Squashed 'waflib/' changes from 915dcb1..e7a29b6

e7a29b6 Upgrade to waf 2.0.15
8280f9d Add command for running executables from the build directory
8073c1a Make make_simple_dox() safe in case of exception
70d03b8 Avoid use of global counter hacks for configuration display
b7d689a Rewrite test framework
94deadf Automatically add options and move add_flags() to options context
f4259ee Reduce system include path noise
927b608 Automatically display configuration header
c44b8f3 Set line justification from a constant in the wscript
a48e26f Automatically detect if wscript has a test hook
ef66724 Save runtime variables in the environment
63bcbcd Clean up TestContext
b1d9505 Add ExecutionContext for setting runtime environment
387c1df Add show_diff() and test_file_equals() utilities
29d4d29 Fix in-tree library paths
9fde01f Add custom configuration context
6d3612f Add lib_path_name constant

git-subtree-dir: waflib
git-subtree-split: e7a29b6b9b2f842314244c23c14d8f8f560904e1

1 files changed, 737 insertions, 0 deletions

diff --git a/Context.py b/Context.py
new file mode 100644
index 0000000..876ea46
--- /dev/null
+++ b/Context.py
@@ -0,0 +1,737 @@
+#!/usr/bin/env python
+# encoding: utf-8
+# Thomas Nagy, 2010-2018 (ita)
+
+"""
+Classes and functions enabling the command system
+"""
+
+import os, re, imp, sys
+from waflib import Utils, Errors, Logs
+import waflib.Node
+
+# the following 3 constants are updated on each new release (do not touch)
+HEXVERSION=0x2000f00
+"""Constant updated on new releases"""
+
+WAFVERSION="2.0.15"
+"""Constant updated on new releases"""
+
+WAFREVISION="503db290b73ef738a495e0d116d6f8ee0b98dcc2"
+"""Git revision when the waf version is updated"""
+
+ABI = 20
+"""Version of the build data cache file format (used in :py:const:`waflib.Context.DBFILE`)"""
+
+DBFILE = '.wafpickle-%s-%d-%d' % (sys.platform, sys.hexversion, ABI)
+"""Name of the pickle file for storing the build data"""
+
+APPNAME = 'APPNAME'
+"""Default application name (used by ``waf dist``)"""
+
+VERSION = 'VERSION'
+"""Default application version (used by ``waf dist``)"""
+
+TOP  = 'top'
+"""The variable name for the top-level directory in wscript files"""
+
+OUT  = 'out'
+"""The variable name for the output directory in wscript files"""
+
+WSCRIPT_FILE = 'wscript'
+"""Name of the waf script files"""
+
+launch_dir = ''
+"""Directory from which waf has been called"""
+run_dir = ''
+"""Location of the wscript file to use as the entry point"""
+top_dir = ''
+"""Location of the project directory (top), if the project was configured"""
+out_dir = ''
+"""Location of the build directory (out), if the project was configured"""
+waf_dir = ''
+"""Directory containing the waf modules"""
+
+default_encoding = Utils.console_encoding()
+"""Encoding to use when reading outputs from other processes"""
+
+g_module = None
+"""
+Module representing the top-level wscript file (see :py:const:`waflib.Context.run_dir`)
+"""
+
+STDOUT = 1
+STDERR = -1
+BOTH   = 0
+
+classes = []
+"""
+List of :py:class:`waflib.Context.Context` subclasses that can be used as waf commands. The classes
+are added automatically by a metaclass.
+"""
+
+def create_context(cmd_name, *k, **kw):
+	"""
+	Returns a new :py:class:`waflib.Context.Context` instance corresponding to the given command.
+	Used in particular by :py:func:`waflib.Scripting.run_command`
+
+	:param cmd_name: command name
+	:type cmd_name: string
+	:param k: arguments to give to the context class initializer
+	:type k: list
+	:param k: keyword arguments to give to the context class initializer
+	:type k: dict
+	:return: Context object
+	:rtype: :py:class:`waflib.Context.Context`
+	"""
+	for x in classes:
+		if x.cmd == cmd_name:
+			return x(*k, **kw)
+	ctx = Context(*k, **kw)
+	ctx.fun = cmd_name
+	return ctx
+
+class store_context(type):
+	"""
+	Metaclass that registers command classes into the list :py:const:`waflib.Context.classes`
+	Context classes must provide an attribute 'cmd' representing the command name, and a function
+	attribute 'fun' representing the function name that the command uses.
