path: root/mesonbuild/mesonlib.py

# Copyright 2012-2020 The Meson development team

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""A library of random helper functionality."""
from ._pathlib import Path
import sys
import stat
import time
import platform, subprocess, operator, os, shlex, shutil, re
import collections
from enum import IntEnum
from functools import lru_cache, wraps
from itertools import tee, filterfalse
import typing as T
import uuid
import textwrap

from mesonbuild import mlog

if T.TYPE_CHECKING:
    from .build import ConfigurationData
    from .coredata import OptionDictType, UserOption
    from .compilers.compilers import CompilerType
    from .interpreterbase import ObjectHolder

    FileOrString = T.Union['File', str]

_T = T.TypeVar('_T')
_U = T.TypeVar('_U')

have_fcntl = False
have_msvcrt = False
# TODO: this is such a hack, this really should be either in coredata or in the
# interpreter
# {subproject: project_meson_version}
project_meson_versions = collections.defaultdict(str)  # type: T.DefaultDict[str, str]

try:
    import fcntl
    have_fcntl = True
except Exception:
    pass

try:
    import msvcrt
    have_msvcrt = True
except Exception:
    pass

from glob import glob

if os.path.basename(sys.executable) == 'meson.exe':
    # In Windows and using the MSI installed executable.
    python_command = [sys.executable, 'runpython']
else:
    python_command = [sys.executable]
meson_command = None

class MesonException(Exception):
    '''Exceptions thrown by Meson'''

    file = None    # type: T.Optional[str]
    lineno = None  # type: T.Optional[int]
    colno = None   # type: T.Optional[int]

class EnvironmentException(MesonException):
    '''Exceptions thrown while processing and creating the build environment'''

class GitException(MesonException):
    def __init__(self, msg: str, output: T.Optional[str] = None):
        super().__init__(msg)
        self.output = output.strip() if output else ''

GIT = shutil.which('git')
def git(cmd: T.List[str], workingdir: str, check: bool = False, **kwargs: T.Any) -> T.Tuple[subprocess.Popen, str, str]:
    cmd = [GIT] + cmd
    p, o, e = Popen_safe(cmd, cwd=workingdir, **kwargs)
    if check and p.returncode != 0:
        raise GitException('Git command failed: ' + str(cmd), e)
    return p, o, e

def quiet_git(cmd: T.List[str], workingdir: str, check: bool = False) -> T.Tuple[bool, str]:
    if not GIT:
        m = 'Git program not found.'
        if check:
            raise GitException(m)
        return False, m
    p, o, e = git(cmd, workingdir, check)
    if p.returncode != 0:
        return False, e
    return True, o

def verbose_git(cmd: T.List[str], workingdir: str, check: bool = False) -> bool:
    if not GIT:
        m = 'Git program not found.'
        if check:
            raise GitException(m)
        return False
    p, _, _ = git(cmd, workingdir, check, stdout=None, stderr=None)
    return p.returncode == 0

def set_meson_command(mainfile: str) -> None:
    global python_command
    global meson_command
    # On UNIX-like systems `meson` is a Python script
    # On Windows `meson` and `meson.exe` are wrapper exes
    if not mainfile.endswith('.py'):
        meson_command = [mainfile]
    elif os.path.isabs(mainfile) and mainfile.endswith('mesonmain.py'):
        # Can't actually run meson with an absolute path to mesonmain.py, it must be run as -m mesonbuild.mesonmain
        meson_command = python_command + ['-m', 'mesonbuild.mesonmain']
    else:
        # Either run uninstalled, or full path to meson-script.py
        meson_command = python_command + [mainfile]
    # We print this value for unit tests.
    if 'MESON_COMMAND_TESTS' in os.environ:
        mlog.log('meson_command is {!r}'.format(meson_command))


def is_ascii_string(astring: T.Union[str, bytes]) -> bool:
    try:
        if isinstance(astring, str):
            astring.encode('ascii')
        elif isinstance(astring, bytes):
            astring.decode('ascii')
    except UnicodeDecodeError:
        return False
    return True


def check_direntry_issues(direntry_array: T.Union[T.List[T.Union[str, bytes]], str, bytes]) -> None:
    import locale
    # Warn if the locale is not UTF-8. This can cause various unfixable issues
    # such as os.stat not being able to decode filenames with unicode in them.
    # There is no way to reset both the preferred encoding and the filesystem
    # encoding, so we can just warn about it.
    e = locale.getpreferredencoding()
    if e.upper() != 'UTF-8' and not is_windows():
        if not isinstance(direntry_array, list):
            direntry_array = [direntry_array]
        for de in direntry_array:
            if is_ascii_string(de):
                continue
            mlog.warning(textwrap.dedent('''
                You are using {!r} which is not a Unicode-compatible
                locale but you are trying to access a file system entry called {!r} which is
                not pure ASCII. This may cause problems.
                '''.format(e, de)), file=sys.stderr)


