mac: Let mac_sdk default to the oldest available SDK that's at least 10.6

build/mac/find_sdk.py

+#!/usr/bin/env python
+# Copyright (c) 2012 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
+
+"""Prints the best locally available SDK version to standard output."""
+
+
+def main():
+  job = subprocess.Popen(['xcode-select', '-print-path'],

[Mark Mentovai, 2012/07/27 03:31:30]

Didn’t we find that xcode-select wouldn’t be initialized to anything in some
cases? When that happens, do we want to fall back to anything?
/Applications/Xcode.app/Contents/Developer for 4.4+, and /Developer for pre-4.4?

+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.STDOUT)
+  out, err = job.communicate()
+  if job.returncode != 0:
+    print out

[Mark Mentovai, 2012/07/27 03:31:30]

Wouldn’t you especially want to print err (to stderr) in this case?

[Nico, 2012/07/27 18:01:05]

Done.

+    raise Exception('Error %d running xcode-select' % job.returncode)
+  # The Developer folder moved in Xcode 4.3.
+  xcode43_sdk_path = os.path.join(
+      out.rstrip(), 'Platforms/MacOSX.platform/Developer/SDKs')
+  if os.path.isdir(xcode43_sdk_path):
+    sdk_dir = xcode43_sdk_path
+  else:
+    sdk_dir = os.path.join(out.rstrip(), 'SDKs')
+  sdks = [re.findall('MacOSX(10\.\d+)\.sdk', s) for s in os.listdir(sdk_dir)]

[Mark Mentovai, 2012/07/27 03:31:30]

Do you want to anchor the RE at the front and back with ^ and $? I think it’s a
good idea.

[Mark Mentovai, 2012/07/27 03:31:30]

Something in os.listdir(sdk_dir) that doesn’t match the pattern will cause there
to be an empty ([]) element in the sdks list, right? But that’s OK, because the
next line will get rid of those entries, right?

[Nico, 2012/07/27 18:01:05]

Done.

[Nico, 2012/07/27 18:01:05]

Yes.

+  sdks = [s[0] for s in sdks if s]  # [['10.5'], ['10.6']] => ['10.5', '10.6']
+  sdks = [s for s in sdks if s >= '10.6']  # ['10.5', '10.6'] => ['10.6]

[Mark Mentovai, 2012/07/27 03:31:30]

Missing a ' on ['10.6].

[Mark Mentovai, 2012/07/27 03:31:30]

This isn’t really the greatest version comparison.

[Nico, 2012/07/27 18:01:05]

Done.

[Nico, 2012/07/27 18:01:05]

Done.

+  if not sdks:
+    raise Exception('No 10.6+ SDK found')
+  print sdks[0]

[Mark Mentovai, 2012/07/27 03:31:30]

Is there any guarantee of sortedness of SDKs? I don’t think so.

[Nico, 2012/07/27 18:01:05]

Done.

+
+
+if __name__ == '__main__':
+  if sys.platform == 'darwin':

[Mark Mentovai, 2012/07/27 03:31:30]

If you’re going to be conditionalizing when you call this script, you might want
to only call it on Mac, and have it raise an exception when not on Darwin.

[Nico, 2012/07/27 18:01:05]

I think it's easier this way.

+    main()