Add clang_version.py, heavily based on compiler_version.py so we

can detect when we're using clang, and also its version.

build/clang_version.py

@@ -0,0 +1,57 @@
+#!/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.
+#
+
+"""Compiler version checking tool for clang.
+
+(Based on corresponding tool for gcc in Chromium build system).
+
+Prints X*100 + Y if $CXX is pointing to clang X.Y.*. Prints 0 otherwise.
+Note that this output convention is different from compiler_version.py's. This
+also never returns a failing status, since we want to run this even on systems
+without clang, and gyp will complain on a non-successful status.
+"""
+
+import os
+import re
+import subprocess
+import sys
+
+
+def GetVersion(compiler):
+  try:
+    compiler = compiler + " --version"
+    pipe = subprocess.Popen(compiler, shell=True,
+                            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    output, error = pipe.communicate()
+    if pipe.returncode:
+      raise subprocess.CalledProcessError(pipe.returncode, compiler)
+
+    result = re.search(r"clang version (\d+)\.?(\d+)?", output)
+    if result is None:
+      return "0"
+    minor_version = result.group(2)
+    if minor_version is None:
+      minor_version = "0"
+    return str(int(result.group(1)) * 100 + int(minor_version))
+  except Exception, e:
+    if error:
+      sys.stderr.write(error)
+    print >> sys.stderr, "clang_version.py failed to execute:", compiler
+    print >> sys.stderr, e
+    return "0"
+
+
+def main():
+  # Check if CXX environment variable exists, and if it does use that compiler.
+  cxx = os.getenv("CXX", None)
+  if cxx:
+    print GetVersion(cxx)
+  else:
+    print "0"
+
+if __name__ == "__main__":
+  main()
+  sys.exit(0)