# Put this in objects that should not get dumped to pickle files
# by accident.
import threading
an_unpicklable_object = threading.Lock()

class FileMode:
    # The first triad is for owner permissions, the second for group permissions,
    # and the third for others (everyone else).
    # For the 1st character:
    #  'r' means can read
    #  '-' means not allowed
    # For the 2nd character:
    #  'w' means can write
    #  '-' means not allowed
    # For the 3rd character:
    #  'x' means can execute
    #  's' means can execute and setuid/setgid is set (owner/group triads only)
    #  'S' means cannot execute and setuid/setgid is set (owner/group triads only)
    #  't' means can execute and sticky bit is set ("others" triads only)
    #  'T' means cannot execute and sticky bit is set ("others" triads only)
    #  '-' means none of these are allowed
    #
    # The meanings of 'rwx' perms is not obvious for directories; see:
    # https://www.hackinglinuxexposed.com/articles/20030424.html
    #
    # For information on this notation such as setuid/setgid/sticky bits, see:
    # https://en.wikipedia.org/wiki/File_system_permissions#Symbolic_notation
    symbolic_perms_regex = re.compile('[r-][w-][xsS-]' # Owner perms
                                      '[r-][w-][xsS-]' # Group perms
                                      '[r-][w-][xtT-]') # Others perms

    def __init__(self, perms: T.Optional[str] = None, owner: T.Optional[str] = None,
                 group: T.Optional[str] = None):
        self.perms_s = perms
        self.perms = self.perms_s_to_bits(perms)
        self.owner = owner
        self.group = group

    def __repr__(self) -> str:
        ret = '<FileMode: {!r} owner={} group={}'
        return ret.format(self.perms_s, self.owner, self.group)

    @classmethod
    def perms_s_to_bits(cls, perms_s: T.Optional[str]) -> int:
        '''
        Does the opposite of stat.filemode(), converts strings of the form
        'rwxr-xr-x' to st_mode enums which can be passed to os.chmod()
        '''
        if perms_s is None:
            # No perms specified, we will not touch the permissions
            return -1
        eg = 'rwxr-xr-x'
        if not isinstance(perms_s, str):
            msg = 'Install perms must be a string. For example, {!r}'
            raise MesonException(msg.format(eg))
        if len(perms_s) != 9 or not cls.symbolic_perms_regex.match(perms_s):
            msg = 'File perms {!r} must be exactly 9 chars. For example, {!r}'
            raise MesonException(msg.format(perms_s, eg))
        perms = 0
        # Owner perms
        if perms_s[0] == 'r':
            perms |= stat.S_IRUSR
        if perms_s[1] == 'w':
            perms |= stat.S_IWUSR
        if perms_s[2] == 'x':
            perms |= stat.S_IXUSR
        elif perms_s[2] == 'S':
            perms |= stat.S_ISUID
        elif perms_s[2] == 's':
            perms |= stat.S_IXUSR
            perms |= stat.S_ISUID
        # Group perms
        if perms_s[3] == 'r':
            perms |= stat.S_IRGRP
        if perms_s[4] == 'w':
            perms |= stat.S_IWGRP
        if perms_s[5] == 'x':
            perms |= stat.S_IXGRP
        elif perms_s[5] == 'S':
            perms |= stat.S_ISGID
        elif perms_s[5] == 's':
            perms |= stat.S_IXGRP
            perms |= stat.S_ISGID
        # Others perms
        if perms_s[6] == 'r':
            perms |= stat.S_IROTH
        if perms_s[7] == 'w':
            perms |= stat.S_IWOTH
        if perms_s[8] == 'x':
            perms |= stat.S_IXOTH
        elif perms_s[8] == 'T':
            perms |= stat.S_ISVTX
        elif perms_s[8] == 't':
            perms |= stat.S_IXOTH
            perms |= stat.S_ISVTX
        return perms

class File:
    def __init__(self, is_built: bool, subdir: str, fname: str):
        self.is_built = is_built
        self.subdir = subdir
        self.fname = fname
        self.hash = hash((is_built, subdir, fname))

    def __str__(self) -> str:
        return self.relative_name()

    def __repr__(self) -> str:
        ret = '<File: {0}'
        if not self.is_built:
            ret += ' (not built)'
        ret += '>'
        return ret.format(self.relative_name())

