waf/waflib/Tools/c_config.py

#!/usr/bin/env python
# encoding: utf-8
# Thomas Nagy, 2005-2016 (ita)

"""
C/C++/D configuration helpers
"""

from __future__ import with_statement

import os, re, shlex
from waflib import Build, Utils, Task, Options, Logs, Errors, Runner
from waflib.TaskGen import after_method, feature
from waflib.Configure import conf

WAF_CONFIG_H   = 'config.h'
"""default name for the config.h file"""

DEFKEYS = 'define_key'
INCKEYS = 'include_key'

cfg_ver = {
	'atleast-version': '>=',
	'exact-version': '==',
	'max-version': '<=',
}

SNIP_FUNCTION = '''
int main(int argc, char **argv) {
	void (*p)();
	(void)argc; (void)argv;
	p=(void(*)())(%s);
	return !p;
}
'''
"""Code template for checking for functions"""

SNIP_TYPE = '''
int main(int argc, char **argv) {
	(void)argc; (void)argv;
	if ((%(type_name)s *) 0) return 0;
	if (sizeof (%(type_name)s)) return 0;
	return 1;
}
'''
"""Code template for checking for types"""

SNIP_EMPTY_PROGRAM = '''
int main(int argc, char **argv) {
	(void)argc; (void)argv;
	return 0;
}
'''

SNIP_FIELD = '''
int main(int argc, char **argv) {
	char *off;
	(void)argc; (void)argv;
	off = (char*) &((%(type_name)s*)0)->%(field_name)s;
	return (size_t) off < sizeof(%(type_name)s);
}
'''

MACRO_TO_DESTOS = {
'__linux__'                                      : 'linux',
'__GNU__'                                        : 'gnu', # hurd
'__FreeBSD__'                                    : 'freebsd',
'__NetBSD__'                                     : 'netbsd',
'__OpenBSD__'                                    : 'openbsd',
'__sun'                                          : 'sunos',
'__hpux'                                         : 'hpux',
'__sgi'                                          : 'irix',
'_AIX'                                           : 'aix',
'__CYGWIN__'                                     : 'cygwin',
'__MSYS__'                                       : 'cygwin',
'_UWIN'                                          : 'uwin',
'_WIN64'                                         : 'win32',
'_WIN32'                                         : 'win32',
# Note about darwin: this is also tested with 'defined __APPLE__ && defined __MACH__' somewhere below in this file.
'__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__'  : 'darwin',
'__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__' : 'darwin', # iphone
'__QNX__'                                        : 'qnx',
'__native_client__'                              : 'nacl' # google native client platform
}

MACRO_TO_DEST_CPU = {
'__x86_64__'  : 'x86_64',
'__amd64__'   : 'x86_64',
'__i386__'    : 'x86',
'__ia64__'    : 'ia',
'__mips__'    : 'mips',
'__sparc__'   : 'sparc',
'__alpha__'   : 'alpha',
'__aarch64__' : 'aarch64',
'__thumb__'   : 'thumb',
'__arm__'     : 'arm',
'__hppa__'    : 'hppa',
'__powerpc__' : 'powerpc',
'__ppc__'     : 'powerpc',
'__convex__'  : 'convex',
'__m68k__'    : 'm68k',
'__s390x__'   : 's390x',
'__s390__'    : 's390',
'__sh__'      : 'sh',
'__xtensa__'  : 'xtensa',
}

@conf
def parse_flags(self, line, uselib_store, env=None, force_static=False, posix=None):
	"""
	Parses flags from the input lines, and adds them to the relevant use variables::

		def configure(conf):
			conf.parse_flags('-O3', 'FOO')
			# conf.env.CXXFLAGS_FOO = ['-O3']
			# conf.env.CFLAGS_FOO = ['-O3']

	:param line: flags
	:type line: string
	:param uselib_store: where to add the flags
	:type uselib_store: string
	:param env: config set or conf.env by default
	:type env: :py:class:`waflib.ConfigSet.ConfigSet`
	"""

	assert(isinstance(line, str))

	env = env or self.env

	# Issue 811 and 1371
	if posix is None:
		posix = True
		if '\\' in line:
			posix = ('\\ ' in line) or ('\\\\' in line)

	lex = shlex.shlex(line, posix=posix)
	lex.whitespace_split = True
	lex.commenters = ''
	lst = list(lex)

	# append_unique is not always possible
	# for example, apple flags may require both -arch i386 and -arch ppc
	uselib = uselib_store
	def app(var, val):
		env.append_value('%s_%s' % (var, uselib), val)
	def appu(var, val):
		env.append_unique('%s_%s' % (var, uselib), val)
	static = False
	while lst:
		x = lst.pop(0)
		st = x[:2]
		ot = x[2:]

		if st == '-I' or st == '/I':
			if not ot:
				ot = lst.pop(0)
			appu('INCLUDES', ot)
		elif st == '-i':
			tmp = [x, lst.pop(0)]
			app('CFLAGS', tmp)
			app('CXXFLAGS', tmp)
		elif st == '-D' or (env.CXX_NAME == 'msvc' and st == '/D'): # not perfect but..
			if not ot:
				ot = lst.pop(0)
			app('DEFINES', ot)
		elif st == '-l':
			if not ot:
				ot = lst.pop(0)
			prefix = 'STLIB' if (force_static or static) else 'LIB'
			app(prefix, ot)
		elif st == '-L':
			if not ot:
				ot = lst.pop(0)
			prefix = 'STLIBPATH' if (force_static or static) else 'LIBPATH'
			appu(prefix, ot)
		elif x.startswith('/LIBPATH:'):
			prefix = 'STLIBPATH' if (force_static or static) else 'LIBPATH'
			appu(prefix, x.replace('/LIBPATH:', ''))
		elif x.startswith('-std='):
			prefix = 'CXXFLAGS' if '++' in x else 'CFLAGS'
			app(prefix, x)
		elif x.startswith('+') or x in ('-pthread', '-fPIC', '-fpic', '-fPIE', '-fpie'):
			app('CFLAGS', x)
			app('CXXFLAGS', x)
			app('LINKFLAGS', x)
		elif x == '-framework':
			appu('FRAMEWORK', lst.pop(0))
		elif x.startswith('-F'):
			appu('FRAMEWORKPATH', x[2:])
		elif x == '-Wl,-rpath' or x == '-Wl,-R':
			app('RPATH', lst.pop(0).lstrip('-Wl,'))
		elif x.startswith('-Wl,-R,'):
			app('RPATH', x[7:])
		elif x.startswith('-Wl,-R'):
			app('RPATH', x[6:])
		elif x.startswith('-Wl,-rpath,'):
			app('RPATH', x[11:])
		elif x == '-Wl,-Bstatic' or x == '-Bstatic':
			static = True
		elif x == '-Wl,-Bdynamic' or x == '-Bdynamic':
			static = False
		elif x.startswith('-Wl') or x in ('-rdynamic', '-pie'):
			app('LINKFLAGS', x)
		elif x.startswith(('-m', '-f', '-dynamic', '-O')):
			app('CFLAGS', x)
			app('CXXFLAGS', x)
		elif x.startswith('-bundle'):
			app('LINKFLAGS', x)
		elif x.startswith(('-undefined', '-Xlinker')):
			arg = lst.pop(0)
			app('LINKFLAGS', [x, arg])
		elif x.startswith(('-arch', '-isysroot')):
			tmp = [x, lst.pop(0)]
			app('CFLAGS', tmp)
			app('CXXFLAGS', tmp)
			app('LINKFLAGS', tmp)
		elif x.endswith(('.a', '.so', '.dylib', '.lib')):
			appu('LINKFLAGS', x) # not cool, #762
		else:
			self.to_log('Unhandled flag %r' % x)

