Restrict FunctionDeclarations in Statement position

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 305 matching lines @@
   //   EmptyStatement
   //   ...
 
   if (peek() == Token::SEMICOLON) {
     Next();
     return Statement::Default();
   }
   return ParseSubStatement(ok);
 }
 
+PreParser::Statement PreParser::ParseScopedStatement(bool legacy, bool* ok) {
+  if (is_strict(language_mode()) || peek() != Token::FUNCTION ||
+      (legacy && allow_harmony_restrictive_declarations())) {
+    return ParseSubStatement(ok);
+  } else {
+    return ParseFunctionDeclaration(CHECK_OK);
+  }
+}
 
 PreParser::Statement PreParser::ParseSubStatement(bool* ok) {
   // Statement ::
   //   Block
   //   VariableStatement
   //   EmptyStatement
   //   ExpressionStatement
   //   IfStatement
   //   IterationStatement
   //   ContinueStatement
@@ skipping 54 matching lines @@
 
     case Token::SWITCH:
       return ParseSwitchStatement(ok);
 
     case Token::THROW:
       return ParseThrowStatement(ok);
 
     case Token::TRY:
       return ParseTryStatement(ok);
 
-    case Token::FUNCTION: {
-      Scanner::Location start_location = scanner()->peek_location();
-      Statement statement = ParseFunctionDeclaration(CHECK_OK);
-      Scanner::Location end_location = scanner()->location();
-      if (is_strict(language_mode())) {
-        PreParserTraits::ReportMessageAt(start_location.beg_pos,
-                                         end_location.end_pos,
-                                         MessageTemplate::kStrictFunction);
-        *ok = false;
-        return Statement::Default();
-      } else {
-        return statement;
-      }
-    }
+    case Token::FUNCTION:
+      // FunctionDeclaration only allowed as a StatementListItem, not in
+      // an arbitrary Statement position. Exceptions such as
+      // ES#sec-functiondeclarations-in-ifstatement-statement-clauses
+      // are handled by calling ParseScopedStatement rather than
+      // ParseSubStatement directly.
+      ReportMessageAt(scanner()->peek_location(),
+                      is_strict(language_mode())
+                          ? MessageTemplate::kStrictFunction
+                          : MessageTemplate::kSloppyFunction);
+      *ok = false;
+      return Statement::Default();
 
     case Token::DEBUGGER:
       return ParseDebuggerStatement(ok);
 
     case Token::VAR:
       return ParseVariableStatement(kStatement, ok);
 
     case Token::CONST:
       // In ES6 CONST is not allowed as a Statement, only as a
       // LexicalDeclaration, however we continue to allow it in sloppy mode for
@@ skipping 267 matching lines @@
   // Even if the expression starts with an identifier, it is not necessarily an
   // identifier. For example, "foo + bar" starts with an identifier but is not
   // an identifier.
   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())) {
+      return ParseFunctionDeclaration(ok);
+    }
     Statement statement = ParseStatement(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.
   }
   // Parsed expression statement.
   // Detect attempts at 'let' declarations in sloppy mode.
   if (!allow_harmony_sloppy_let() && peek() == Token::IDENTIFIER &&
       is_sloppy(language_mode()) && expr.IsIdentifier() &&
       expr.AsIdentifier().IsLet()) {
     ReportMessage(MessageTemplate::kSloppyLexical, NULL);
     *ok = false;
     return Statement::Default();
   }
   ExpectSemicolon(CHECK_OK);
   return Statement::ExpressionStatement(expr);
 }
 
 
 PreParser::Statement PreParser::ParseIfStatement(bool* ok) {
   // IfStatement ::
   //   'if' '(' Expression ')' Statement ('else' Statement)?
 