    @staticmethod
    @lru_cache(maxsize=None)
    def from_source_file(source_root: str, subdir: str, fname: str) -> 'File':
        if not os.path.isfile(os.path.join(source_root, subdir, fname)):
            raise MesonException('File %s does not exist.' % fname)
        return File(False, subdir, fname)

    @staticmethod
    def from_built_file(subdir: str, fname: str) -> 'File':
        return File(True, subdir, fname)

    @staticmethod
    def from_absolute_file(fname: str) -> 'File':
        return File(False, '', fname)

    @lru_cache(maxsize=None)
    def rel_to_builddir(self, build_to_src: str) -> str:
        if self.is_built:
            return self.relative_name()
        else:
            return os.path.join(build_to_src, self.subdir, self.fname)

    @lru_cache(maxsize=None)
    def absolute_path(self, srcdir: str, builddir: str) -> str:
        absdir = srcdir
        if self.is_built:
            absdir = builddir
        return os.path.join(absdir, self.relative_name())

    def endswith(self, ending: str) -> bool:
        return self.fname.endswith(ending)

    def split(self, s: str) -> T.List[str]:
        return self.fname.split(s)

    def __eq__(self, other: object) -> bool:
        if not isinstance(other, File):
            return NotImplemented
        if self.hash != other.hash:
            return False
        return (self.fname, self.subdir, self.is_built) == (other.fname, other.subdir, other.is_built)

    def __hash__(self) -> int:
        return self.hash

    @lru_cache(maxsize=None)
    def relative_name(self) -> str:
        return os.path.join(self.subdir, self.fname)


def get_compiler_for_source(compilers: T.Iterable['CompilerType'], src: str) -> 'CompilerType':
    """Given a set of compilers and a source, find the compiler for that source type."""
    for comp in compilers:
        if comp.can_compile(src):
            return comp
    raise MesonException('No specified compiler can handle file {!s}'.format(src))


def classify_unity_sources(compilers: T.Iterable['CompilerType'], sources: T.Iterable[str]) -> T.Dict['CompilerType', T.List[str]]:
    compsrclist = {}  # type: T.Dict[CompilerType, T.List[str]]
    for src in sources:
        comp = get_compiler_for_source(compilers, src)
        if comp not in compsrclist:
            compsrclist[comp] = [src]
        else:
            compsrclist[comp].append(src)
    return compsrclist


class MachineChoice(IntEnum):

    """Enum class representing one of the two abstract machine names used in
    most places: the build, and host, machines.
    """

    BUILD = 0
    HOST = 1

    def get_lower_case_name(self) -> str:
        return PerMachine('build', 'host')[self]

    def get_prefix(self) -> str:
        return PerMachine('build.', '')[self]


class PerMachine(T.Generic[_T]):
    def __init__(self, build: _T, host: _T) -> None:
        self.build = build
        self.host = host

    def __getitem__(self, machine: MachineChoice) -> _T:
        return {
            MachineChoice.BUILD:  self.build,
            MachineChoice.HOST:   self.host,
        }[machine]

    def __setitem__(self, machine: MachineChoice, val: _T) -> None:
        setattr(self, machine.get_lower_case_name(), val)

    def miss_defaulting(self) -> "PerMachineDefaultable[T.Optional[_T]]":
        """Unset definition duplicated from their previous to None

        This is the inverse of ''default_missing''. By removing defaulted
        machines, we can elaborate the original and then redefault them and thus
        avoid repeating the elaboration explicitly.
        """
        unfreeze = PerMachineDefaultable() # type: PerMachineDefaultable[T.Optional[_T]]
        unfreeze.build = self.build
        unfreeze.host = self.host
        if unfreeze.host == unfreeze.build:
            unfreeze.host = None
        return unfreeze

    def __repr__(self) -> str:
        return 'PerMachine({!r}, {!r})'.format(self.build, self.host)


class PerThreeMachine(PerMachine[_T]):
    """Like `PerMachine` but includes `target` too.