@conf
def validate_cfg(self, kw):
	"""
	Searches for the program *pkg-config* if missing, and validates the
	parameters to pass to :py:func:`waflib.Tools.c_config.exec_cfg`.

	:param path: the **-config program to use** (default is *pkg-config*)
	:type path: list of string
	:param msg: message to display to describe the test executed
	:type msg: string
	:param okmsg: message to display when the test is successful
	:type okmsg: string
	:param errmsg: message to display in case of error
	:type errmsg: string
	"""
	if not 'path' in kw:
		if not self.env.PKGCONFIG:
			self.find_program('pkg-config', var='PKGCONFIG')
		kw['path'] = self.env.PKGCONFIG

	# pkg-config version
	if 'atleast_pkgconfig_version' in kw:
		if not 'msg' in kw:
			kw['msg'] = 'Checking for pkg-config version >= %r' % kw['atleast_pkgconfig_version']
		return

	if not 'okmsg' in kw:
		kw['okmsg'] = 'yes'
	if not 'errmsg' in kw:
		kw['errmsg'] = 'not found'

	if 'modversion' in kw:
		if not 'msg' in kw:
			kw['msg'] = 'Checking for %r version' % kw['modversion']
		if not 'uselib_store' in kw:
			kw['uselib_store'] = kw['modversion']
		if not 'define_name' in kw:
			kw['define_name'] = '%s_VERSION' % Utils.quote_define_name(kw['uselib_store'])
		return

	if not 'package' in kw:
		raise ValueError('a package name is required')

	if not 'uselib_store' in kw:
		kw['uselib_store'] = kw['package'].upper()

	if not 'define_name' in kw:
		kw['define_name'] = self.have_define(kw['uselib_store'])

	if not 'msg' in kw:
		kw['msg'] = 'Checking for %r' % (kw['package'] or kw['path'])

	for x in cfg_ver:
		# Gotcha: only one predicate is allowed at a time
		# TODO remove in waf 2.0
		y = x.replace('-', '_')
		if y in kw:
			package = kw['package']
			if Logs.verbose:
				Logs.warn('Passing %r to conf.check_cfg() is obsolete, pass parameters directly, eg:', y)
				Logs.warn(" conf.check_cfg(package='%s', args=['--libs', '--cflags', '%s >= 1.6'])", package, package)
			if not 'msg' in kw:
				kw['msg'] = 'Checking for %r %s %s' % (package, cfg_ver[x], kw[y])
			break

@conf
def exec_cfg(self, kw):
	"""
	Executes ``pkg-config`` or other ``-config`` applications to colect configuration flags:

	* if atleast_pkgconfig_version is given, check that pkg-config has the version n and return
	* if modversion is given, then return the module version
	* else, execute the *-config* program with the *args* and *variables* given, and set the flags on the *conf.env.FLAGS_name* variable

	:param atleast_pkgconfig_version: minimum pkg-config version to use (disable other tests)
	:type atleast_pkgconfig_version: string
	:param package: package name, for example *gtk+-2.0*
	:type package: string
	:param uselib_store: if the test is successful, define HAVE\_*name*. It is also used to define *conf.env.FLAGS_name* variables.
	:type uselib_store: string
	:param modversion: if provided, return the version of the given module and define *name*\_VERSION
	:type modversion: string
	:param args: arguments to give to *package* when retrieving flags
	:type args: list of string
	:param variables: return the values of particular variables
	:type variables: list of string
	:param define_variable: additional variables to define (also in conf.env.PKG_CONFIG_DEFINES)
	:type define_variable: dict(string: string)
	"""

	path = Utils.to_list(kw['path'])
	env = self.env.env or None
	if kw.get('pkg_config_path'):
		if not env:
			env = dict(self.environ)
		env['PKG_CONFIG_PATH'] = kw['pkg_config_path']

	def define_it():
		define_name = kw['define_name']
		# by default, add HAVE_X to the config.h, else provide DEFINES_X for use=X
		if kw.get('global_define', 1):
			self.define(define_name, 1, False)
		else:
			self.env.append_unique('DEFINES_%s' % kw['uselib_store'], "%s=1" % define_name)

		if kw.get('add_have_to_env', 1):
			self.env[define_name] = 1

	# pkg-config version
	if 'atleast_pkgconfig_version' in kw:
		cmd = path + ['--atleast-pkgconfig-version=%s' % kw['atleast_pkgconfig_version']]
		self.cmd_and_log(cmd, env=env)
		if not 'okmsg' in kw:
			kw['okmsg'] = 'yes'
		return

	for x in cfg_ver:
		# TODO remove in waf 2.0
		y = x.replace('-', '_')
		if y in kw:
			self.cmd_and_log(path + ['--%s=%s' % (x, kw[y]), kw['package']], env=env)
			if not 'okmsg' in kw:
				kw['okmsg'] = 'yes'
			define_it()
			break