+	"""
+	def __init__(cls, name, bases, dct):
+		super(store_context, cls).__init__(name, bases, dct)
+		name = cls.__name__
+
+		if name in ('ctx', 'Context'):
+			return
+
+		try:
+			cls.cmd
+		except AttributeError:
+			raise Errors.WafError('Missing command for the context class %r (cmd)' % name)
+
+		if not getattr(cls, 'fun', None):
+			cls.fun = cls.cmd
+
+		classes.insert(0, cls)
+
+ctx = store_context('ctx', (object,), {})
+"""Base class for all :py:class:`waflib.Context.Context` classes"""
+
+class Context(ctx):
+	"""
+	Default context for waf commands, and base class for new command contexts.
+
+	Context objects are passed to top-level functions::
+
+		def foo(ctx):
+			print(ctx.__class__.__name__) # waflib.Context.Context
+
+	Subclasses must define the class attributes 'cmd' and 'fun':
+
+	:param cmd: command to execute as in ``waf cmd``
+	:type cmd: string
+	:param fun: function name to execute when the command is called
+	:type fun: string
+
+	.. inheritance-diagram:: waflib.Context.Context waflib.Build.BuildContext waflib.Build.InstallContext waflib.Build.UninstallContext waflib.Build.StepContext waflib.Build.ListContext waflib.Configure.ConfigurationContext waflib.Scripting.Dist waflib.Scripting.DistCheck waflib.Build.CleanContext
+
+	"""
+
+	errors = Errors
+	"""
+	Shortcut to :py:mod:`waflib.Errors` provided for convenience
+	"""
+
+	tools = {}
+	"""
+	A module cache for wscript files; see :py:meth:`Context.Context.load`
+	"""
+
+	def __init__(self, **kw):
+		try:
+			rd = kw['run_dir']
+		except KeyError:
+			rd = run_dir
+
+		# binds the context to the nodes in use to avoid a context singleton
+		self.node_class = type('Nod3', (waflib.Node.Node,), {})
+		self.node_class.__module__ = 'waflib.Node'
+		self.node_class.ctx = self
+
+		self.root = self.node_class('', None)
+		self.cur_script = None
+		self.path = self.root.find_dir(rd)
+
+		self.stack_path = []
+		self.exec_dict = {'ctx':self, 'conf':self, 'bld':self, 'opt':self}
+		self.logger = None
+
+	def finalize(self):
+		"""
+		Called to free resources such as logger files
+		"""
+		try:
+			logger = self.logger
+		except AttributeError:
+			pass
+		else:
+			Logs.free_logger(logger)
+			delattr(self, 'logger')
+
+	def load(self, tool_list, *k, **kw):
+		"""
+		Loads a Waf tool as a module, and try calling the function named :py:const:`waflib.Context.Context.fun`
+		from it.  A ``tooldir`` argument may be provided as a list of module paths.
+
+		:param tool_list: list of Waf tool names to load
+		:type tool_list: list of string or space-separated string
+		"""
+		tools = Utils.to_list(tool_list)
+		path = Utils.to_list(kw.get('tooldir', ''))
+		with_sys_path = kw.get('with_sys_path', True)
+
+		for t in tools:
+			module = load_tool(t, path, with_sys_path=with_sys_path)
+			fun = getattr(module, kw.get('name', self.fun), None)
+			if fun:
+				fun(self)
+
+	def execute(self):
+		"""
+		Here, it calls the function name in the top-level wscript file. Most subclasses
+		redefine this method to provide additional functionality.
+		"""
+		self.recurse([os.path.dirname(g_module.root_path)])
+
+	def pre_recurse(self, node):
+		"""
+		Method executed immediately before a folder is read by :py:meth:`waflib.Context.Context.recurse`.
+		The current script is bound as a Node object on ``self.cur_script``, and the current path
+		is bound to ``self.path``
+
+		:param node: script
+		:type node: :py:class:`waflib.Node.Node`
+		"""
+		self.stack_path.append(self.cur_script)
+
+		self.cur_script = node
+		self.path = node.parent
+
+	def post_recurse(self, node):
+		"""
+		Restores ``self.cur_script`` and ``self.path`` right after :py:meth:`waflib.Context.Context.recurse` terminates.
