Update from https://crrev.com/327068

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
 import re
 import shutil
 import subprocess
 import stat
 import sys
 import time
 
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://code.google.com/p/chromium/wiki/UpdatingClang
 # Reverting problematic clang rolls is safe, though.
 # Note: this revision is only used for Windows. Other platforms use update.sh.
 LLVM_WIN_REVISION = 'HEAD'
 
 # ASan on Windows is useful enough to use it even while the clang/win is still
 # in bringup. Use a pinned revision to make it slightly more stable.
 if (re.search(r'\b(asan)=1', os.environ.get('GYP_DEFINES', '')) and
     not 'LLVM_FORCE_HEAD_REVISION' in os.environ):
-  LLVM_WIN_REVISION = '232554'
+  LLVM_WIN_REVISION = '235793'
 
 # Path constants. (All of these should be absolute paths.)
 THIS_DIR = os.path.abspath(os.path.dirname(__file__))
 CHROMIUM_DIR = os.path.abspath(os.path.join(THIS_DIR, '..', '..', '..'))
 LLVM_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'llvm')
+CHROME_TOOLS_SHIM_DIR = os.path.join(LLVM_DIR, 'tools', 'chrometools')
 LLVM_BUILD_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'llvm-build',
                               'Release+Asserts')
 COMPILER_RT_BUILD_DIR = os.path.join(LLVM_BUILD_DIR, '32bit-compiler-rt')
 CLANG_DIR = os.path.join(LLVM_DIR, 'tools', 'clang')
 LLD_DIR = os.path.join(LLVM_DIR, 'tools', 'lld')
 COMPILER_RT_DIR = os.path.join(LLVM_DIR, 'projects', 'compiler-rt')
 STAMP_FILE = os.path.join(LLVM_BUILD_DIR, 'cr_build_revision')
 VERSION = '3.7.0'
 
 LLVM_REPO_URL='https://llvm.org/svn/llvm-project'
@@ skipping 79 matching lines @@
     return
 
   if os.path.isdir(dir):
     print "Removing %s." % (dir)
     RmTree(dir)
 
   print "Retrying."
   RunCommand(command)
 
 
+def DeleteChromeToolsShim():
+  shutil.rmtree(CHROME_TOOLS_SHIM_DIR, ignore_errors=True)
+
+
+def CreateChromeToolsShim():
+  """Hooks the Chrome tools into the LLVM build.
+
+  Several Chrome tools have dependencies on LLVM/Clang libraries. The LLVM build
+  detects implicit tools in the tools subdirectory, so this helper install a
+  shim CMakeLists.txt that forwards to the real directory for the Chrome tools.
+
+  Note that the shim directory name intentionally has no - or _. The implicit
+  tool detection logic munges them in a weird way."""
+  assert not any(i in os.path.basename(CHROME_TOOLS_SHIM_DIR) for i in '-_')
+  os.mkdir(CHROME_TOOLS_SHIM_DIR)
+  with file(os.path.join(CHROME_TOOLS_SHIM_DIR, 'CMakeLists.txt'), 'w') as f:
+    f.write('# Automatically generated by tools/clang/scripts/update.py. ' +
+            'Do not edit.\n')
+    f.write('# Since tools/clang is located in another directory, use the \n')
+    f.write('# two arg version to specify where build artifacts go. CMake\n')
+    f.write('# disallows reuse of the same binary dir for multiple source\n')
+    f.write('# dirs, so the build artifacts need to go into a subdirectory.\n')
+    f.write('add_subdirectory(${CHROMIUM_TOOLS_SRC} ' +
+            '${CMAKE_CURRENT_BINARY_DIR}/a)\n')
+
+
 def AddCMakeToPath():
   """Look for CMake and add it to PATH if it's not there already."""
   try:
     # First check if cmake is already on PATH.
     subprocess.call(['cmake', '--version'])
     return
   except OSError as e:
     if e.errno != os.errno.ENOENT:
       raise
 
@@ skipping 32 matching lines @@
   # svn.bat in depot_tools will be ignored.
   default_pathext = ('.com', '.exe', '.bat', '.cmd')
   for path in os.environ.get('PATH', '').split(os.pathsep):
     for ext in default_pathext:
       candidate = os.path.join(path, 'svn' + ext)
       if os.path.isfile(candidate):
         return '-DSubversion_SVN_EXECUTABLE=%s' % candidate
   return ''
 
 
-def UpdateClang():
+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()
-  ClobberChromiumBuildFiles()
+  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();
 
   if not os.path.exists(LLVM_BUILD_DIR):
     os.makedirs(LLVM_BUILD_DIR)
   os.chdir(LLVM_BUILD_DIR)
 
+  cmake_args = ['-GNinja', '-DCMAKE_BUILD_TYPE=Release',
+                '-DLLVM_ENABLE_ASSERTIONS=ON', SubversionCmakeArg(),
+                '-DCHROMIUM_TOOLS_SRC=%s' % os.path.join(
+                    CHROMIUM_DIR, 'tools', 'clang'),
+                '-DCHROMIUM_TOOLS=%s' % ';'.join(args.tools)]
+
   RunCommand(GetVSVersion().SetupScript('x64') +
-             ['&&', 'cmake', '-GNinja', '-DCMAKE_BUILD_TYPE=Release',
-              '-DLLVM_ENABLE_ASSERTIONS=ON', SubversionCmakeArg(), LLVM_DIR])
+             ['&&', 'cmake'] + cmake_args + [LLVM_DIR])
   RunCommand(GetVSVersion().SetupScript('x64') + ['&&', 'ninja', 'all'])
 
   # Do an x86 build of compiler-rt to get the 32-bit ASan run-time.
   # TODO(hans): Remove once the regular build above produces this.
   if not os.path.exists(COMPILER_RT_BUILD_DIR):
     os.makedirs(COMPILER_RT_BUILD_DIR)
   os.chdir(COMPILER_RT_BUILD_DIR)
   RunCommand(GetVSVersion().SetupScript('x86') +
-             ['&&', 'cmake', '-GNinja', '-DCMAKE_BUILD_TYPE=Release',
-              '-DLLVM_ENABLE_ASSERTIONS=ON', LLVM_DIR])
+             ['&&', 'cmake'] + cmake_args + [LLVM_DIR])
   RunCommand(GetVSVersion().SetupScript('x86') + ['&&', 'ninja', 'compiler-rt'])
 
   # TODO(hans): Make this (and the .gypi and .isolate files) version number
   # independent.
   asan_rt_lib_src_dir = os.path.join(COMPILER_RT_BUILD_DIR, 'lib', 'clang',
                                      VERSION, 'lib', 'windows')
   asan_rt_lib_dst_dir = os.path.join(LLVM_BUILD_DIR, 'lib', 'clang',
                                      VERSION, 'lib', 'windows')
   CopyDirectoryContents(asan_rt_lib_src_dir, asan_rt_lib_dst_dir,
                         r'^.*-i386\.lib$')
@@ skipping 41 matching lines @@
         stderr=os.fdopen(os.dup(sys.stdin.fileno())))
 
   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()
+  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')
+  return UpdateClang(parser.parse_args())
 
 
 if __name__ == '__main__':
   sys.exit(main())