	# single version for a module
	if 'modversion' in kw:
		version = self.cmd_and_log(path + ['--modversion', kw['modversion']], env=env).strip()
		self.define(kw['define_name'], version)
		return version

	lst = [] + path

	defi = kw.get('define_variable')
	if not defi:
		defi = self.env.PKG_CONFIG_DEFINES or {}
	for key, val in defi.items():
		lst.append('--define-variable=%s=%s' % (key, val))

	static = kw.get('force_static', False)
	if 'args' in kw:
		args = Utils.to_list(kw['args'])
		if '--static' in args or '--static-libs' in args:
			static = True
		lst += args

	# tools like pkgconf expect the package argument after the -- ones -_-
	lst.extend(Utils.to_list(kw['package']))

	# retrieving variables of a module
	if 'variables' in kw:
		v_env = kw.get('env', self.env)
		vars = Utils.to_list(kw['variables'])
		for v in vars:
			val = self.cmd_and_log(lst + ['--variable=' + v], env=env).strip()
			var = '%s_%s' % (kw['uselib_store'], v)
			v_env[var] = val
		if not 'okmsg' in kw:
			kw['okmsg'] = 'yes'
		return

	# so we assume the command-line will output flags to be parsed afterwards
	ret = self.cmd_and_log(lst, env=env)
	if not 'okmsg' in kw:
		kw['okmsg'] = 'yes'

	define_it()
	self.parse_flags(ret, kw['uselib_store'], kw.get('env', self.env), force_static=static, posix=kw.get('posix'))
	return ret

@conf
def check_cfg(self, *k, **kw):
	"""
	Checks for configuration flags using a **-config**-like program (pkg-config, sdl-config, etc).
	This wraps internal calls to :py:func:`waflib.Tools.c_config.validate_cfg` and :py:func:`waflib.Tools.c_config.exec_cfg`

	A few examples::

		def configure(conf):
			conf.load('compiler_c')
			conf.check_cfg(package='glib-2.0', args='--libs --cflags')
			conf.check_cfg(package='glib-2.0', uselib_store='GLIB', atleast_version='2.10.0',
				args='--cflags --libs')
			conf.check_cfg(package='pango')
			conf.check_cfg(package='pango', uselib_store='MYPANGO', args=['--cflags', '--libs'])
			conf.check_cfg(package='pango',
				args=['pango >= 0.1.0', 'pango < 9.9.9', '--cflags', '--libs'],
				msg="Checking for 'pango 0.1.0'")
			conf.check_cfg(path='sdl-config', args='--cflags --libs', package='', uselib_store='SDL')
			conf.check_cfg(path='mpicc', args='--showme:compile --showme:link',
				package='', uselib_store='OPEN_MPI', mandatory=False)
			# variables
			conf.check_cfg(package='gtk+-2.0', variables=['includedir', 'prefix'], uselib_store='FOO')
			print(conf.env.FOO_includedir)
	"""
	if k:
		lst = k[0].split()
		kw['package'] = lst[0]
		kw['args'] = ' '.join(lst[1:])

	self.validate_cfg(kw)
	if 'msg' in kw:
		self.start_msg(kw['msg'], **kw)
	ret = None
	try:
		ret = self.exec_cfg(kw)
	except self.errors.WafError:
		if 'errmsg' in kw:
			self.end_msg(kw['errmsg'], 'YELLOW', **kw)
		if Logs.verbose > 1:
			raise
		else:
			self.fatal('The configuration failed')
	else:
		if not ret:
			ret = True
		kw['success'] = ret
		if 'okmsg' in kw:
			self.end_msg(self.ret_msg(kw['okmsg'], kw), **kw)

	return ret

def build_fun(bld):
	"""
	Build function that is used for running configuration tests with ``conf.check()``
	"""
	if bld.kw['compile_filename']:
		node = bld.srcnode.make_node(bld.kw['compile_filename'])
		node.write(bld.kw['code'])

	o = bld(features=bld.kw['features'], source=bld.kw['compile_filename'], target='testprog')

	for k, v in bld.kw.items():
		setattr(o, k, v)

	if not bld.kw.get('quiet'):
		bld.conf.to_log("==>\n%s\n<==" % bld.kw['code'])

@conf
def validate_c(self, kw):
	"""
	Pre-checks the parameters that will be given to :py:func:`waflib.Configure.run_build`

	:param compiler: c or cxx (tries to guess what is best)
	:type compiler: string
	:param type: cprogram, cshlib, cstlib - not required if *features are given directly*
	:type type: binary to create
	:param feature: desired features for the task generator that will execute the test, for example ``cxx cxxstlib``
	:type feature: list of string
	:param fragment: provide a piece of code for the test (default is to let the system create one)
	:type fragment: string
	:param uselib_store: define variables after the test is executed (IMPORTANT!)
	:type uselib_store: string
	:param use: parameters to use for building (just like the normal *use* keyword)
	:type use: list of string
	:param define_name: define to set when the check is over
	:type define_name: string
	:param execute: execute the resulting binary
	:type execute: bool
	:param define_ret: if execute is set to True, use the execution output in both the define and the return value
	:type define_ret: bool
	:param header_name: check for a particular header
	:type header_name: string
	:param auto_add_header_name: if header_name was set, add the headers in env.INCKEYS so the next tests will include these headers
	:type auto_add_header_name: bool
	"""

	if not 'build_fun' in kw:
		kw['build_fun'] = build_fun

	if not 'env' in kw:
		kw['env'] = self.env.derive()
	env = kw['env']

	if not 'compiler' in kw and not 'features' in kw:
		kw['compiler'] = 'c'
		if env.CXX_NAME and Task.classes.get('cxx'):
			kw['compiler'] = 'cxx'
			if not self.env.CXX:
				self.fatal('a c++ compiler is required')
		else:
			if not self.env.CC:
				self.fatal('a c compiler is required')

	if not 'compile_mode' in kw:
		kw['compile_mode'] = 'c'
		if 'cxx' in Utils.to_list(kw.get('features',[])) or kw.get('compiler', '') == 'cxx':
			kw['compile_mode'] = 'cxx'

	if not 'type' in kw:
		kw['type'] = 'cprogram'

	if not 'features' in kw:
		if not 'header_name' in kw or kw.get('link_header_test', True):
			kw['features'] = [kw['compile_mode'], kw['type']] # "c ccprogram"
		else:
			kw['features'] = [kw['compile_mode']]
	else:
		kw['features'] = Utils.to_list(kw['features'])

	if not 'compile_filename' in kw:
		kw['compile_filename'] = 'test.c' + ((kw['compile_mode'] == 'cxx') and 'pp' or '')

	def to_header(dct):
		if 'header_name' in dct:
			dct = Utils.to_list(dct['header_name'])
			return ''.join(['#include <%s>\n' % x for x in dct])
		return ''

