gn: Enforce braces after 'else'

tools/gn/parser.cc

 // Copyright (c) 2013 The Chromium 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 "tools/gn/parser.h"
 
 #include "base/logging.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/operators.h"
 #include "tools/gn/token.h"
@@ skipping 481 matching lines @@
 
 scoped_ptr<ParseNode> Parser::ParseCondition() {
   scoped_ptr<ConditionNode> condition(new ConditionNode);
   condition->set_if_token(Consume(Token::IF, "Expected 'if'"));
   Consume(Token::LEFT_PAREN, "Expected '(' after 'if'.");
   condition->set_condition(ParseExpression());
   if (IsAssignment(condition->condition()))
     *err_ = Err(condition->condition(), "Assignment not allowed in 'if'.");
   Consume(Token::RIGHT_PAREN, "Expected ')' after condition of 'if'.");
   condition->set_if_true(ParseBlock().Pass());
-  if (Match(Token::ELSE))
+  if (Match(Token::ELSE)) {
+    if (!LookAhead(Token::LEFT_BRACE) && !LookAhead(Token::IF)) {

[tfarina, 2015/03/10 20:37:24]

|| here does the wrong thing?

Anyway, thanks for figuring out this!

[scottmg, 2015/03/10 21:21:00]

I'm not sure what you mean. Right now it says "if it's not a left brace, and
it's not an if" then error out. An "or" there would always go into the error
condition because it can only be one of those two things.
 

+      *err_ = Err(cur_token(), "Expected '{' or 'if' after 'else'.");
+      return scoped_ptr<ParseNode>();

[tfarina, 2015/03/10 20:37:24]

This can be return nullptr;

[scottmg, 2015/03/10 21:21:00]

There's a whole bunch that predate nullptr in this file. I don't want to change
them all in this CL, so I'm going to leave it like this and they can all be
changed together separately.

+    }
     condition->set_if_false(ParseStatement().Pass());
+  }
   if (has_error())
     return scoped_ptr<ParseNode>();
   return condition.Pass();
 }
 
 void Parser::TraverseOrder(const ParseNode* root,
                            std::vector<const ParseNode*>* pre,
                            std::vector<const ParseNode*>* post) {
   if (root) {
     pre->push_back(root);
@@ skipping 96 matching lines @@
         break;
       }
     }
 
     // Suffix comments were assigned in reverse, so if there were multiple on
     // the same node, they need to be reversed.
     if ((*i)->comments() && !(*i)->comments()->suffix().empty())
       const_cast<ParseNode*>(*i)->comments_mutable()->ReverseSuffix();
   }
 }