    It turns out just one thing do we need track the target machine. There's no
    need to computer the `target` field so we don't bother overriding the
    `__getitem__`/`__setitem__` methods.
    """
    def __init__(self, build: _T, host: _T, target: _T) -> None:
        super().__init__(build, host)
        self.target = target

    def miss_defaulting(self) -> "PerThreeMachineDefaultable[T.Optional[_T]]":
        """Unset definition duplicated from their previous to None

        This is the inverse of ''default_missing''. By removing defaulted
        machines, we can elaborate the original and then redefault them and thus
        avoid repeating the elaboration explicitly.
        """
        unfreeze = PerThreeMachineDefaultable() # type: PerThreeMachineDefaultable[T.Optional[_T]]
        unfreeze.build = self.build
        unfreeze.host = self.host
        unfreeze.target = self.target
        if unfreeze.target == unfreeze.host:
            unfreeze.target = None
        if unfreeze.host == unfreeze.build:
            unfreeze.host = None
        return unfreeze

    def matches_build_machine(self, machine: MachineChoice) -> bool:
        return self.build == self[machine]

    def __repr__(self) -> str:
        return 'PerThreeMachine({!r}, {!r}, {!r})'.format(self.build, self.host, self.target)


class PerMachineDefaultable(PerMachine[T.Optional[_T]]):
    """Extends `PerMachine` with the ability to default from `None`s.
    """
    def __init__(self) -> None:
        super().__init__(None, None)

    def default_missing(self) -> "PerMachine[T.Optional[_T]]":
        """Default host to build

        This allows just specifying nothing in the native case, and just host in the
        cross non-compiler case.
        """
        freeze = PerMachine(self.build, self.host)
        if freeze.host is None:
            freeze.host = freeze.build
        return freeze

    def __repr__(self) -> str:
        return 'PerMachineDefaultable({!r}, {!r})'.format(self.build, self.host)


class PerThreeMachineDefaultable(PerMachineDefaultable, PerThreeMachine[T.Optional[_T]]):
    """Extends `PerThreeMachine` with the ability to default from `None`s.
    """
    def __init__(self) -> None:
        PerThreeMachine.__init__(self, None, None, None)

    def default_missing(self) -> "PerThreeMachine[T.Optional[_T]]":
        """Default host to build and target to host.

        This allows just specifying nothing in the native case, just host in the
        cross non-compiler case, and just target in the native-built
        cross-compiler case.
        """
        freeze = PerThreeMachine(self.build, self.host, self.target)
        if freeze.host is None:
            freeze.host = freeze.build
        if freeze.target is None:
            freeze.target = freeze.host
        return freeze

    def __repr__(self) -> str:
        return 'PerThreeMachineDefaultable({!r}, {!r}, {!r})'.format(self.build, self.host, self.target)


def is_sunos() -> bool:
    return platform.system().lower() == 'sunos'


def is_osx() -> bool:
    return platform.system().lower() == 'darwin'


def is_linux() -> bool:
    return platform.system().lower() == 'linux'


def is_android() -> bool:
    return platform.system().lower() == 'android'


def is_haiku() -> bool:
    return platform.system().lower() == 'haiku'


def is_openbsd() -> bool:
    return platform.system().lower() == 'openbsd'


def is_windows() -> bool:
    platname = platform.system().lower()
    return platname == 'windows'


def is_cygwin() -> bool:
    return sys.platform == 'cygwin'


def is_debianlike() -> bool:
    return os.path.isfile('/etc/debian_version')


def is_dragonflybsd() -> bool:
    return platform.system().lower() == 'dragonfly'


def is_netbsd() -> bool:
    return platform.system().lower() == 'netbsd'


def is_freebsd() -> bool:
    return platform.system().lower() == 'freebsd'

def is_irix() -> bool:
    return platform.system().startswith('irix')

def is_hurd() -> bool:
    return platform.system().lower() == 'gnu'

def is_qnx() -> bool:
    return platform.system().lower() == 'qnx'

def is_aix() -> bool:
    return platform.system().lower() == 'aix'

def exe_exists(arglist: T.List[str]) -> bool:
    try:
        if subprocess.run(arglist, timeout=10).returncode == 0:
            return True
    except (FileNotFoundError, subprocess.TimeoutExpired):
        pass
    return False


