build-support/iwyu/iwyu_tool.py - kudu - Git at Google

 #!/usr/bin/env python

 # This file has been imported into the Kudu source tree from
 # the IWYU source tree as of version 0.8
 #   https://github.com/include-what-you-use/include-what-you-use/blob/master/iwyu_tool.py
 # and corresponding license has been added:
 #   https://github.com/include-what-you-use/include-what-you-use/blob/master/LICENSE.TXT
 #
 # ------------------------------------------------------------------------------
 # NOTE: some local Kudu modifications have been made. Before
 # "upgrading" this to a new version from upstream, check the git log.
 # ------------------------------------------------------------------------------
 #
 # ==============================================================================
 # LLVM Release License
 # ==============================================================================
 # University of Illinois/NCSA
 # Open Source License
 #
 # Copyright (c) 2003-2010 University of Illinois at Urbana-Champaign.
 # All rights reserved.
 #
 # Developed by:
 #
 #     LLVM Team
 #
 #     University of Illinois at Urbana-Champaign
 #
 #     http://llvm.org
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy of
 # this software and associated documentation files (the "Software"), to deal with
 # the Software without restriction, including without limitation the rights to
 # use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 # of the Software, and to permit persons to whom the Software is furnished to do
 # so, subject to the following conditions:
 #
 #     * Redistributions of source code must retain the above copyright notice,
 #       this list of conditions and the following disclaimers.
 #
 #     * Redistributions in binary form must reproduce the above copyright notice,
 #       this list of conditions and the following disclaimers in the
 #       documentation and/or other materials provided with the distribution.
 #
 #     * Neither the names of the LLVM Team, University of Illinois at
 #       Urbana-Champaign, nor the names of its contributors may be used to
 #       endorse or promote products derived from this Software without specific
 #       prior written permission.
 #
 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 # FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 # CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
 # SOFTWARE.

 """ Driver to consume a Clang compilation database and invoke IWYU.

 Example usage with CMake:

   # Unix systems
   $ mkdir build && cd build
   $ CC="clang" CXX="clang++" cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ...
   $ iwyu_tool.py -p .

   # Windows systems
   $ mkdir build && cd build
   $ cmake -DCMAKE_CXX_COMPILER="%VCINSTALLDIR%/bin/cl.exe" \
     -DCMAKE_C_COMPILER="%VCINSTALLDIR%/VC/bin/cl.exe" \
     -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
     -G Ninja ...
   $ python iwyu_tool.py -p .

 See iwyu_tool.py -h for more details on command-line arguments.
 """

 import argparse
 import glob
 import json
 import multiprocessing
 from multiprocessing.pool import ThreadPool
 import os
 import re
 import subprocess
 import sys
 import unittest
 sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
 from kudu_util import get_thirdparty_dir


 def iwyu_formatter(output):
     """ Process iwyu's output, basically a no-op. """
     print('\n'.join(output))


 CORRECT_RE = re.compile(r'^\((.*?) has correct #includes/fwd-decls\)$')
 SHOULD_ADD_RE = re.compile(r'^(.*?) should add these lines:$')
 SHOULD_REMOVE_RE = re.compile(r'^(.*?) should remove these lines:$')
 FULL_LIST_RE = re.compile(r'The full include-list for (.*?):$')
 END_RE = re.compile(r'^---$')
 LINES_RE = re.compile(r'^- (.*?)  // lines ([0-9]+)-[0-9]+$')


 GENERAL, ADD, REMOVE, LIST = range(4)


 def clang_formatter(output):
     """ Process iwyu's output into something clang-like. """
     state = (GENERAL, None)
     for line in output:
         match = CORRECT_RE.match(line)
         if match:
             print('%s:1:1: note: #includes/fwd-decls are correct' % match.groups(1))
             continue
         match = SHOULD_ADD_RE.match(line)
         if match:
             state = (ADD, match.group(1))
             continue
         match = SHOULD_REMOVE_RE.match(line)
         if match:
             state = (REMOVE, match.group(1))
             continue
         match = FULL_LIST_RE.match(line)
         if match:
             state = (LIST, match.group(1))
         elif END_RE.match(line):
             state = (GENERAL, None)
         elif not line.strip():
             continue
         elif state[0] == GENERAL:
             print(line)
         elif state[0] == ADD:
             print('%s:1:1: error: add the following line' % state[1])
             print(line)
         elif state[0] == REMOVE:
             match = LINES_RE.match(line)
             line_no = match.group(2) if match else '1'
             print('%s:%s:1: error: remove the following line' % (state[1], line_no))
             print(match.group(1))