+
+		:param node: script
+		:type node: :py:class:`waflib.Node.Node`
+		"""
+		self.cur_script = self.stack_path.pop()
+		if self.cur_script:
+			self.path = self.cur_script.parent
+
+	def recurse(self, dirs, name=None, mandatory=True, once=True, encoding=None):
+		"""
+		Runs user-provided functions from the supplied list of directories.
+		The directories can be either absolute, or relative to the directory
+		of the wscript file
+
+		The methods :py:meth:`waflib.Context.Context.pre_recurse` and
+		:py:meth:`waflib.Context.Context.post_recurse` are called immediately before
+		and after a script has been executed.
+
+		:param dirs: List of directories to visit
+		:type dirs: list of string or space-separated string
+		:param name: Name of function to invoke from the wscript
+		:type  name: string
+		:param mandatory: whether sub wscript files are required to exist
+		:type  mandatory: bool
+		:param once: read the script file once for a particular context
+		:type once: bool
+		"""
+		try:
+			cache = self.recurse_cache
+		except AttributeError:
+			cache = self.recurse_cache = {}
+
+		for d in Utils.to_list(dirs):
+
+			if not os.path.isabs(d):
+				# absolute paths only
+				d = os.path.join(self.path.abspath(), d)
+
+			WSCRIPT     = os.path.join(d, WSCRIPT_FILE)
+			WSCRIPT_FUN = WSCRIPT + '_' + (name or self.fun)
+
+			node = self.root.find_node(WSCRIPT_FUN)
+			if node and (not once or node not in cache):
+				cache[node] = True
+				self.pre_recurse(node)
+				try:
+					function_code = node.read('r', encoding)
+					exec(compile(function_code, node.abspath(), 'exec'), self.exec_dict)
+				finally:
+					self.post_recurse(node)
+			elif not node:
+				node = self.root.find_node(WSCRIPT)
+				tup = (node, name or self.fun)
+				if node and (not once or tup not in cache):
+					cache[tup] = True
+					self.pre_recurse(node)
+					try:
+						wscript_module = load_module(node.abspath(), encoding=encoding)
+						user_function = getattr(wscript_module, (name or self.fun), None)
+						if not user_function:
+							if not mandatory:
+								continue
+							raise Errors.WafError('No function %r defined in %s' % (name or self.fun, node.abspath()))
+						user_function(self)
+					finally:
+						self.post_recurse(node)
+				elif not node:
+					if not mandatory:
+						continue
+					try:
+						os.listdir(d)
+					except OSError:
+						raise Errors.WafError('Cannot read the folder %r' % d)
+					raise Errors.WafError('No wscript file in directory %s' % d)
+
+	def log_command(self, cmd, kw):
+		if Logs.verbose:
+			fmt = os.environ.get('WAF_CMD_FORMAT')
+			if fmt == 'string':
+				if not isinstance(cmd, str):
+					cmd = Utils.shell_escape(cmd)
+			Logs.debug('runner: %r', cmd)
+			Logs.debug('runner_env: kw=%s', kw)
+
+	def exec_command(self, cmd, **kw):
+		"""
+		Runs an external process and returns the exit status::
+
+			def run(tsk):
+				ret = tsk.generator.bld.exec_command('touch foo.txt')
+				return ret
+
+		If the context has the attribute 'log', then captures and logs the process stderr/stdout.
+		Unlike :py:meth:`waflib.Context.Context.cmd_and_log`, this method does not return the
+		stdout/stderr values captured.
+
+		:param cmd: command argument for subprocess.Popen
+		:type cmd: string or list
+		:param kw: keyword arguments for subprocess.Popen. The parameters input/timeout will be passed to wait/communicate.
