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 260 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 ParseOnlyFunctionDeclaration(ok);
   }
 }
 
 PreParser::Statement PreParser::ParseSubStatement(
     AllowLabelledFunctionStatement allow_function, bool* ok) {
   // Statement ::
   //   Block
   //   VariableStatement
   //   EmptyStatement
   //   ExpressionStatement
@@ skipping 247 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::ParseOnlyFunctionDeclaration(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();
+  }
+  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,

[adamk, 2016/04/20 19:09:28]

This is a lot of boilerplate to copy; what if you split the existing
ParseFunctionDeclaration into two, as it is for the Parser? Also consider the
same renaming.

[Dan Ehrenberg, 2016/04/26 22:24:19]

Done

+                       language_mode(), CHECK_OK);
+  return Statement::FunctionDeclaration();
+}
+
 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 17 matching lines @@
   if (starts_with_identifier && expr.IsIdentifier() && peek() == Token::COLON) {
     // Expression is a single identifier, and not, e.g., a parenthesized
     // identifier.
     DCHECK(!expr.AsIdentifier().IsFutureReserved());
     DCHECK(is_sloppy(language_mode()) ||
            !IsFutureStrictReserved(expr.AsIdentifier()));
     Consume(Token::COLON);
     // ES#sec-labelled-function-declarations Labelled Function Declarations
     if (peek() == Token::FUNCTION && is_sloppy(language_mode())) {
       if (allow_function == kAllowLabelledFunctionStatement) {
-        return ParseFunctionDeclaration(ok);
+        return ParseOnlyFunctionDeclaration(ok);
       } else {
         return ParseScopedStatement(true, ok);
       }
     }
     Statement statement =
         ParseStatement(kDisallowLabelledFunctionStatement, ok);
     return statement.IsJumpStatement() ? Statement::Default() : statement;
     // Preparsing is disabled for extensions (because the extension details
     // aren't passed to lazily compiled functions), so we don't
     // accept "native function" in the preparser.
@@ skipping 527 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8