 DEFAULT_FORMAT = 'iwyu'
 FORMATTERS = {
     'iwyu': iwyu_formatter,
     'clang': clang_formatter
 }

 def get_output(cwd, args):
     """ Run the given command and return its output as a string. """
     process = subprocess.Popen(args=args,
                                cwd=cwd,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.STDOUT)
     return process.communicate()[0].decode("utf-8").splitlines()


 def run_iwyu(cwd, compile_command, iwyu_args, verbose):
     """ Rewrite compile_command to an IWYU command, and run it. """
     compiler, _, args = compile_command.partition(' ')
     if compiler.endswith('cl.exe'):
         # If the compiler name is cl.exe, let IWYU be cl-compatible
         clang_args = ['--driver-mode=cl']
     else:
         clang_args = []

     extra_args = []
     for a in iwyu_args:
         extra_args += ['-Xiwyu', a]

     cmd_args = ['include-what-you-use'] + clang_args + extra_args + args.split()

     if verbose:
         print('{0}'.format(cmd_args))

     return get_output(cwd, cmd_args)


 def workaround_parent_dir_relative_includes(cwd, command):
     """
     Replace any relative include paths in the compilation command
     'command' with the appropriate absolute paths.

     This works around an apparent bug in IWYU in which passing relative
     paths like -I../../src/ result in IWYU not reporting issues that it
     otherwise would report when the corresponding absolute path is
     passed.

     Oddly enough, this is only relevant when using the Ninja generator
     for CMake, which results in relative paths in the -I directives. The
     Makefile generator always produces absolute paths to begin with.
     See https://gitlab.kitware.com/cmake/cmake/issues/17450
     """
     def subber(m):
         return m.group(1) + os.path.abspath(os.path.join(cwd, m.group(2)))
     return re.sub(r'(-isystem |-I\s*)([^/\s]\S+)', subber, command)


 class RelativeIncludeTest(unittest.TestCase):
     def test(self):
         f = workaround_parent_dir_relative_includes
         self.assertEquals(f('/foo/bar', 'gcc -isystem relative/dir'),
                           'gcc -isystem /foo/bar/relative/dir')
         self.assertEquals(f('/foo/bar', 'gcc -I relative/dir'),
                           'gcc -I /foo/bar/relative/dir')
         self.assertEquals(f('/foo/bar', 'gcc -Irelative/dir'),
                           'gcc -I/foo/bar/relative/dir')

         self.assertEquals(f('/foo/bar', 'gcc -isystem /abs/dir'),
                           'gcc -isystem /abs/dir')
         self.assertEquals(f('/foo/bar', 'gcc -I /abs/dir'),
                           'gcc -I /abs/dir')
         self.assertEquals(f('/foo/bar', 'gcc -I/abs/dir'),
                           'gcc -I/abs/dir')

 def workaround_add_libcpp(build_dir, command):
     """
     Modify 'command' to include C++ standard library headers from the libc++
     found in Kudu's thirdparty tree.

     By default, IWYU will use the system's libstdc++ for standard library
     headers. This is problematic as every system has a different version of
     libstdc++, leading to differing recommendations depending on the host system.

     If we standardize on libc++ from Kudu's thirdparty tree, we can ensure the
     same recommendations regardless of system, though those recommendations will
     change when libc++ is upgraded.
     """
     nostdinc = "-nostdinc++"
     if nostdinc not in command:
         command += " " + nostdinc

     # Check for and add any dynamic (path-based) flags.
     #
     # Some sanitizer builds (like TSAN) already include libc++; if the command
     # already has a flag including libc++, we don't want to add it again.
     path_to_libcpp_prefix = os.path.join(get_thirdparty_dir(), "installed")
     path_to_libcpp_suffix = os.path.join("include", "c++", "v1")
     tp_pattern = os.path.join(path_to_libcpp_prefix, "*", path_to_libcpp_suffix)
     found = False
     for path in glob.glob(tp_pattern):
         search_string = "-isystem " + path
         if search_string in command:
             found = True
             break
     if not found:
         path_to_libcpp = os.path.join(path_to_libcpp_prefix, "uninstrumented",
                                       path_to_libcpp_suffix)
         command += " -isystem " + os.path.abspath(path_to_libcpp)

     return command

 def main(compilation_db_path, source_files, verbose, formatter, iwyu_args):
     """ Entry point. """
     # Canonicalize compilation database path
     if os.path.isdir(compilation_db_path):
         compilation_db_path = os.path.join(compilation_db_path,
                                            'compile_commands.json')

     compilation_db_path = os.path.realpath(compilation_db_path)
     if not os.path.isfile(compilation_db_path):
         print('ERROR: No such file or directory: \'%s\'' % compilation_db_path)
         return 1