+		:type kw: dict
+		:returns: process exit status
+		:rtype: integer
+		:raises: :py:class:`waflib.Errors.WafError` if an invalid executable is specified for a non-shell process
+		:raises: :py:class:`waflib.Errors.WafError` in case of execution failure
+		"""
+		subprocess = Utils.subprocess
+		kw['shell'] = isinstance(cmd, str)
+		self.log_command(cmd, kw)
+
+		if self.logger:
+			self.logger.info(cmd)
+
+		if 'stdout' not in kw:
+			kw['stdout'] = subprocess.PIPE
+		if 'stderr' not in kw:
+			kw['stderr'] = subprocess.PIPE
+
+		if Logs.verbose and not kw['shell'] and not Utils.check_exe(cmd[0]):
+			raise Errors.WafError('Program %s not found!' % cmd[0])
+
+		cargs = {}
+		if 'timeout' in kw:
+			if sys.hexversion >= 0x3030000:
+				cargs['timeout'] = kw['timeout']
+				if not 'start_new_session' in kw:
+					kw['start_new_session'] = True
+			del kw['timeout']
+		if 'input' in kw:
+			if kw['input']:
+				cargs['input'] = kw['input']
+				kw['stdin'] = subprocess.PIPE
+			del kw['input']
+
+		if 'cwd' in kw:
+			if not isinstance(kw['cwd'], str):
+				kw['cwd'] = kw['cwd'].abspath()
+
+		encoding = kw.pop('decode_as', default_encoding)
+
+		try:
+			ret, out, err = Utils.run_process(cmd, kw, cargs)
+		except Exception as e:
+			raise Errors.WafError('Execution failure: %s' % str(e), ex=e)
+
+		if out:
+			if not isinstance(out, str):
+				out = out.decode(encoding, errors='replace')
+			if self.logger:
+				self.logger.debug('out: %s', out)
+			else:
+				Logs.info(out, extra={'stream':sys.stdout, 'c1': ''})
+		if err:
+			if not isinstance(err, str):
+				err = err.decode(encoding, errors='replace')
+			if self.logger:
+				self.logger.error('err: %s' % err)
+			else:
+				Logs.info(err, extra={'stream':sys.stderr, 'c1': ''})
+
+		return ret
+
+	def cmd_and_log(self, cmd, **kw):
+		"""
+		Executes a process and returns stdout/stderr if the execution is successful.
+		An exception is thrown when the exit status is non-0. In that case, both stderr and stdout
+		will be bound to the WafError object (configuration tests)::
+
+			def configure(conf):
+				out = conf.cmd_and_log(['echo', 'hello'], output=waflib.Context.STDOUT, quiet=waflib.Context.BOTH)
+				(out, err) = conf.cmd_and_log(['echo', 'hello'], output=waflib.Context.BOTH)
+				(out, err) = conf.cmd_and_log(cmd, input='\\n'.encode(), output=waflib.Context.STDOUT)
+				try:
+					conf.cmd_and_log(['which', 'someapp'], output=waflib.Context.BOTH)
+				except Errors.WafError as e:
+					print(e.stdout, e.stderr)
+
+		:param cmd: args for subprocess.Popen
+		:type cmd: list or string
+		:param kw: keyword arguments for subprocess.Popen. The parameters input/timeout will be passed to wait/communicate.
+		:type kw: dict
+		:returns: a tuple containing the contents of stdout and stderr
+		:rtype: string
+		:raises: :py:class:`waflib.Errors.WafError` if an invalid executable is specified for a non-shell process
+		:raises: :py:class:`waflib.Errors.WafError` in case of execution failure; stdout/stderr/returncode are bound to the exception object
+		"""
+		subprocess = Utils.subprocess
+		kw['shell'] = isinstance(cmd, str)
+		self.log_command(cmd, kw)
+
+		quiet = kw.pop('quiet', None)
+		to_ret = kw.pop('output', STDOUT)
+
+		if Logs.verbose and not kw['shell'] and not Utils.check_exe(cmd[0]):
+			raise Errors.WafError('Program %r not found!' % cmd[0])
+
+		kw['stdout'] = kw['stderr'] = subprocess.PIPE
+		if quiet is None:
+			self.to_log(cmd)
+
+		cargs = {}
+		if 'timeout' in kw:
+			if sys.hexversion >= 0x3030000:
+				cargs['timeout'] = kw['timeout']
+				if not 'start_new_session' in kw:
+					kw['start_new_session'] = True
+			del kw['timeout']
+		if 'input' in kw:
+			if kw['input']:
+				cargs['input'] = kw['input']
+				kw['stdin'] = subprocess.PIPE
+			del kw['input']
+
+		if 'cwd' in kw:
+			if not isinstance(kw['cwd'], str):
+				kw['cwd'] = kw['cwd'].abspath()
+