@lru_cache(maxsize=None)
def darwin_get_object_archs(objpath: str) -> T.List[str]:
    '''
    For a specific object (executable, static library, dylib, etc), run `lipo`
    to fetch the list of archs supported by it. Supports both thin objects and
    'fat' objects.
    '''
    _, stdo, stderr = Popen_safe(['lipo', '-info', objpath])
    if not stdo:
        mlog.debug('lipo {}: {}'.format(objpath, stderr))
        return None
    stdo = stdo.rsplit(': ', 1)[1]
    # Convert from lipo-style archs to meson-style CPUs
    stdo = stdo.replace('i386', 'x86')
    stdo = stdo.replace('arm64', 'aarch64')
    # Add generic name for armv7 and armv7s
    if 'armv7' in stdo:
        stdo += ' arm'
    return stdo.split()


def detect_vcs(source_dir: T.Union[str, Path]) -> T.Optional[T.Dict[str, str]]:
    vcs_systems = [
        dict(name = 'git',        cmd = 'git', repo_dir = '.git', get_rev = 'git describe --dirty=+', rev_regex = '(.*)', dep = '.git/logs/HEAD'),
        dict(name = 'mercurial',  cmd = 'hg',  repo_dir = '.hg',  get_rev = 'hg id -i',               rev_regex = '(.*)', dep = '.hg/dirstate'),
        dict(name = 'subversion', cmd = 'svn', repo_dir = '.svn', get_rev = 'svn info',               rev_regex = 'Revision: (.*)', dep = '.svn/wc.db'),
        dict(name = 'bazaar',     cmd = 'bzr', repo_dir = '.bzr', get_rev = 'bzr revno',              rev_regex = '(.*)', dep = '.bzr'),
    ]
    if isinstance(source_dir, str):
        source_dir = Path(source_dir)

    parent_paths_and_self = collections.deque(source_dir.parents)
    # Prepend the source directory to the front so we can check it;
    # source_dir.parents doesn't include source_dir
    parent_paths_and_self.appendleft(source_dir)
    for curdir in parent_paths_and_self:
        for vcs in vcs_systems:
            if Path.is_dir(curdir.joinpath(vcs['repo_dir'])) and shutil.which(vcs['cmd']):
                vcs['wc_dir'] = str(curdir)
                return vcs
    return None

# a helper class which implements the same version ordering as RPM
class Version:
    def __init__(self, s: str) -> None:
        self._s = s

        # split into numeric, alphabetic and non-alphanumeric sequences
        sequences1 = re.finditer(r'(\d+|[a-zA-Z]+|[^a-zA-Z\d]+)', s)

        # non-alphanumeric separators are discarded
        sequences2 = [m for m in sequences1 if not re.match(r'[^a-zA-Z\d]+', m.group(1))]

        # numeric sequences are converted from strings to ints
        sequences3 = [int(m.group(1)) if m.group(1).isdigit() else m.group(1) for m in sequences2]

        self._v = sequences3

    def __str__(self) -> str:
        return '%s (V=%s)' % (self._s, str(self._v))

    def __repr__(self) -> str:
        return '<Version: {}>'.format(self._s)

    def __lt__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self.__cmp(other, operator.lt)
        return NotImplemented

    def __gt__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self.__cmp(other, operator.gt)
        return NotImplemented

    def __le__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self.__cmp(other, operator.le)
        return NotImplemented

    def __ge__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self.__cmp(other, operator.ge)
        return NotImplemented

    def __eq__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self._v == other._v
        return NotImplemented

    def __ne__(self, other: object) -> bool:
        if isinstance(other, Version):
            return self._v != other._v
        return NotImplemented

    def __cmp(self, other: 'Version', comparator: T.Callable[[T.Any, T.Any], bool]) -> bool:
        # compare each sequence in order
        for ours, theirs in zip(self._v, other._v):
            # sort a non-digit sequence before a digit sequence
            ours_is_int = isinstance(ours, int)
            theirs_is_int = isinstance(theirs, int)
            if ours_is_int != theirs_is_int:
                return comparator(ours_is_int, theirs_is_int)

            if ours != theirs:
                return comparator(ours, theirs)