     # Read compilation db from disk
     with open(compilation_db_path, 'r') as fileobj:
         compilation_db = json.load(fileobj)

     # expand symlinks
     for entry in compilation_db:
         entry['file'] = os.path.realpath(entry['file'])

     # Cross-reference source files with compilation database
     source_files = [os.path.realpath(s) for s in source_files]
     if not source_files:
         # No source files specified, analyze entire compilation database
         entries = compilation_db
     else:
         # Source files specified, analyze the ones appearing in compilation db,
         # warn for the rest.
         entries = []
         for source in source_files:
             matches = [e for e in compilation_db if e['file'] == source]
             if matches:
                 entries.extend(matches)
             else:
                 print('WARNING: \'%s\' not found in compilation database.' %
                       source)

     # Run analysis
     build_dir = os.path.dirname(compilation_db_path)
     def run_iwyu_task(entry):
         cwd, compile_command = entry['directory'], entry['command']
         compile_command = workaround_parent_dir_relative_includes(
             cwd, compile_command)
         compile_command = workaround_add_libcpp(build_dir, compile_command)
         return run_iwyu(cwd, compile_command, iwyu_args, verbose)
     pool = ThreadPool(multiprocessing.cpu_count())
     try:
         for iwyu_output in pool.imap_unordered(run_iwyu_task, entries):
             formatter(iwyu_output)
     except KeyboardInterrupt as ki:
         sys.exit(1)
     except OSError as why:
         print('ERROR: Failed to launch include-what-you-use: %s' % why)
         return 1
     finally:
         pool.terminate()
         pool.join()
     return 0


 def _bootstrap():
     """ Parse arguments and dispatch to main(). """
     # This hackery is necessary to add the forwarded IWYU args to the
     # usage and help strings.
     def customize_usage(parser):
         """ Rewrite the parser's format_usage. """
         original_format_usage = parser.format_usage
         parser.format_usage = lambda: original_format_usage().rstrip() + \
                               ' -- [<IWYU args>]' + os.linesep

     def customize_help(parser):
         """ Rewrite the parser's format_help. """
         original_format_help = parser.format_help

         def custom_help():
             """ Customized help string, calls the adjusted format_usage. """
             helpmsg = original_format_help()
             helplines = helpmsg.splitlines()
             helplines[0] = parser.format_usage().rstrip()
             return os.linesep.join(helplines) + os.linesep

         parser.format_help = custom_help

     # Parse arguments
     parser = argparse.ArgumentParser(
         description='Include-what-you-use compilation database driver.',
         epilog='Assumes include-what-you-use is available on the PATH.')
     customize_usage(parser)
     customize_help(parser)

     parser.add_argument('-v', '--verbose', action='store_true',
                         help='Print IWYU commands')
     parser.add_argument('-o', '--output-format', type=str,
                         choices=FORMATTERS.keys(), default=DEFAULT_FORMAT,
                         help='Output format (default: %s)' % DEFAULT_FORMAT)
     parser.add_argument('-p', metavar='<build-path>', required=True,
                         help='Compilation database path', dest='dbpath')
     parser.add_argument('source', nargs='*',
                         help='Zero or more source files to run IWYU on. '
                         'Defaults to all in compilation database.')