	#OSX
	if 'framework_name' in kw:
		fwkname = kw['framework_name']
		if not 'uselib_store' in kw:
			kw['uselib_store'] = fwkname.upper()
		if not kw.get('no_header', False):
			if not 'header_name' in kw:
				kw['header_name'] = []
			fwk = '%s/%s.h' % (fwkname, fwkname)
			if kw.get('remove_dot_h'):
				fwk = fwk[:-2]
			kw['header_name'] = Utils.to_list(kw['header_name']) + [fwk]

		kw['msg'] = 'Checking for framework %s' % fwkname
		kw['framework'] = fwkname
		#kw['frameworkpath'] = set it yourself

	if 'function_name' in kw:
		fu = kw['function_name']
		if not 'msg' in kw:
			kw['msg'] = 'Checking for function %s' % fu
		kw['code'] = to_header(kw) + SNIP_FUNCTION % fu
		if not 'uselib_store' in kw:
			kw['uselib_store'] = fu.upper()
		if not 'define_name' in kw:
			kw['define_name'] = self.have_define(fu)

	elif 'type_name' in kw:
		tu = kw['type_name']
		if not 'header_name' in kw:
			kw['header_name'] = 'stdint.h'
		if 'field_name' in kw:
			field = kw['field_name']
			kw['code'] = to_header(kw) + SNIP_FIELD % {'type_name' : tu, 'field_name' : field}
			if not 'msg' in kw:
				kw['msg'] = 'Checking for field %s in %s' % (field, tu)
			if not 'define_name' in kw:
				kw['define_name'] = self.have_define((tu + '_' + field).upper())
		else:
			kw['code'] = to_header(kw) + SNIP_TYPE % {'type_name' : tu}
			if not 'msg' in kw:
				kw['msg'] = 'Checking for type %s' % tu
			if not 'define_name' in kw:
				kw['define_name'] = self.have_define(tu.upper())

	elif 'header_name' in kw:
		if not 'msg' in kw:
			kw['msg'] = 'Checking for header %s' % kw['header_name']

		l = Utils.to_list(kw['header_name'])
		assert len(l), 'list of headers in header_name is empty'

		kw['code'] = to_header(kw) + SNIP_EMPTY_PROGRAM
		if not 'uselib_store' in kw:
			kw['uselib_store'] = l[0].upper()
		if not 'define_name' in kw:
			kw['define_name'] = self.have_define(l[0])

	if 'lib' in kw:
		if not 'msg' in kw:
			kw['msg'] = 'Checking for library %s' % kw['lib']
		if not 'uselib_store' in kw:
			kw['uselib_store'] = kw['lib'].upper()

	if 'stlib' in kw:
		if not 'msg' in kw:
			kw['msg'] = 'Checking for static library %s' % kw['stlib']
		if not 'uselib_store' in kw:
			kw['uselib_store'] = kw['stlib'].upper()

	if 'fragment' in kw:
		# an additional code fragment may be provided to replace the predefined code
		# in custom headers
		kw['code'] = kw['fragment']
		if not 'msg' in kw:
			kw['msg'] = 'Checking for code snippet'
		if not 'errmsg' in kw:
			kw['errmsg'] = 'no'

	for (flagsname,flagstype) in (('cxxflags','compiler'), ('cflags','compiler'), ('linkflags','linker')):
		if flagsname in kw:
			if not 'msg' in kw:
				kw['msg'] = 'Checking for %s flags %s' % (flagstype, kw[flagsname])
			if not 'errmsg' in kw:
				kw['errmsg'] = 'no'

	if not 'execute' in kw:
		kw['execute'] = False
	if kw['execute']:
		kw['features'].append('test_exec')
		kw['chmod'] = Utils.O755

	if not 'errmsg' in kw:
		kw['errmsg'] = 'not found'

	if not 'okmsg' in kw:
		kw['okmsg'] = 'yes'

	if not 'code' in kw:
		kw['code'] = SNIP_EMPTY_PROGRAM

	# if there are headers to append automatically to the next tests
	if self.env[INCKEYS]:
		kw['code'] = '\n'.join(['#include <%s>' % x for x in self.env[INCKEYS]]) + '\n' + kw['code']

	# in case defines lead to very long command-lines
	if kw.get('merge_config_header', False) or env.merge_config_header:
		kw['code'] = '%s\n\n%s' % (self.get_config_header(), kw['code'])
		env.DEFINES = [] # modify the copy

	if not kw.get('success'): kw['success'] = None

	if 'define_name' in kw:
		self.undefine(kw['define_name'])
	if not 'msg' in kw:
		self.fatal('missing "msg" in conf.check(...)')

@conf
def post_check(self, *k, **kw):
	"""
	Sets the variables after a test executed in
	:py:func:`waflib.Tools.c_config.check` was run successfully
	"""
	is_success = 0
	if kw['execute']:
		if kw['success'] is not None:
			if kw.get('define_ret', False):
				is_success = kw['success']
			else:
				is_success = (kw['success'] == 0)
	else:
		is_success = (kw['success'] == 0)

	if kw.get('define_name'):
		# TODO this is still way too complicated
		comment = kw.get('comment', '')
		define_name = kw['define_name']
		if kw['execute'] and kw.get('define_ret') and isinstance(is_success, str):
			if kw.get('global_define', 1):
				self.define(define_name, is_success, quote=kw.get('quote', 1), comment=comment)
			else:
				if kw.get('quote', 1):
					succ = '"%s"' % is_success
				else:
					succ = int(is_success)
				val = '%s=%s' % (define_name, succ)
				var = 'DEFINES_%s' % kw['uselib_store']
				self.env.append_value(var, val)
		else:
			if kw.get('global_define', 1):
				self.define_cond(define_name, is_success, comment=comment)
			else:
				var = 'DEFINES_%s' % kw['uselib_store']
				self.env.append_value(var, '%s=%s' % (define_name, int(is_success)))

