Revert of Use Clang's update.py --print-revision everywhere.

tools/clang/scripts/update.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.
 
 """Windows can't run .sh files, so this is a Python implementation of
 update.sh. This script should replace update.sh on all platforms eventually."""
 
 import argparse
 import os
@@ skipping 47 matching lines @@
 def WriteStampFile(s):
   """Write s to the stamp file."""
   if not os.path.exists(LLVM_BUILD_DIR):
     os.makedirs(LLVM_BUILD_DIR)
   with open(STAMP_FILE, 'w') as f:
     f.write(s)
 
 
 def PrintRevision():
   """Print the current Clang revision."""
-  # gyp runs update.py --print-revision even when clang=1 isn't set.
-  # It won't use the value, but we must not error.
-  if not re.search(r'\b(clang|asan)=1', os.environ.get('GYP_DEFINES', '')):
-    print "0"
-    return
-
   # TODO(hans): This needs an update when we move to prebuilt Clang binaries.
   svn_info = subprocess.check_output(['svn', 'info', LLVM_DIR])
   m = re.search(r'Revision: (\d+)', svn_info)
   assert m
   print m.group(1)
 
 
 def RmTree(dir):
   """Delete dir."""
   def ChmodAndRetry(func, path, _):
     # Subversion can leave read-only files around.
     if not os.access(path, os.W_OK):
       os.chmod(path, stat.S_IWUSR)
       return func(path)
     raise
 
   shutil.rmtree(dir, onerror=ChmodAndRetry)
 
 
+def ClobberChromiumBuildFiles():
+  """Clobber Chomium build files."""
+  print 'Clobbering Chromium build files...'
+  out_dir = os.path.join(CHROMIUM_DIR, 'out')
+  if os.path.isdir(out_dir):
+    RmTree(out_dir)
+    print 'Removed Chromium out dir: %s.' % (out_dir)
+
+
 def RunCommand(command, fail_hard=True):
   """Run command and return success (True) or failure; or if fail_hard is
      True, exit on failure."""
 
   print 'Running %s' % (str(command))
   if subprocess.call(command, shell=True) == 0:
     return True
   print 'Failed.'
   if fail_hard:
     sys.exit(1)
@@ skipping 112 matching lines @@
   return ''
 
 
 def UpdateClang(args):
   print 'Updating Clang to %s...' % (LLVM_WIN_REVISION)
   if LLVM_WIN_REVISION != 'HEAD' and ReadStampFile() == LLVM_WIN_REVISION:
     print 'Already up to date.'
     return 0
 
   AddCMakeToPath()
+  if args.clobber:
+    ClobberChromiumBuildFiles()
+
   # Reset the stamp file in case the build is unsuccessful.
   WriteStampFile('')
 
   DeleteChromeToolsShim();
   Checkout('LLVM', LLVM_REPO_URL + '/llvm/trunk', LLVM_DIR)
   Checkout('Clang', LLVM_REPO_URL + '/cfe/trunk', CLANG_DIR)
   Checkout('LLD', LLVM_REPO_URL + '/lld/trunk', LLD_DIR)
   Checkout('compiler-rt', LLVM_REPO_URL + '/compiler-rt/trunk', COMPILER_RT_DIR)
   CreateChromeToolsShim();
 
@@ skipping 60 matching lines @@
 
     # This script is called by gclient. gclient opens its hooks subprocesses
     # with (stdout=subprocess.PIPE, stderr=subprocess.STDOUT) and then does
     # custom output processing that breaks printing '\r' characters for
     # single-line updating status messages as printed by curl and wget.
     # Work around this by setting stderr of the update.sh process to stdin (!):
     # gclient doesn't redirect stdin, and while stdin itself is read-only, a
     # dup()ed sys.stdin is writable, try
     #   fd2 = os.dup(sys.stdin.fileno()); os.write(fd2, 'hi')
     # TODO: Fix gclient instead, http://crbug.com/95350
-    try:
-      stderr = os.fdopen(os.dup(sys.stdin.fileno()))
-    except:
-      stderr = sys.stderr
     return subprocess.call(
-        [os.path.join(os.path.dirname(__file__), 'update.sh')] + sys.argv[1:],
-        stderr=stderr)
+        [os.path.join(os.path.dirname(__file__), 'update.sh')] +  sys.argv[1:],
+        stderr=os.fdopen(os.dup(sys.stdin.fileno())))
 
   parser = argparse.ArgumentParser(description='Build Clang.')
+  parser.add_argument('--no-clobber', dest='clobber', action='store_false')
   parser.add_argument('--tools', nargs='*', default=['plugins'])
   # For now, this flag is only used for the non-Windows flow, but argparser gets
   # mad if it sees a flag it doesn't recognize.
   parser.add_argument('--if-needed', action='store_true')
   parser.add_argument('--print-revision', action='store_true')
 
   args = parser.parse_args()
 
   if args.print_revision:
     PrintRevision()
     return 0
 
   if not re.search(r'\b(clang|asan)=1', os.environ.get('GYP_DEFINES', '')):
     print 'Skipping Clang update (clang=1 was not set in GYP_DEFINES).'
     return 0
 
   if re.search(r'\b(make_clang_dir)=', os.environ.get('GYP_DEFINES', '')):
     print 'Skipping Clang update (make_clang_dir= was set in GYP_DEFINES).'
     return 0
 
   return UpdateClang(args)
 
 
 if __name__ == '__main__':
   sys.exit(main())