     def partition_args(argv):
         """ Split around '--' into driver args and IWYU args. """
         try:
             double_dash = argv.index('--')
             return argv[:double_dash], argv[double_dash+1:]
         except ValueError:
             return argv, []
     argv, iwyu_args = partition_args(sys.argv[1:])
     args = parser.parse_args(argv)

     sys.exit(main(args.dbpath, args.source, args.verbose,
                   FORMATTERS[args.output_format], iwyu_args))


 if __name__ == '__main__':
     _bootstrap()
	#!/usr/bin/env python

	# This file has been imported into the Kudu source tree from
	# the IWYU source tree as of version 0.8
	# https://github.com/include-what-you-use/include-what-you-use/blob/master/iwyu_tool.py
	# and corresponding license has been added:
	# https://github.com/include-what-you-use/include-what-you-use/blob/master/LICENSE.TXT
	#
	# ------------------------------------------------------------------------------
	# NOTE: some local Kudu modifications have been made. Before
	# "upgrading" this to a new version from upstream, check the git log.
	# ------------------------------------------------------------------------------
	#
	# ==============================================================================
	# LLVM Release License
	# ==============================================================================
	# University of Illinois/NCSA
	# Open Source License
	#
	# Copyright (c) 2003-2010 University of Illinois at Urbana-Champaign.
	# All rights reserved.
	#
	# Developed by:
	#
	# LLVM Team
	#
	# University of Illinois at Urbana-Champaign
	#
	# http://llvm.org
	#
	# Permission is hereby granted, free of charge, to any person obtaining a copy of
	# this software and associated documentation files (the "Software"), to deal with
	# the Software without restriction, including without limitation the rights to
	# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
	# of the Software, and to permit persons to whom the Software is furnished to do
	# so, subject to the following conditions:
	#
	# * Redistributions of source code must retain the above copyright notice,
	# this list of conditions and the following disclaimers.
	#
	# * Redistributions in binary form must reproduce the above copyright notice,
	# this list of conditions and the following disclaimers in the
	# documentation and/or other materials provided with the distribution.
	#
	# * Neither the names of the LLVM Team, University of Illinois at
	# Urbana-Champaign, nor the names of its contributors may be used to
	# endorse or promote products derived from this Software without specific
	# prior written permission.
	#
	# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
	# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	# CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
	# SOFTWARE.

	""" Driver to consume a Clang compilation database and invoke IWYU.

	Example usage with CMake:

	# Unix systems
	$ mkdir build && cd build
	$ CC="clang" CXX="clang++" cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ...
	$ iwyu_tool.py -p .

	# Windows systems
	$ mkdir build && cd build
	$ cmake -DCMAKE_CXX_COMPILER="%VCINSTALLDIR%/bin/cl.exe" \
	-DCMAKE_C_COMPILER="%VCINSTALLDIR%/VC/bin/cl.exe" \
	-DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
	-G Ninja ...
	$ python iwyu_tool.py -p .

	See iwyu_tool.py -h for more details on command-line arguments.
	"""

	import argparse
	import glob
	import json
	import multiprocessing
	from multiprocessing.pool import ThreadPool
	import os
	import re
	import subprocess
	import sys
	import unittest
	sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
	from kudu_util import get_thirdparty_dir


	def iwyu_formatter(output):
	""" Process iwyu's output, basically a no-op. """
	print('\n'.join(output))


	CORRECT_RE = re.compile(r'^\((.*?) has correct #includes/fwd-decls\)$')
	SHOULD_ADD_RE = re.compile(r'^(.*?) should add these lines:$')
	SHOULD_REMOVE_RE = re.compile(r'^(.*?) should remove these lines:$')
	FULL_LIST_RE = re.compile(r'The full include-list for (.*?):$')
	END_RE = re.compile(r'^---$')
	LINES_RE = re.compile(r'^- (.*?) // lines ([0-9]+)-[0-9]+$')


	GENERAL, ADD, REMOVE, LIST = range(4)


	def clang_formatter(output):
	""" Process iwyu's output into something clang-like. """
	state = (GENERAL, None)
	for line in output:
	match = CORRECT_RE.match(line)
	if match:
	print('%s:1:1: note: #includes/fwd-decls are correct' % match.groups(1))
	continue
	match = SHOULD_ADD_RE.match(line)
	if match:
	state = (ADD, match.group(1))
	continue
	match = SHOULD_REMOVE_RE.match(line)
	if match:
	state = (REMOVE, match.group(1))
	continue
	match = FULL_LIST_RE.match(line)
	if match:
	state = (LIST, match.group(1))
	elif END_RE.match(line):
	state = (GENERAL, None)
	elif not line.strip():
	continue
	elif state[0] == GENERAL:
	print(line)
	elif state[0] == ADD:
	print('%s:1:1: error: add the following line' % state[1])
	print(line)
	elif state[0] == REMOVE:
	match = LINES_RE.match(line)
	line_no = match.group(2) if match else '1'
	print('%s:%s:1: error: remove the following line' % (state[1], line_no))
	print(match.group(1))


