Auto-generate v8 version based on tags.

tools/push-to-trunk/generate_version.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 Script to set v8's version file to the version given by the latest tag.
 """
 
 
 import os
 import re
 import subprocess
 import sys
 
 
 CWD = os.path.abspath(
     os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
 VERSION_CC = os.path.join(CWD, "src", "version.cc")
 
 def main():
+  if len(sys.argv) != 2:
+    print "Error: Specify the output file path for version.cc"
+    return 1
+  version_out = sys.argv[1]
+  assert os.path.exists(os.path.dirname(version_out))
+
   tag = subprocess.check_output(
       "git describe --tags",
       shell=True,
       cwd=CWD,
   ).strip()
   assert tag
 
   # Check for commits not exactly matching a tag. Those are candidate builds
   # for the next version. The output has the form
   # <tag name>-<n commits>-<hash>.
@@ skipping 24 matching lines @@
   for line in text.split("\n"):
     for definition, substitute in (
         ("MAJOR_VERSION", major),
         ("MINOR_VERSION", minor),
         ("BUILD_NUMBER", build),
         ("PATCH_LEVEL", patch),
         ("IS_CANDIDATE_VERSION", candidate)):
       if line.startswith("#define %s" % definition):
         line =  re.sub("\d+$", substitute, line)
     output.append(line)
-  with open(VERSION_CC, "w") as f:
+  with open(version_out, "w") as f:
     f.write("\n".join(output))
 
   # Log what was done.
   candidate_txt = " (candidate)" if candidate == "1" else ""
   patch_txt = ".%s" % patch if patch != "0" else ""
   version_txt = ("%s.%s.%s%s%s" %
                  (major, minor, build, patch_txt, candidate_txt))
   print "Modified version.cc. Set V8 version to %s" %  version_txt
   return 0
 
 if __name__ == "__main__":
   sys.exit(main())