   Expect(Token::IF, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
-  Statement stat = ParseSubStatement(CHECK_OK);
+  Statement stat = ParseScopedStatement(false, CHECK_OK);
   if (peek() == Token::ELSE) {
     Next();
-    Statement else_stat = ParseSubStatement(CHECK_OK);
+    Statement else_stat = ParseScopedStatement(false, CHECK_OK);
     stat = (stat.IsJumpStatement() && else_stat.IsJumpStatement()) ?
         Statement::Jump() : Statement::Default();
   } else {
     stat = Statement::Default();
   }
   return stat;
 }
 
 
 PreParser::Statement PreParser::ParseContinueStatement(bool* ok) {
@@ skipping 75 matching lines @@
     ReportMessageAt(scanner()->location(), MessageTemplate::kStrictWith);
     *ok = false;
     return Statement::Default();
   }
   Expect(Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
   Scope* with_scope = NewScope(scope_, WITH_SCOPE);
   BlockState block_state(&scope_, with_scope);
-  ParseSubStatement(CHECK_OK);
+  ParseScopedStatement(true, CHECK_OK);
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseSwitchStatement(bool* ok) {
   // SwitchStatement ::
   //   'switch' '(' Expression ')' '{' CaseClause* '}'
 
   Expect(Token::SWITCH, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
@@ skipping 29 matching lines @@
   Expect(Token::RBRACE, ok);
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseDoWhileStatement(bool* ok) {
   // DoStatement ::
   //   'do' Statement 'while' '(' Expression ')' ';'
 
   Expect(Token::DO, CHECK_OK);
-  ParseSubStatement(CHECK_OK);
+  ParseScopedStatement(true, CHECK_OK);
   Expect(Token::WHILE, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, ok);
   if (peek() == Token::SEMICOLON) Consume(Token::SEMICOLON);
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseWhileStatement(bool* ok) {
   // WhileStatement ::
   //   'while' '(' Expression ')' Statement
 
   Expect(Token::WHILE, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
-  ParseSubStatement(ok);
+  ParseScopedStatement(true, ok);
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseForStatement(bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
@@ skipping 31 matching lines @@
 
         if (mode == ForEachStatement::ITERATE) {
           ExpressionClassifier classifier(this);
           ParseAssignmentExpression(true, &classifier, CHECK_OK);
           RewriteNonPattern(&classifier, CHECK_OK);
         } else {
           ParseExpression(true, CHECK_OK);
         }
 
         Expect(Token::RPAREN, CHECK_OK);
-        ParseSubStatement(CHECK_OK);
+        ParseScopedStatement(true, CHECK_OK);
         return Statement::Default();
       }
     } else {
       int lhs_beg_pos = peek_position();
       ExpressionClassifier classifier(this);
       Expression lhs = ParseExpression(false, &classifier, CHECK_OK);
       int lhs_end_pos = scanner()->location().end_pos;
       is_let_identifier_expression =
           lhs.IsIdentifier() && lhs.AsIdentifier().IsLet();
       bool is_for_each = CheckInOrOf(&mode, ok);
@@ skipping 17 matching lines @@
 
         if (mode == ForEachStatement::ITERATE) {
           ExpressionClassifier classifier(this);
           ParseAssignmentExpression(true, &classifier, CHECK_OK);
           RewriteNonPattern(&classifier, CHECK_OK);
         } else {
           ParseExpression(true, CHECK_OK);
         }
 
         Expect(Token::RPAREN, CHECK_OK);
-        ParseSubStatement(CHECK_OK);
+        ParseScopedStatement(true, CHECK_OK);
         return Statement::Default();
       }
     }
   }
 
   // Parsed initializer at this point.
   // Detect attempts at 'let' declarations in sloppy mode.
   if (!allow_harmony_sloppy_let() && peek() == Token::IDENTIFIER &&
       is_sloppy(language_mode()) && is_let_identifier_expression) {
     ReportMessage(MessageTemplate::kSloppyLexical, NULL);
     *ok = false;
     return Statement::Default();
   }
   Expect(Token::SEMICOLON, CHECK_OK);
 
   if (peek() != Token::SEMICOLON) {
     ParseExpression(true, CHECK_OK);
   }
   Expect(Token::SEMICOLON, CHECK_OK);
 
   if (peek() != Token::RPAREN) {
     ParseExpression(true, CHECK_OK);
   }
   Expect(Token::RPAREN, CHECK_OK);
 
-  ParseSubStatement(ok);
+  ParseScopedStatement(true, ok);
   return Statement::Default();
 }
 
 
 PreParser::Statement PreParser::ParseThrowStatement(bool* ok) {
   // ThrowStatement ::
   //   'throw' [no line terminator] Expression ';'
 
   Expect(Token::THROW, CHECK_OK);
   if (scanner()->HasAnyLineTerminatorBeforeNext()) {
@@ skipping 259 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8