	DEFAULT_FORMAT = 'iwyu'
	FORMATTERS = {
	'iwyu': iwyu_formatter,
	'clang': clang_formatter
	}

	def get_output(cwd, args):
	""" Run the given command and return its output as a string. """
	process = subprocess.Popen(args=args,
	cwd=cwd,
	stdout=subprocess.PIPE,
	stderr=subprocess.STDOUT)
	return process.communicate()[0].decode("utf-8").splitlines()


	def run_iwyu(cwd, compile_command, iwyu_args, verbose):
	""" Rewrite compile_command to an IWYU command, and run it. """
	compiler, _, args = compile_command.partition(' ')
	if compiler.endswith('cl.exe'):
	# If the compiler name is cl.exe, let IWYU be cl-compatible
	clang_args = ['--driver-mode=cl']
	else:
	clang_args = []

	extra_args = []
	for a in iwyu_args:
	extra_args += ['-Xiwyu', a]

	cmd_args = ['include-what-you-use'] + clang_args + extra_args + args.split()

	if verbose:
	print('{0}'.format(cmd_args))

	return get_output(cwd, cmd_args)


	def workaround_parent_dir_relative_includes(cwd, command):
	"""
	Replace any relative include paths in the compilation command
	'command' with the appropriate absolute paths.

	This works around an apparent bug in IWYU in which passing relative
	paths like -I../../src/ result in IWYU not reporting issues that it
	otherwise would report when the corresponding absolute path is
	passed.

	Oddly enough, this is only relevant when using the Ninja generator
	for CMake, which results in relative paths in the -I directives. The
	Makefile generator always produces absolute paths to begin with.
	See https://gitlab.kitware.com/cmake/cmake/issues/17450
	"""
	def subber(m):
	return m.group(1) + os.path.abspath(os.path.join(cwd, m.group(2)))
	return re.sub(r'(-isystem \|-I\s*)([^/\s]\S+)', subber, command)


	class RelativeIncludeTest(unittest.TestCase):
	def test(self):
	f = workaround_parent_dir_relative_includes
	self.assertEquals(f('/foo/bar', 'gcc -isystem relative/dir'),
	'gcc -isystem /foo/bar/relative/dir')
	self.assertEquals(f('/foo/bar', 'gcc -I relative/dir'),
	'gcc -I /foo/bar/relative/dir')
	self.assertEquals(f('/foo/bar', 'gcc -Irelative/dir'),
	'gcc -I/foo/bar/relative/dir')

	self.assertEquals(f('/foo/bar', 'gcc -isystem /abs/dir'),
	'gcc -isystem /abs/dir')
	self.assertEquals(f('/foo/bar', 'gcc -I /abs/dir'),
	'gcc -I /abs/dir')
	self.assertEquals(f('/foo/bar', 'gcc -I/abs/dir'),
	'gcc -I/abs/dir')

	def workaround_add_libcpp(build_dir, command):
	"""
	Modify 'command' to include C++ standard library headers from the libc++
	found in Kudu's thirdparty tree.

	By default, IWYU will use the system's libstdc++ for standard library
	headers. This is problematic as every system has a different version of
	libstdc++, leading to differing recommendations depending on the host system.

	If we standardize on libc++ from Kudu's thirdparty tree, we can ensure the
	same recommendations regardless of system, though those recommendations will
	change when libc++ is upgraded.
	"""
	nostdinc = "-nostdinc++"
	if nostdinc not in command:
	command += " " + nostdinc

	# Check for and add any dynamic (path-based) flags.
	#
	# Some sanitizer builds (like TSAN) already include libc++; if the command
	# already has a flag including libc++, we don't want to add it again.
	path_to_libcpp_prefix = os.path.join(get_thirdparty_dir(), "installed")
	path_to_libcpp_suffix = os.path.join("include", "c++", "v1")
	tp_pattern = os.path.join(path_to_libcpp_prefix, "*", path_to_libcpp_suffix)
	found = False
	for path in glob.glob(tp_pattern):
	search_string = "-isystem " + path
	if search_string in command:
	found = True
	break
	if not found:
	path_to_libcpp = os.path.join(path_to_libcpp_prefix, "uninstrumented",
	path_to_libcpp_suffix)
	command += " -isystem " + os.path.abspath(path_to_libcpp)

	return command

	def main(compilation_db_path, source_files, verbose, formatter, iwyu_args):
	""" Entry point. """
	# Canonicalize compilation database path
	if os.path.isdir(compilation_db_path):
	compilation_db_path = os.path.join(compilation_db_path,
	'compile_commands.json')

	compilation_db_path = os.path.realpath(compilation_db_path)
	if not os.path.isfile(compilation_db_path):
	print('ERROR: No such file or directory: \'%s\'' % compilation_db_path)
	return 1

