Create a "no compile" drivers script in python to unittest compile time asserts.

build/nocompile.gypi

Index: build/nocompile.gypi
diff --git a/build/nocompile.gypi b/build/nocompile.gypi
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+# Copyright (c) 2011 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.
+
+# This file is meant to be included into an target to create a unittest that
+# invokes a set of no-compile tests.  A no-compile test is a test that asserts
+# a particular construct will not compile.
+#
+# Also see:
+#   http://dev.chromium.org/developers/testing/no-compile-tests
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_module_nc_unittests',
+#   'type': 'executable',
+#   'sources': [
+#     'nc_testset_1.nc',
+#     'nc_testset_2.nc',
+#   ],
+#   'includes': ['path/to/this/gypi/file'],
+# }
+#
+# The .nc files are C++ files that contain code we wish to assert will not
+# compile.  Each individual test case in the file should be put in its own
+# #ifdef section.  The expected output should be appended with a C++-style
+# comment that has a python list of regular expressions.  This will likely
+# be greater than 80-characters. Giving a solid expected output test is
+# important so that random compile failures do not cause the test to pass.
+#
+# Example .nc file:
+#
+#   #if defined(TEST_NEEDS_SEMICOLON)  // [r"expected ',' or ';' at end of input"]
+#
+#   int a = 1
+#
+#   #elif defined(TEST_NEEDS_CAST)  // [r"invalid conversion from 'void*' to 'char*'"]
+#
+#   void* a = NULL;
+#   char* b = a;
+#
+#   #endif
+#
+# If we needed disable TEST_NEEDS_SEMICOLON, then change the define to:
+#
+#   DISABLE_TEST_NEEDS_SEMICOLON
+#   TEST_NEEDS_CAST
+#
+# The lines above are parsed by a regexp so avoid getting creative with the
+# formatting or ifdef logic; it will likely just not work.
+#
+# Implementation notes:
+# The .nc files are actually processed by a python script which executes the
+# compiler and generates a .cc file that is empty on success, or will have a
+# series of #error lines on failure, and a set of trivially passing gunit
+# TEST() functions on success. This allows us to fail at the compile step when
+# something goes wrong, and know during the unittest run that the test was at
+# least processed when things go right.
+
+{
+  'conditions': [
+    [ 'OS=="linux" and clang==0', {
+      'rules': [
+        {
+          'variables': {
+            'nocompile_driver': '<(DEPTH)/tools/nocompile_driver.py',
+            'nc_result_path': ('<(INTERMEDIATE_DIR)/<(module_dir)/'
+                               '<(RULE_INPUT_ROOT)_nc.cc'),
+           },
+          'rule_name': 'run_nocompile',
+          'extension': 'nc',
+          'inputs': [
+            '<(nocompile_driver)',
+          ],
+          'outputs': [
+            '<(nc_result_path)'
+          ],
+          'action': [
+            'python',
+            '<(nocompile_driver)',
+            '4', # number of compilers to invoke in parallel.
+            '<(RULE_INPUT_PATH)',
+            '-Wall -Werror -Wfatal-errors -I<(DEPTH)',
+            '<(nc_result_path)',
+            ],
+          'message': 'Generating no compile results for <(RULE_INPUT_PATH)',
+          'process_outputs_as_sources': 1,
+        },
+      ],
+    }, {
+      'sources/': [['exclude', '\\.nc$']]
+    }],  # 'OS=="linux" and clang=="0"'
+  ],
+}
+