		# define conf.env.HAVE_X to 1
		if kw.get('add_have_to_env', 1):
			if kw.get('uselib_store'):
				self.env[self.have_define(kw['uselib_store'])] = 1
			elif kw['execute'] and kw.get('define_ret'):
				self.env[define_name] = is_success
			else:
				self.env[define_name] = int(is_success)

	if 'header_name' in kw:
		if kw.get('auto_add_header_name', False):
			self.env.append_value(INCKEYS, Utils.to_list(kw['header_name']))

	if is_success and 'uselib_store' in kw:
		from waflib.Tools import ccroot
		# See get_uselib_vars in ccroot.py
		_vars = set()
		for x in kw['features']:
			if x in ccroot.USELIB_VARS:
				_vars |= ccroot.USELIB_VARS[x]

		for k in _vars:
			x = k.lower()
			if x in kw:
				self.env.append_value(k + '_' + kw['uselib_store'], kw[x])
	return is_success

@conf
def check(self, *k, **kw):
	"""
	Performs a configuration test by calling :py:func:`waflib.Configure.run_build`.
	For the complete list of parameters, see :py:func:`waflib.Tools.c_config.validate_c`.
	To force a specific compiler, pass ``compiler='c'`` or ``compiler='cxx'`` to the list of arguments

	Besides build targets, complete builds can be given through a build function. All files will
	be written to a temporary directory::

		def build(bld):
			lib_node = bld.srcnode.make_node('libdir/liblc1.c')
			lib_node.parent.mkdir()
			lib_node.write('#include <stdio.h>\\nint lib_func(void) { FILE *f = fopen("foo", "r");}\\n', 'w')
			bld(features='c cshlib', source=[lib_node], linkflags=conf.env.EXTRA_LDFLAGS, target='liblc')
		conf.check(build_fun=build, msg=msg)
	"""
	self.validate_c(kw)
	self.start_msg(kw['msg'], **kw)
	ret = None
	try:
		ret = self.run_build(*k, **kw)
	except self.errors.ConfigurationError:
		self.end_msg(kw['errmsg'], 'YELLOW', **kw)
		if Logs.verbose > 1:
			raise
		else:
			self.fatal('The configuration failed')
	else:
		kw['success'] = ret

	ret = self.post_check(*k, **kw)
	if not ret:
		self.end_msg(kw['errmsg'], 'YELLOW', **kw)
		self.fatal('The configuration failed %r' % ret)
	else:
		self.end_msg(self.ret_msg(kw['okmsg'], kw), **kw)
	return ret

class test_exec(Task.Task):
	"""
	A task that runs programs after they are built. See :py:func:`waflib.Tools.c_config.test_exec_fun`.
	"""
	color = 'PINK'
	def run(self):
		if getattr(self.generator, 'rpath', None):
			if getattr(self.generator, 'define_ret', False):
				self.generator.bld.retval = self.generator.bld.cmd_and_log([self.inputs[0].abspath()])
			else:
				self.generator.bld.retval = self.generator.bld.exec_command([self.inputs[0].abspath()])
		else:
			env = self.env.env or {}
			env.update(dict(os.environ))
			for var in ('LD_LIBRARY_PATH', 'DYLD_LIBRARY_PATH', 'PATH'):
				env[var] = self.inputs[0].parent.abspath() + os.path.pathsep + env.get(var, '')
			if getattr(self.generator, 'define_ret', False):
				self.generator.bld.retval = self.generator.bld.cmd_and_log([self.inputs[0].abspath()], env=env)
			else:
				self.generator.bld.retval = self.generator.bld.exec_command([self.inputs[0].abspath()], env=env)

@feature('test_exec')
@after_method('apply_link')
def test_exec_fun(self):
	"""
	The feature **test_exec** is used to create a task that will to execute the binary
	created (link task output) during the build. The exit status will be set
	on the build context, so only one program may have the feature *test_exec*.
	This is used by configuration tests::

		def configure(conf):
			conf.check(execute=True)
	"""
	self.create_task('test_exec', self.link_task.outputs[0])

@conf
def check_cxx(self, *k, **kw):
	"""
	Runs a test with a task generator of the form::

		conf.check(features='cxx cxxprogram', ...)
	"""
	kw['compiler'] = 'cxx'
	return self.check(*k, **kw)

@conf
def check_cc(self, *k, **kw):
	"""
	Runs a test with a task generator of the form::

		conf.check(features='c cprogram', ...)
	"""
	kw['compiler'] = 'c'
	return self.check(*k, **kw)

@conf
def set_define_comment(self, key, comment):
	"""
	Sets a comment that will appear in the configuration header

	:type key: string
	:type comment: string
	"""
	coms = self.env.DEFINE_COMMENTS
	if not coms:
		coms = self.env.DEFINE_COMMENTS = {}
	coms[key] = comment or ''

@conf
def get_define_comment(self, key):
	"""
	Returns the comment associated to a define

	:type key: string
	"""
	coms = self.env.DEFINE_COMMENTS or {}
	return coms.get(key, '')

@conf
def define(self, key, val, quote=True, comment=''):
	"""
	Stores a single define and its state into ``conf.env.DEFINES``. The value is cast to an integer (0/1).

	:param key: define name
	:type key: string
	:param val: value
	:type val: int or string
	:param quote: enclose strings in quotes (yes by default)
	:type quote: bool
	"""
	assert isinstance(key, str)
	if not key:
		return
	if val is True:
		val = 1
	elif val in (False, None):
		val = 0

	if isinstance(val, int) or isinstance(val, float):
		s = '%s=%s'
	else:
		s = quote and '%s="%s"' or '%s=%s'
	app = s % (key, str(val))

	ban = key + '='
	lst = self.env.DEFINES
	for x in lst:
		if x.startswith(ban):
			lst[lst.index(x)] = app
			break
	else:
		self.env.append_value('DEFINES', app)

	self.env.append_unique(DEFKEYS, key)
	self.set_define_comment(key, comment)

@conf
def undefine(self, key, comment=''):
	"""
	Removes a global define from ``conf.env.DEFINES``

	:param key: define name
	:type key: string
	"""
	assert isinstance(key, str)
	if not key:
		return
	ban = key + '='
	lst = [x for x in self.env.DEFINES if not x.startswith(ban)]
	self.env.DEFINES = lst
	self.env.append_unique(DEFKEYS, key)
	self.set_define_comment(key, comment)

@conf
def define_cond(self, key, val, comment=''):
	"""
	Conditionally defines a name::

		def configure(conf):
			conf.define_cond('A', True)
			# equivalent to:
			# if val: conf.define('A', 1)
			# else: conf.undefine('A')

	:param key: define name
	:type key: string
	:param val: value
	:type val: int or string
	"""
	assert isinstance(key, str)
	if not key:
		return
	if val:
		self.define(key, 1, comment=comment)
	else:
		self.undefine(key, comment=comment)

@conf
def is_defined(self, key):
	"""
	Indicates whether a particular define is globally set in ``conf.env.DEFINES``.