	# Read compilation db from disk
	with open(compilation_db_path, 'r') as fileobj:
	compilation_db = json.load(fileobj)

	# expand symlinks
	for entry in compilation_db:
	entry['file'] = os.path.realpath(entry['file'])

	# Cross-reference source files with compilation database
	source_files = [os.path.realpath(s) for s in source_files]
	if not source_files:
	# No source files specified, analyze entire compilation database
	entries = compilation_db
	else:
	# Source files specified, analyze the ones appearing in compilation db,
	# warn for the rest.
	entries = []
	for source in source_files:
	matches = [e for e in compilation_db if e['file'] == source]
	if matches:
	entries.extend(matches)
	else:
	print('WARNING: \'%s\' not found in compilation database.' %
	source)

	# Run analysis
	build_dir = os.path.dirname(compilation_db_path)
	def run_iwyu_task(entry):
	cwd, compile_command = entry['directory'], entry['command']
	compile_command = workaround_parent_dir_relative_includes(
	cwd, compile_command)
	compile_command = workaround_add_libcpp(build_dir, compile_command)
	return run_iwyu(cwd, compile_command, iwyu_args, verbose)
	pool = ThreadPool(multiprocessing.cpu_count())
	try:
	for iwyu_output in pool.imap_unordered(run_iwyu_task, entries):
	formatter(iwyu_output)
	except KeyboardInterrupt as ki:
	sys.exit(1)
	except OSError as why:
	print('ERROR: Failed to launch include-what-you-use: %s' % why)
	return 1
	finally:
	pool.terminate()
	pool.join()
	return 0


	def _bootstrap():
	""" Parse arguments and dispatch to main(). """
	# This hackery is necessary to add the forwarded IWYU args to the
	# usage and help strings.
	def customize_usage(parser):
	""" Rewrite the parser's format_usage. """
	original_format_usage = parser.format_usage
	parser.format_usage = lambda: original_format_usage().rstrip() + \
	' -- [<IWYU args>]' + os.linesep

	def customize_help(parser):
	""" Rewrite the parser's format_help. """
	original_format_help = parser.format_help

	def custom_help():
	""" Customized help string, calls the adjusted format_usage. """
	helpmsg = original_format_help()
	helplines = helpmsg.splitlines()
	helplines[0] = parser.format_usage().rstrip()
	return os.linesep.join(helplines) + os.linesep

	parser.format_help = custom_help

	# Parse arguments
	parser = argparse.ArgumentParser(
	description='Include-what-you-use compilation database driver.',
	epilog='Assumes include-what-you-use is available on the PATH.')
	customize_usage(parser)
	customize_help(parser)

	parser.add_argument('-v', '--verbose', action='store_true',
	help='Print IWYU commands')
	parser.add_argument('-o', '--output-format', type=str,
	choices=FORMATTERS.keys(), default=DEFAULT_FORMAT,
	help='Output format (default: %s)' % DEFAULT_FORMAT)
	parser.add_argument('-p', metavar='<build-path>', required=True,
	help='Compilation database path', dest='dbpath')
	parser.add_argument('source', nargs='*',
	help='Zero or more source files to run IWYU on. '
	'Defaults to all in compilation database.')

	def partition_args(argv):
	""" Split around '--' into driver args and IWYU args. """
	try:
	double_dash = argv.index('--')
	return argv[:double_dash], argv[double_dash+1:]
	except ValueError:
	return argv, []
	argv, iwyu_args = partition_args(sys.argv[1:])
	args = parser.parse_args(argv)

	sys.exit(main(args.dbpath, args.source, args.verbose,
	FORMATTERS[args.output_format], iwyu_args))


	if __name__ == '__main__':
	_bootstrap()