+		encoding = kw.pop('decode_as', default_encoding)
+
+		try:
+			ret, out, err = Utils.run_process(cmd, kw, cargs)
+		except Exception as e:
+			raise Errors.WafError('Execution failure: %s' % str(e), ex=e)
+
+		if not isinstance(out, str):
+			out = out.decode(encoding, errors='replace')
+		if not isinstance(err, str):
+			err = err.decode(encoding, errors='replace')
+
+		if out and quiet != STDOUT and quiet != BOTH:
+			self.to_log('out: %s' % out)
+		if err and quiet != STDERR and quiet != BOTH:
+			self.to_log('err: %s' % err)
+
+		if ret:
+			e = Errors.WafError('Command %r returned %r' % (cmd, ret))
+			e.returncode = ret
+			e.stderr = err
+			e.stdout = out
+			raise e
+
+		if to_ret == BOTH:
+			return (out, err)
+		elif to_ret == STDERR:
+			return err
+		return out
+
+	def fatal(self, msg, ex=None):
+		"""
+		Prints an error message in red and stops command execution; this is
+		usually used in the configuration section::
+
+			def configure(conf):
+				conf.fatal('a requirement is missing')
+
+		:param msg: message to display
+		:type msg: string
+		:param ex: optional exception object
+		:type ex: exception
+		:raises: :py:class:`waflib.Errors.ConfigurationError`
+		"""
+		if self.logger:
+			self.logger.info('from %s: %s' % (self.path.abspath(), msg))
+		try:
+			logfile = self.logger.handlers[0].baseFilename
+		except AttributeError:
+			pass
+		else:
+			if os.environ.get('WAF_PRINT_FAILURE_LOG'):
+				# see #1930
+				msg = 'Log from (%s):\n%s\n' % (logfile, Utils.readf(logfile))
+			else:
+				msg = '%s\n(complete log in %s)' % (msg, logfile)
+		raise self.errors.ConfigurationError(msg, ex=ex)
+
+	def to_log(self, msg):
+		"""
+		Logs information to the logger (if present), or to stderr.
+		Empty messages are not printed::
+
+			def build(bld):
+				bld.to_log('starting the build')
+
+		Provide a logger on the context class or override this method if necessary.
+
+		:param msg: message
+		:type msg: string
+		"""
+		if not msg:
+			return
+		if self.logger:
+			self.logger.info(msg)
+		else:
+			sys.stderr.write(str(msg))
+			sys.stderr.flush()
+
+
+	def msg(self, *k, **kw):
+		"""
+		Prints a configuration message of the form ``msg: result``.
+		The second part of the message will be in colors. The output
+		can be disabled easly by setting ``in_msg`` to a positive value::
+
+			def configure(conf):
+				self.in_msg = 1
+				conf.msg('Checking for library foo', 'ok')
+				# no output
+
+		:param msg: message to display to the user
+		:type msg: string
+		:param result: result to display
+		:type result: string or boolean
+		:param color: color to use, see :py:const:`waflib.Logs.colors_lst`
+		:type color: string
+		"""
+		try:
+			msg = kw['msg']
+		except KeyError:
+			msg = k[0]
+
+		self.start_msg(msg, **kw)
+
+		try:
+			result = kw['result']
+		except KeyError:
+			result = k[1]
+
+		color = kw.get('color')
+		if not isinstance(color, str):
+			color = result and 'GREEN' or 'YELLOW'
+
+		self.end_msg(result, color, **kw)
+
+	def start_msg(self, *k, **kw):
+		"""
+		Prints the beginning of a 'Checking for xxx' message. See :py:meth:`waflib.Context.Context.msg`
+		"""
+		if kw.get('quiet'):
+			return
+
+		msg = kw.get('msg') or k[0]
+		try:
+			if self.in_msg:
+				self.in_msg += 1
+				return
+		except AttributeError:
+			self.in_msg = 0
+		self.in_msg += 1
+
+		try:
+			self.line_just = max(self.line_just, len(msg))
+		except AttributeError:
+			self.line_just = max(40, len(msg))
+		for x in (self.line_just * '-', msg):
+			self.to_log(x)
+		Logs.pprint('NORMAL', "%s :" % msg.ljust(self.line_just), sep='')
+
+	def end_msg(self, *k, **kw):
+		"""Prints the end of a 'Checking for' message. See :py:meth:`waflib.Context.Context.msg`"""
+		if kw.get('quiet'):
+			return
+		self.in_msg -= 1
+		if self.in_msg:
+			return
+
+		result = kw.get('result') or k[0]
+
+		defcolor = 'GREEN'
+		if result is True:
+			msg = 'ok'
+		elif not result:
+			msg = 'not found'
+			defcolor = 'YELLOW'
+		else:
+			msg = str(result)
+
+		self.to_log(msg)
+		try:
+			color = kw['color']
+		except KeyError:
+			if len(k) > 1 and k[1] in Logs.colors_lst:
+				# compatibility waf 1.7
+				color = k[1]
+			else:
+				color = defcolor
+		Logs.pprint(color, msg)
+
+	def load_special_tools(self, var, ban=[]):
+		"""
+		Loads third-party extensions modules for certain programming languages
+		by trying to list certain files in the extras/ directory. This method
+		is typically called once for a programming language group, see for
+		example :py:mod:`waflib.Tools.compiler_c`
+
+		:param var: glob expression, for example 'cxx\\_\\*.py'
+		:type var: string
+		:param ban: list of exact file names to exclude
+		:type ban: list of string
+		"""
+		if os.path.isdir(waf_dir):
+			lst = self.root.find_node(waf_dir).find_node('waflib/extras').ant_glob(var)
+			for x in lst:
+				if not x.name in ban:
+					load_tool(x.name.replace('.py', ''))
+		else:
+			from zipfile import PyZipFile
+			waflibs = PyZipFile(waf_dir)
+			lst = waflibs.namelist()
+			for x in lst:
+				if not re.match('waflib/extras/%s' % var.replace('*', '.*'), var):
+					continue
+				f = os.path.basename(x)
+				doban = False
+				for b in ban:
+					r = b.replace('*', '.*')
+					if re.match(r, f):
+						doban = True
+				if not doban:
+					f = f.replace('.py', '')
+					load_tool(f)
+
+cache_modules = {}
+"""
+Dictionary holding already loaded modules (wscript), indexed by their absolute path.
+The modules are added automatically by :py:func:`waflib.Context.load_module`
+"""
+
+def load_module(path, encoding=None):
+	"""
+	Loads a wscript file as a python module. This method caches results in :py:attr:`waflib.Context.cache_modules`
+
+	:param path: file path
+	:type path: string
+	:return: Loaded Python module
+	:rtype: module
+	"""
+	try:
+		return cache_modules[path]
+	except KeyError:
+		pass
+
+	module = imp.new_module(WSCRIPT_FILE)
+	try:
+		code = Utils.readf(path, m='r', encoding=encoding)
+	except EnvironmentError:
+		raise Errors.WafError('Could not read the file %r' % path)
+
+	module_dir = os.path.dirname(path)
+	sys.path.insert(0, module_dir)
+	try:
+		exec(compile(code, path, 'exec'), module.__dict__)
+	finally:
+		sys.path.remove(module_dir)
+
+	cache_modules[path] = module
+	return module
+
+def load_tool(tool, tooldir=None, ctx=None, with_sys_path=True):
+	"""
+	Imports a Waf tool as a python module, and stores it in the dict :py:const:`waflib.Context.Context.tools`
+
+	:type  tool: string
+	:param tool: Name of the tool
+	:type  tooldir: list
+	:param tooldir: List of directories to search for the tool module
+	:type  with_sys_path: boolean
+	:param with_sys_path: whether or not to search the regular sys.path, besides waf_dir and potentially given tooldirs
+	"""
+	if tool == 'java':
+		tool = 'javaw' # jython
+	else:
+		tool = tool.replace('++', 'xx')
+
+	if not with_sys_path:
+		back_path = sys.path
+		sys.path = []
+	try:
+		if tooldir:
+			assert isinstance(tooldir, list)
+			sys.path = tooldir + sys.path
+			try:
+				__import__(tool)
+			except ImportError as e:
+				e.waf_sys_path = list(sys.path)
+				raise
+			finally:
+				for d in tooldir:
+					sys.path.remove(d)
+			ret = sys.modules[tool]
+			Context.tools[tool] = ret
+			return ret
+		else:
+			if not with_sys_path:
+				sys.path.insert(0, waf_dir)
+			try:
+				for x in ('waflib.Tools.%s', 'waflib.extras.%s', 'waflib.%s', '%s'):
+					try:
+						__import__(x % tool)
+						break
+					except ImportError:
+						x = None
+				else: # raise an exception
+					__import__(tool)
+			except ImportError as e:
+				e.waf_sys_path = list(sys.path)
+				raise
+			finally:
+				if not with_sys_path:
+					sys.path.remove(waf_dir)
+			ret = sys.modules[x % tool]
+			Context.tools[tool] = ret
+			return ret
+	finally:
+		if not with_sys_path:
+			sys.path += back_path
+