	:param key: define name
	:type key: string
	:return: True if the define is set
	:rtype: bool
	"""
	assert key and isinstance(key, str)

	ban = key + '='
	for x in self.env.DEFINES:
		if x.startswith(ban):
			return True
	return False

@conf
def get_define(self, key):
	"""
	Returns the value of an existing define, or None if not found

	:param key: define name
	:type key: string
	:rtype: string
	"""
	assert key and isinstance(key, str)

	ban = key + '='
	for x in self.env.DEFINES:
		if x.startswith(ban):
			return x[len(ban):]
	return None

@conf
def have_define(self, key):
	"""
	Returns a variable suitable for command-line or header use by removing invalid characters
	and prefixing it with ``HAVE_``

	:param key: define name
	:type key: string
	:return: the input key prefixed by *HAVE_* and substitute any invalid characters.
	:rtype: string
	"""
	return (self.env.HAVE_PAT or 'HAVE_%s') % Utils.quote_define_name(key)

@conf
def write_config_header(self, configfile='', guard='', top=False, defines=True, headers=False, remove=True, define_prefix=''):
	"""
	Writes a configuration header containing defines and includes::

		def configure(cnf):
			cnf.define('A', 1)
			cnf.write_config_header('config.h')

	This function only adds include guards (if necessary), consult
	:py:func:`waflib.Tools.c_config.get_config_header` for details on the body.

	:param configfile: path to the file to create (relative or absolute)
	:type configfile: string
	:param guard: include guard name to add, by default it is computed from the file name
	:type guard: string
	:param top: write the configuration header from the build directory (default is from the current path)
	:type top: bool
	:param defines: add the defines (yes by default)
	:type defines: bool
	:param headers: add #include in the file
	:type headers: bool
	:param remove: remove the defines after they are added (yes by default, works like in autoconf)
	:type remove: bool
	:type define_prefix: string
	:param define_prefix: prefix all the defines in the file with a particular prefix
	"""
	if not configfile:
		configfile = WAF_CONFIG_H
	waf_guard = guard or 'W_%s_WAF' % Utils.quote_define_name(configfile)

	node = top and self.bldnode or self.path.get_bld()
	node = node.make_node(configfile)
	node.parent.mkdir()

	lst = ['/* WARNING! All changes made to this file will be lost! */\n']
	lst.append('#ifndef %s\n#define %s\n' % (waf_guard, waf_guard))
	lst.append(self.get_config_header(defines, headers, define_prefix=define_prefix))
	lst.append('\n#endif /* %s */\n' % waf_guard)

	node.write('\n'.join(lst))

	# config files must not be removed on "waf clean"
	self.env.append_unique(Build.CFG_FILES, [node.abspath()])

	if remove:
		for key in self.env[DEFKEYS]:
			self.undefine(key)
		self.env[DEFKEYS] = []

@conf
def get_config_header(self, defines=True, headers=False, define_prefix=''):
	"""
	Creates the contents of a ``config.h`` file from the defines and includes
	set in conf.env.define_key / conf.env.include_key. No include guards are added.

	A prelude will be added from the variable env.WAF_CONFIG_H_PRELUDE if provided. This
	can be used to insert complex macros or include guards::

		def configure(conf):
			conf.env.WAF_CONFIG_H_PRELUDE = '#include <unistd.h>\\n'
			conf.write_config_header('config.h')

	:param defines: write the defines values
	:type defines: bool
	:param headers: write include entries for each element in self.env.INCKEYS
	:type headers: bool
	:type define_prefix: string
	:param define_prefix: prefix all the defines with a particular prefix
	:return: the contents of a ``config.h`` file
	:rtype: string
	"""
	lst = []

	if self.env.WAF_CONFIG_H_PRELUDE:
		lst.append(self.env.WAF_CONFIG_H_PRELUDE)

	if headers:
		for x in self.env[INCKEYS]:
			lst.append('#include <%s>' % x)

	if defines:
		tbl = {}
		for k in self.env.DEFINES:
			a, _, b = k.partition('=')
			tbl[a] = b

		for k in self.env[DEFKEYS]:
			caption = self.get_define_comment(k)
			if caption:
				caption = ' /* %s */' % caption
			try:
				txt = '#define %s%s %s%s' % (define_prefix, k, tbl[k], caption)
			except KeyError:
				txt = '/* #undef %s%s */%s' % (define_prefix, k, caption)
			lst.append(txt)
	return "\n".join(lst)

@conf
def cc_add_flags(conf):
	"""
	Adds CFLAGS / CPPFLAGS from os.environ to conf.env
	"""
	conf.add_os_flags('CPPFLAGS', dup=False)
	conf.add_os_flags('CFLAGS', dup=False)

@conf
def cxx_add_flags(conf):
	"""
	Adds CXXFLAGS / CPPFLAGS from os.environ to conf.env
	"""
	conf.add_os_flags('CPPFLAGS', dup=False)
	conf.add_os_flags('CXXFLAGS', dup=False)

@conf
def link_add_flags(conf):
	"""
	Adds LINKFLAGS / LDFLAGS from os.environ to conf.env
	"""
	conf.add_os_flags('LINKFLAGS', dup=False)
	conf.add_os_flags('LDFLAGS', dup=False)

@conf
def cc_load_tools(conf):
	"""
	Loads the Waf c extensions
	"""
	if not conf.env.DEST_OS:
		conf.env.DEST_OS = Utils.unversioned_sys_platform()
	conf.load('c')

@conf
def cxx_load_tools(conf):
	"""
	Loads the Waf c++ extensions
	"""
	if not conf.env.DEST_OS:
		conf.env.DEST_OS = Utils.unversioned_sys_platform()
	conf.load('cxx')

@conf
def get_cc_version(conf, cc, gcc=False, icc=False, clang=False):
	"""
	Runs the preprocessor to determine the gcc/icc/clang version

	The variables CC_VERSION, DEST_OS, DEST_BINFMT and DEST_CPU will be set in *conf.env*

