = ParseFunctionLiteral(
             default_string, Scanner::Location::invalid(),
             kSkipFunctionNameCheck,
             is_generator ? FunctionKind::kGeneratorFunction
                          : FunctionKind::kNormalFunction,
-            pos, FunctionLiteral::kDeclaration, FunctionLiteral::kNormalArity,
-            language_mode(), CHECK_OK);
+            pos, FunctionLiteral::kDeclaration, language_mode(), CHECK_OK);
         result = factory()->NewEmptyStatement(RelocInfo::kNoPosition);
       } else {
         result = ParseFunctionDeclaration(pos, is_generator, &names, CHECK_OK);
       }
       break;
     }
 
     case Token::CLASS:
       Consume(Token::CLASS);
       if (peek() == Token::EXTENDS || peek() == Token::LBRACE) {
@@ skipping 550 matching lines @@
       &is_strict_reserved, CHECK_OK);
 
   FuncNameInferrer::State fni_state(fni_);
   if (fni_ != NULL) fni_->PushEnclosingName(name);
   FunctionLiteral* fun = ParseFunctionLiteral(
       name, scanner()->location(),
       is_strict_reserved ? kFunctionNameIsStrictReserved
                          : kFunctionNameValidityUnknown,
       is_generator ? FunctionKind::kGeneratorFunction
                    : FunctionKind::kNormalFunction,
-      pos, FunctionLiteral::kDeclaration, FunctionLiteral::kNormalArity,
-      language_mode(), CHECK_OK);
+      pos, FunctionLiteral::kDeclaration, language_mode(), CHECK_OK);
 
   // Even if we're not at the top-level of the global or a function
   // scope, we treat it as such and introduce the function with its
   // initial value upon entering the corresponding scope.
   // In ES6, a function behaves as a lexical binding, except in
   // a script scope, or the initial scope of eval or another function.
   VariableMode mode =
       is_strong(language_mode())
           ? CONST
           : (is_strict(language_mode()) || allow_harmony_sloppy_function()) &&
@@ skipping 1974 matching lines @@
     DCHECK(reindexer.count() <=
            parser_->function_state_->materialized_literal_count());
   }
 }
 
 
 FunctionLiteral* Parser::ParseFunctionLiteral(
     const AstRawString* function_name, Scanner::Location function_name_location,
     FunctionNameValidity function_name_validity, FunctionKind kind,
     int function_token_pos, FunctionLiteral::FunctionType function_type,
-    FunctionLiteral::ArityRestriction arity_restriction,
     LanguageMode language_mode, bool* ok) {
   // Function ::
   //   '(' FormalParameterList? ')' '{' FunctionBody '}'
   //
   // Getter ::
   //   '(' ')' '{' FunctionBody '}'
   //
   // Setter ::
   //   '(' PropertySetParameterList ')' '{' FunctionBody '}'
 
@@ skipping 82 matching lines @@
 
     Expect(Token::LPAREN, CHECK_OK);
     int start_position = scanner()->location().beg_pos;
     scope_->set_start_position(start_position);
     ParserFormalParameters formals(scope);
     ParseFormalParameterList(&formals, &formals_classifier, CHECK_OK);
     arity = formals.Arity();
     Expect(Token::RPAREN, CHECK_OK);
     int formals_end_position = scanner()->location().end_pos;
 
-    CheckArityRestrictions(arity, arity_restriction,
-                           formals.has_rest, start_position,
-                           formals_end_position, CHECK_OK);
+    CheckArityRestrictions(arity, function_type, formals.has_rest,
+                           start_position, formals_end_position, CHECK_OK);
     Expect(Token::LBRACE, CHECK_OK);
 
     // Don't include the rest parameter into the function's formal parameter
     // count (esp. the SharedFunctionInfo::internal_formal_parameter_count,
     // which says whether we need to create an arguments adaptor frame).
     if (formals.has_rest) arity--;
 
     // Determine if the function can be parsed lazily. Lazy parsing is different
     // from lazy compilation; we need to parse more eagerly than we compile.
 
@@ skipping 1486 matching lines @@
 void ParserTraits::QueueDestructuringAssignmentForRewriting(Expression* expr) {
   DCHECK(expr->IsRewritableAssignmentExpression());
   parser_->function_state_->AddDestructuringAssignment(
       Parser::DestructuringAssignment(expr, parser_->scope_));
 }
 
 
 void ParserTraits::SetFunctionNameFromPropertyName(
     ObjectLiteralProperty* property, const AstRawString* name) {
   Expression* value = property->value();
-  if (!value->IsAnonymousFunctionDefinition()) return;
 
   // Computed name setting must happen at runtime.
   if (property->is_computed_name()) return;
 
+  // Getter and setter names are handled here because their names
+  // change in ES2015, even though they are not anonymous.
+  auto function = value->AsFunctionLiteral();
+  if (function != nullptr) {
+    bool is_getter = property->kind() == ObjectLiteralProperty::GETTER;
+    bool is_setter = property->kind() == ObjectLiteralProperty::SETTER;
+    if (is_getter || is_setter) {
+      DCHECK_NOT_NULL(name);
+      const AstRawString* prefix =
+          is_getter ? parser_->ast_value_factory()->get_space_string()
+                    : parser_->ast_value_factory()->set_space_string();
+      function->set_raw_name(
+          parser_->ast_value_factory()->NewConsString(prefix, name));
+      return;
+    }
+  }
+
+  if (!value->IsAnonymousFunctionDefinition()) return;
   DCHECK_NOT_NULL(name);
 
   // Ignore "__proto__" as a name when it's being used to set the [[Prototype]]
   // of an object literal.
   if (property->kind() == ObjectLiteralProperty::PROTOTYPE) return;
 
-  auto function = value->AsFunctionLiteral();
   if (function != nullptr) {
-    if (property->kind() == ObjectLiteralProperty::GETTER) {
-      function->set_raw_name(parser_->ast_value_factory()->NewConsString(
-          parser_->ast_value_factory()->get_space_string(), name));
-    } else if (property->kind() == ObjectLiteralProperty::SETTER) {
-      function->set_raw_name(parser_->ast_value_factory()->NewConsString(
-          parser_->ast_value_factory()->set_space_string(), name));
-    } else {
-      function->set_raw_name(name);
-      DCHECK_EQ(ObjectLiteralProperty::COMPUTED, property->kind());
-    }
+    function->set_raw_name(name);
+    DCHECK_EQ(ObjectLiteralProperty::COMPUTED, property->kind());
   } else {
     DCHECK(value->IsClassLiteral());
     DCHECK_EQ(ObjectLiteralProperty::COMPUTED, property->kind());
     value->AsClassLiteral()->constructor()->set_raw_name(name);
   }
 }
 
 
 void ParserTraits::SetFunctionNameFromIdentifierRef(Expression* value,
                                                     Expression* identifier) {
@@ skipping 933 matching lines @@
   new_body->statements()->Add(loop->body(), zone);
   new_body->statements()->Add(set_completion_normal, zone);
 
   loop->set_body(new_body);
   return final_loop;
 }
 
 
 }  // namespace internal
 }  // namespace v8