gn/win: Don't strip trailing = on exec_script arguments.

tools/gn/function_exec_script.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 "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
@@ skipping 153 matching lines @@
               dep, err,
               scope->settings()->build_settings()->root_path_utf8())));
       if (err->has_error())
         return Value();
     }
   }
 
   // Make the command line.
   const base::FilePath& python_path = build_settings->python_path();
   base::CommandLine cmdline(python_path);
+
+  // Opt out of CommandLine's parameter processing, which reformats switches
+  // and so on.  For GN, arguments should be passed on exactly like they are
+  // in the .gn file.
+  cmdline.AppendArg("--");

[brettw, 2016/02/22 22:32:45]

I'm confused, won't this pass "--" to Python as well. Or is that OK? If we're
doing that on purpose I'd mention it explicitly, since it's not "exactly whats
in the .gn file".

[Nico, 2016/02/22 22:58:05]

base/command_kind.cc filters out the first -- parameter...it has a somewhat
magic API here.

[brettw, 2016/02/22 23:00:35]

Weird, base::CommandLine is a disaster. Can you mention this in the comment.

+
   cmdline.AppendArgPath(script_path);
 
+

[brettw, 2016/02/22 22:32:45]

Looks like you got an extra line in here.

[Nico, 2016/02/22 22:58:05]

Will remove

   if (args.size() >= 2) {
     // Optional command-line arguments to the script.
     const Value& script_args = args[1];
     if (!script_args.VerifyTypeIs(Value::LIST, err))
       return Value();
     for (const auto& arg : script_args.list_value()) {
       if (!arg.VerifyTypeIs(Value::STRING, err))
         return Value();
       cmdline.AppendArg(arg.string_value());
     }
@@ skipping 56 matching lines @@
                msg);
     return Value();
   }
 
   // Default to None value for the input conversion if unspecified.
   return ConvertInputToValue(scope->settings(), output, function,
                              args.size() >= 3 ? args[2] : Value(), err);
 }
 
 }  // namespace functions