	:raise: :py:class:`waflib.Errors.ConfigurationError`
	"""
	cmd = cc + ['-dM', '-E', '-']
	env = conf.env.env or None
	try:
		out, err = conf.cmd_and_log(cmd, output=0, input='\n'.encode(), env=env)
	except Exception:
		conf.fatal('Could not determine the compiler version %r' % cmd)

	if gcc:
		if out.find('__INTEL_COMPILER') >= 0:
			conf.fatal('The intel compiler pretends to be gcc')
		if out.find('__GNUC__') < 0 and out.find('__clang__') < 0:
			conf.fatal('Could not determine the compiler type')

	if icc and out.find('__INTEL_COMPILER') < 0:
		conf.fatal('Not icc/icpc')

	if clang and out.find('__clang__') < 0:
		conf.fatal('Not clang/clang++')
	if not clang and out.find('__clang__') >= 0:
		conf.fatal('Could not find gcc/g++ (only Clang), if renamed try eg: CC=gcc48 CXX=g++48 waf configure')

	k = {}
	if icc or gcc or clang:
		out = out.splitlines()
		for line in out:
			lst = shlex.split(line)
			if len(lst)>2:
				key = lst[1]
				val = lst[2]
				k[key] = val

		def isD(var):
			return var in k

		# Some documentation is available at http://predef.sourceforge.net
		# The names given to DEST_OS must match what Utils.unversioned_sys_platform() returns.
		if not conf.env.DEST_OS:
			conf.env.DEST_OS = ''
		for i in MACRO_TO_DESTOS:
			if isD(i):
				conf.env.DEST_OS = MACRO_TO_DESTOS[i]
				break
		else:
			if isD('__APPLE__') and isD('__MACH__'):
				conf.env.DEST_OS = 'darwin'
			elif isD('__unix__'): # unix must be tested last as it's a generic fallback
				conf.env.DEST_OS = 'generic'

		if isD('__ELF__'):
			conf.env.DEST_BINFMT = 'elf'
		elif isD('__WINNT__') or isD('__CYGWIN__') or isD('_WIN32'):
			conf.env.DEST_BINFMT = 'pe'
			if not conf.env.IMPLIBDIR:
				conf.env.IMPLIBDIR = conf.env.LIBDIR # for .lib or .dll.a files
			conf.env.LIBDIR = conf.env.BINDIR
		elif isD('__APPLE__'):
			conf.env.DEST_BINFMT = 'mac-o'

		if not conf.env.DEST_BINFMT:
			# Infer the binary format from the os name.
			conf.env.DEST_BINFMT = Utils.destos_to_binfmt(conf.env.DEST_OS)

		for i in MACRO_TO_DEST_CPU:
			if isD(i):
				conf.env.DEST_CPU = MACRO_TO_DEST_CPU[i]
				break

		Logs.debug('ccroot: dest platform: ' + ' '.join([conf.env[x] or '?' for x in ('DEST_OS', 'DEST_BINFMT', 'DEST_CPU')]))
		if icc:
			ver = k['__INTEL_COMPILER']
			conf.env.CC_VERSION = (ver[:-2], ver[-2], ver[-1])
		else:
			if isD('__clang__') and isD('__clang_major__'):
				conf.env.CC_VERSION = (k['__clang_major__'], k['__clang_minor__'], k['__clang_patchlevel__'])
			else:
				# older clang versions and gcc
				conf.env.CC_VERSION = (k['__GNUC__'], k['__GNUC_MINOR__'], k.get('__GNUC_PATCHLEVEL__', '0'))
	return k

@conf
def get_xlc_version(conf, cc):
	"""
	Returns the Aix compiler version

	:raise: :py:class:`waflib.Errors.ConfigurationError`
	"""
	cmd = cc + ['-qversion']
	try:
		out, err = conf.cmd_and_log(cmd, output=0)
	except Errors.WafError:
		conf.fatal('Could not find xlc %r' % cmd)

	# the intention is to catch the 8.0 in "IBM XL C/C++ Enterprise Edition V8.0 for AIX..."
	for v in (r"IBM XL C/C\+\+.* V(?P<major>\d*)\.(?P<minor>\d*)",):
		version_re = re.compile(v, re.I).search
		match = version_re(out or err)
		if match:
			k = match.groupdict()
			conf.env.CC_VERSION = (k['major'], k['minor'])
			break
	else:
		conf.fatal('Could not determine the XLC version.')

@conf
def get_suncc_version(conf, cc):
	"""
	Returns the Sun compiler version

	:raise: :py:class:`waflib.Errors.ConfigurationError`
	"""
	cmd = cc + ['-V']
	try:
		out, err = conf.cmd_and_log(cmd, output=0)
	except Errors.WafError as e:
		# Older versions of the compiler exit with non-zero status when reporting their version
		if not (hasattr(e, 'returncode') and hasattr(e, 'stdout') and hasattr(e, 'stderr')):
			conf.fatal('Could not find suncc %r' % cmd)
		out = e.stdout
		err = e.stderr

	version = (out or err)
	version = version.splitlines()[0]

	# cc: Sun C 5.10 SunOS_i386 2009/06/03
	# cc: Studio 12.5 Sun C++ 5.14 SunOS_sparc Beta 2015/11/17
	# cc: WorkShop Compilers 5.0 98/12/15 C 5.0
	version_re = re.compile(r'cc: (studio.*?|\s+)?(sun\s+(c\+\+|c)|(WorkShop\s+Compilers))?\s+(?P<major>\d*)\.(?P<minor>\d*)', re.I).search
	match = version_re(version)
	if match:
		k = match.groupdict()
		conf.env.CC_VERSION = (k['major'], k['minor'])
	else:
		conf.fatal('Could not determine the suncc version.')

