Add support for GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO to xcode emulation.

test/mac/gyptest-xcode-gcc.py

+#!/usr/bin/env python
+
+# Copyright (c) 2012 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+Verifies that xcode-style GCC_... settings are handled properly.
+"""
+
+import TestGyp
+
+import sys
+
+def IgnoreOutput(string, expected_string):
+  return True
+
+if sys.platform == 'darwin':
+  test = TestGyp.TestGyp(formats=['ninja', 'make', 'xcode'])
+
+  CHDIR = 'xcode-gcc'
+  test.run_gyp('test.gyp', chdir=CHDIR)
+
+  # List of targets that'll pass. It expects targets of the same name with
+  # '-fail' appended that'll fail to build.
+  targets = [
+    'warn_about_invalid_offsetof_macro',
+    'warn_about_missing_newline',
+  ]
+
+  for target in targets:
+    test.build('test.gyp', target, chdir=CHDIR)
+    test.built_file_must_exist(target, chdir=CHDIR)
+    fail_target = target + '-fail'
+    test.build('test.gyp', fail_target, chdir=CHDIR, status=None,
+               stderr=None, match=IgnoreOutput)
+    test.built_file_must_not_exist(fail_target, chdir=CHDIR)
+
+  test.pass_test()