[Mac/iOS/GN] Add //build/toolchain/mac/filter_libtool.py.

build/toolchain/mac/filter_libtool.py

+# Copyright 2016 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.
+
+import os
+import re
+import subprocess
+import sys
+
+# This script executes libool and filters out logspam lines like:
+#    '/path/to/libtool: file: foo.o has no symbols'
+
+def Main(cmd_list):
+  libtool_re = re.compile(r'^.*libtool: (?:for architecture: \S* )?'
+                          r'file: .* has no symbols$')
+  libtool_re5 = re.compile(
+      r'^.*libtool: warning for library: ' +
+      r'.* the table of contents is empty ' +
+      r'\(no object file members in the library define global symbols\)$')
+  env = os.environ.copy()
+  # Ref:
+  # http://www.opensource.apple.com/source/cctools/cctools-809/misc/libtool.c
+  # The problem with this flag is that it resets the file mtime on the file to
+  # epoch=0, e.g. 1970-1-1 or 1969-12-31 depending on timezone.
+  env['ZERO_AR_DATE'] = '1'
+  libtoolout = subprocess.Popen(cmd_list, stderr=subprocess.PIPE, env=env)
+  _, err = libtoolout.communicate()
+  for line in err.splitlines():
+    if not libtool_re.match(line) and not libtool_re5.match(line):
+      print >>sys.stderr, line
+  # Unconditionally touch the output .a file on the command line if present
+  # and the command succeeded. A bit hacky.
+  if not libtoolout.returncode:
+    for i in range(len(cmd_list) - 1):
+      if cmd_list[i] == '-o' and cmd_list[i+1].endswith('.a'):
+        os.utime(cmd_list[i+1], None)
+        break
+  return libtoolout.returncode
+
+
+if __name__ == '__main__':
+  sys.exit(Main(sys.argv[1:]))