# ============ the --as-needed flag should added during the configuration, not at runtime =========

@conf
def add_as_needed(self):
	"""
	Adds ``--as-needed`` to the *LINKFLAGS*
	On some platforms, it is a default flag.  In some cases (e.g., in NS-3) it is necessary to explicitly disable this feature with `-Wl,--no-as-needed` flag.
	"""
	if self.env.DEST_BINFMT == 'elf' and 'gcc' in (self.env.CXX_NAME, self.env.CC_NAME):
		self.env.append_unique('LINKFLAGS', '-Wl,--as-needed')

# ============ parallel configuration

class cfgtask(Task.TaskBase):
	"""
	A task that executes build configuration tests (calls conf.check)

	Make sure to use locks if concurrent access to the same conf.env data is necessary.
	"""
	def __init__(self, *k, **kw):
		Task.TaskBase.__init__(self, *k, **kw)
		self.run_after = set()

	def display(self):
		return ''

	def runnable_status(self):
		for x in self.run_after:
			if not x.hasrun:
				return Task.ASK_LATER
		return Task.RUN_ME

	def uid(self):
		return Utils.SIG_NIL

	def run(self):
		conf = self.conf
		bld = Build.BuildContext(top_dir=conf.srcnode.abspath(), out_dir=conf.bldnode.abspath())
		bld.env = conf.env
		bld.init_dirs()
		bld.in_msg = 1 # suppress top-level start_msg
		bld.logger = self.logger
		bld.multicheck_task = self
		args = self.args
		try:
			if 'func' in args:
				bld.test(build_fun=args['func'],
					msg=args.get('msg', ''),
					okmsg=args.get('okmsg', ''),
					errmsg=args.get('errmsg', ''),
					)
			else:
				args['multicheck_mandatory'] = args.get('mandatory', True)
				args['mandatory'] = True
				try:
					bld.check(**args)
				finally:
					args['mandatory'] = args['multicheck_mandatory']
		except Exception:
			return 1

	def process(self):
		Task.TaskBase.process(self)
		if 'msg' in self.args:
			with self.generator.bld.multicheck_lock:
				self.conf.start_msg(self.args['msg'])
				if self.hasrun == Task.NOT_RUN:
					self.conf.end_msg('test cancelled', 'YELLOW')
				elif self.hasrun != Task.SUCCESS:
					self.conf.end_msg(self.args.get('errmsg', 'no'), 'YELLOW')
				else:
					self.conf.end_msg(self.args.get('okmsg', 'yes'), 'GREEN')

@conf
def multicheck(self, *k, **kw):
	"""
	Runs configuration tests in parallel; results are printed sequentially at the end of the build
	but each test must provide its own msg value to display a line::

		def test_build(ctx):
			ctx.in_msg = True # suppress console outputs
			ctx.check_large_file(mandatory=False)

		conf.multicheck(
			{'header_name':'stdio.h', 'msg':'... stdio', 'uselib_store':'STDIO', 'global_define':False},
			{'header_name':'xyztabcd.h', 'msg':'... optional xyztabcd.h', 'mandatory': False},
			{'header_name':'stdlib.h', 'msg':'... stdlib', 'okmsg': 'aye', 'errmsg': 'nope'},
			{'func': test_build, 'msg':'... testing an arbitrary build function', 'okmsg':'ok'},
			msg       = 'Checking for headers in parallel',
			mandatory = True, # mandatory tests raise an error at the end
			run_all_tests = True, # try running all tests
		)

	The configuration tests may modify the values in conf.env in any order, and the define
	values can affect configuration tests being executed. It is hence recommended
	to provide `uselib_store` values with `global_define=False` to prevent such issues.
	"""
	self.start_msg(kw.get('msg', 'Executing %d configuration tests' % len(k)), **kw)

	# Force a copy so that threads append to the same list at least
	# no order is guaranteed, but the values should not disappear at least
	for var in ('DEFINES', DEFKEYS):
		self.env.append_value(var, [])
	self.env.DEFINE_COMMENTS = self.env.DEFINE_COMMENTS or {}

	# define a task object that will execute our tests
	class par(object):
		def __init__(self):
			self.keep = False
			self.task_sigs = {}
			self.progress_bar = 0
		def total(self):
			return len(tasks)
		def to_log(self, *k, **kw):
			return

	bld = par()
	bld.keep = kw.get('run_all_tests', True)
	tasks = []

	id_to_task = {}
	for dct in k:
		x = Task.classes['cfgtask'](bld=bld)
		tasks.append(x)
		x.args = dct
		x.bld = bld
		x.conf = self
		x.args = dct

		# bind a logger that will keep the info in memory
		x.logger = Logs.make_mem_logger(str(id(x)), self.logger)

		if 'id' in dct:
			id_to_task[dct['id']] = x

	# second pass to set dependencies with after_test/before_test
	for x in tasks:
		for key in Utils.to_list(x.args.get('before_tests', [])):
			tsk = id_to_task[key]
			if not tsk:
				raise ValueError('No test named %r' % key)
			tsk.run_after.add(x)
		for key in Utils.to_list(x.args.get('after_tests', [])):
			tsk = id_to_task[key]
			if not tsk:
				raise ValueError('No test named %r' % key)
			x.run_after.add(tsk)

	def it():
		yield tasks
		while 1:
			yield []
	bld.producer = p = Runner.Parallel(bld, Options.options.jobs)
	bld.multicheck_lock = Utils.threading.Lock()
	p.biter = it()

	self.end_msg('started')
	p.start()

	# flush the logs in order into the config.log
	for x in tasks:
		x.logger.memhandler.flush()

	self.start_msg('-> processing test results')
	if p.error:
		for x in p.error:
			if getattr(x, 'err_msg', None):
				self.to_log(x.err_msg)
				self.end_msg('fail', color='RED')
				raise Errors.WafError('There is an error in the library, read config.log for more information')

	failure_count = 0
	for x in tasks:
		if x.hasrun not in (Task.SUCCESS, Task.NOT_RUN):
			failure_count += 1

	if failure_count:
		self.end_msg(kw.get('errmsg', '%s test failed' % failure_count), color='YELLOW', **kw)
	else:
		self.end_msg('all ok', **kw)

	for x in tasks:
		if x.hasrun != Task.SUCCESS:
			if x.args.get('mandatory', True):
				self.fatal(kw.get('fatalmsg') or 'One of the tests has failed, read config.log for more information')

@conf
def check_gcc_o_space(self, mode='c'):
	if int(self.env.CC_VERSION[0]) > 4:
		# this is for old compilers
		return
	self.env.stash()
	if mode == 'c':
		self.env.CCLNK_TGT_F = ['-o', '']
	elif mode == 'cxx':
		self.env.CXXLNK_TGT_F = ['-o', '']
	features = '%s %sshlib' % (mode, mode)
	try:
		self.check(msg='Checking if the -o link must be split from arguments', fragment=SNIP_EMPTY_PROGRAM, features=features)
	except self.errors.ConfigurationError:
		self.env.revert()
	else:
		self.env.commit()