Disallow generator declarations in certain locations

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 160 matching lines @@
   //
   // HoistableDeclaration[Yield, Default] :
   //   FunctionDeclaration[?Yield, ?Default]
   //   GeneratorDeclaration[?Yield, ?Default]
   //
   // LexicalDeclaration[In, Yield] :
   //   LetOrConst BindingList[?In, ?Yield] ;
 
   switch (peek()) {
     case Token::FUNCTION:
-      return ParseFunctionDeclaration(ok);
+      return ParseHoistableDeclaration(ok);
     case Token::CLASS:
       return ParseClassDeclaration(ok);
     case Token::CONST:
       return ParseVariableStatement(kStatementListItem, ok);
     case Token::LET:
       if (IsNextLetKeyword()) {
         return ParseVariableStatement(kStatementListItem, ok);
       }
       break;
     default:
@@ skipping 79 matching lines @@
     return Statement::Default();
   }
   return ParseSubStatement(allow_function, ok);
 }
 
 PreParser::Statement PreParser::ParseScopedStatement(bool legacy, bool* ok) {
   if (is_strict(language_mode()) || peek() != Token::FUNCTION ||
       (legacy && allow_harmony_restrictive_declarations())) {
     return ParseSubStatement(kDisallowLabelledFunctionStatement, ok);
   } else {
-    return ParseFunctionDeclaration(CHECK_OK);
+    return ParseFunctionDeclaration(ok);
   }
 }
 
 PreParser::Statement PreParser::ParseSubStatement(
     AllowLabelledFunctionStatement allow_function, bool* ok) {
   // Statement ::
   //   Block
   //   VariableStatement
   //   EmptyStatement
   //   ExpressionStatement
@@ skipping 76 matching lines @@
 
     case Token::VAR:
       return ParseVariableStatement(kStatement, ok);
 
     default:
       return ParseExpressionOrLabelledStatement(allow_function, ok);
   }
 }
 
 
-PreParser::Statement PreParser::ParseFunctionDeclaration(bool* ok) {
-  // FunctionDeclaration ::
-  //   'function' Identifier '(' FormalParameterListopt ')' '{' FunctionBody '}'
-  // GeneratorDeclaration ::
-  //   'function' '*' Identifier '(' FormalParameterListopt ')'
-  //      '{' FunctionBody '}'
-  Expect(Token::FUNCTION, CHECK_OK);
-  int pos = position();
-  bool is_generator = Check(Token::MUL);
+PreParser::Statement PreParser::ParseHoistableDeclaration(
+    int pos, bool is_generator, bool* ok) {
   bool is_strict_reserved = false;
   Identifier name = ParseIdentifierOrStrictReservedWord(
       &is_strict_reserved, CHECK_OK);
   ParseFunctionLiteral(name, scanner()->location(),
                        is_strict_reserved ? kFunctionNameIsStrictReserved
                                           : kFunctionNameValidityUnknown,
                        is_generator ? FunctionKind::kGeneratorFunction
                                     : FunctionKind::kNormalFunction,
                        pos, FunctionLiteral::kDeclaration, language_mode(),
                        CHECK_OK);
   return Statement::FunctionDeclaration();
 }
 
 
+PreParser::Statement PreParser::ParseHoistableDeclaration(bool* ok) {
+  // FunctionDeclaration ::
+  //   'function' Identifier '(' FormalParameterListopt ')' '{' FunctionBody '}'
+  // GeneratorDeclaration ::
+  //   'function' '*' Identifier '(' FormalParameterListopt ')'
+  //      '{' FunctionBody '}'
+  Expect(Token::FUNCTION, CHECK_OK);
+  int pos = position();
+  bool is_generator = Check(Token::MUL);
+  return ParseHoistableDeclaration(pos, is_generator, CHECK_OK);
+}
+
+
 PreParser::Statement PreParser::ParseClassDeclaration(bool* ok) {
   Expect(Token::CLASS, CHECK_OK);
 
   int pos = position();
   bool is_strict_reserved = false;
   Identifier name =
       ParseIdentifierOrStrictReservedWord(&is_strict_reserved, CHECK_OK);
   ParseClassLiteral(name, scanner()->location(), is_strict_reserved, pos,
                     CHECK_OK);
   return Statement::Default();
@@ skipping 128 matching lines @@
     *bindings_loc =
         Scanner::Location(bindings_start, scanner()->location().end_pos);
   }
 
   if (num_decl != nullptr) *num_decl = nvars;
   if (is_lexical != nullptr) *is_lexical = lexical;
   if (is_binding_pattern != nullptr) *is_binding_pattern = is_pattern;
   return Statement::Default();
 }
 
+PreParser::Statement PreParser::ParseFunctionDeclaration(bool* ok) {
+  Consume(Token::FUNCTION);
+  int pos = position();
+  bool is_generator = Check(Token::MUL);
+  if (allow_harmony_restrictive_declarations() && is_generator) {
+    PreParserTraits::ReportMessageAt(
+        scanner()->location(),
+        MessageTemplate::kGeneratorInLegacyContext);
+    *ok = false;
+    return Statement::Default();
+  }
+  return ParseHoistableDeclaration(pos, is_generator, ok);
+}
+
 PreParser::Statement PreParser::ParseExpressionOrLabelledStatement(
     AllowLabelledFunctionStatement allow_function, bool* ok) {
   // ExpressionStatement | LabelledStatement ::
   //   Expression ';'
   //   Identifier ':' Statement
 
   switch (peek()) {
     case Token::FUNCTION:
     case Token::LBRACE:
       UNREACHABLE();  // Always handled by the callers.
@@ skipping 564 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8