        # if equal length, all components have matched, so equal
        # otherwise, the version with a suffix remaining is greater
        return comparator(len(self._v), len(other._v))


def _version_extract_cmpop(vstr2: str) -> T.Tuple[T.Callable[[T.Any, T.Any], bool], str]:
    if vstr2.startswith('>='):
        cmpop = operator.ge
        vstr2 = vstr2[2:]
    elif vstr2.startswith('<='):
        cmpop = operator.le
        vstr2 = vstr2[2:]
    elif vstr2.startswith('!='):
        cmpop = operator.ne
        vstr2 = vstr2[2:]
    elif vstr2.startswith('=='):
        cmpop = operator.eq
        vstr2 = vstr2[2:]
    elif vstr2.startswith('='):
        cmpop = operator.eq
        vstr2 = vstr2[1:]
    elif vstr2.startswith('>'):
        cmpop = operator.gt
        vstr2 = vstr2[1:]
    elif vstr2.startswith('<'):
        cmpop = operator.lt
        vstr2 = vstr2[1:]
    else:
        cmpop = operator.eq

    return (cmpop, vstr2)


def version_compare(vstr1: str, vstr2: str) -> bool:
    (cmpop, vstr2) = _version_extract_cmpop(vstr2)
    return cmpop(Version(vstr1), Version(vstr2))


def version_compare_many(vstr1: str, conditions: T.Union[str, T.Iterable[str]]) -> T.Tuple[bool, T.List[str], T.List[str]]:
    if isinstance(conditions, str):
        conditions = [conditions]
    found = []
    not_found = []
    for req in conditions:
        if not version_compare(vstr1, req):
            not_found.append(req)
        else:
            found.append(req)
    return not_found == [], not_found, found


# determine if the minimum version satisfying the condition |condition| exceeds
# the minimum version for a feature |minimum|
def version_compare_condition_with_min(condition: str, minimum: str) -> bool:
    if condition.startswith('>='):
        cmpop = operator.le
        condition = condition[2:]
    elif condition.startswith('<='):
        return False
    elif condition.startswith('!='):
        return False
    elif condition.startswith('=='):
        cmpop = operator.le
        condition = condition[2:]
    elif condition.startswith('='):
        cmpop = operator.le
        condition = condition[1:]
    elif condition.startswith('>'):
        cmpop = operator.lt
        condition = condition[1:]
    elif condition.startswith('<'):
        return False
    else:
        cmpop = operator.le

    # Declaring a project(meson_version: '>=0.46') and then using features in
    # 0.46.0 is valid, because (knowing the meson versioning scheme) '0.46.0' is
    # the lowest version which satisfies the constraint '>=0.46'.
    #
    # But this will fail here, because the minimum version required by the
    # version constraint ('0.46') is strictly less (in our version comparison)
    # than the minimum version needed for the feature ('0.46.0').
    #
    # Map versions in the constraint of the form '0.46' to '0.46.0', to embed
    # this knowledge of the meson versioning scheme.
    condition = condition.strip()
    if re.match(r'^\d+.\d+$', condition):
        condition += '.0'

    return T.cast(bool, cmpop(Version(minimum), Version(condition)))


def default_libdir() -> str:
    if is_debianlike():
        try:
            pc = subprocess.Popen(['dpkg-architecture', '-qDEB_HOST_MULTIARCH'],
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.DEVNULL)
            (stdo, _) = pc.communicate()
            if pc.returncode == 0:
                archpath = stdo.decode().strip()
                return 'lib/' + archpath
        except Exception:
            pass
    if is_freebsd() or is_irix():
        return 'lib'
    if os.path.isdir('/usr/lib64') and not os.path.islink('/usr/lib64'):
        return 'lib64'
    return 'lib'


def default_libexecdir() -> str:
    # There is no way to auto-detect this, so it must be set at build time
    return 'libexec'


def default_prefix() -> str:
    return 'c:/' if is_windows() else '/usr/local'


def get_library_dirs() -> T.List[str]:
    if is_windows():
        return ['C:/mingw/lib'] # TODO: get programmatically
    if is_osx():
        return ['/usr/lib'] # TODO: get programmatically
    # The following is probably Debian/Ubuntu specific.
    # /usr/local/lib is first because it contains stuff
    # installed by the sysadmin and is probably more up-to-date
    # than /usr/lib. If you feel that this search order is
    # problematic, please raise the issue on the mailing list.
    unixdirs = ['/usr/local/lib', '/usr/lib', '/lib']

    if is_freebsd():
        return unixdirs
    # FIXME: this needs to be further genericized for aarch64 etc.
    machine = platform.machine()
    if machine in ('i386', 'i486', 'i586', 'i686'):
        plat = 'i386'
    elif machine.startswith('arm'):
        plat = 'arm'
    else:
        plat = ''

    # Solaris puts 32-bit libraries in the main /lib & /usr/lib directories
    # and 64-bit libraries in platform specific subdirectories.
    if is_sunos():
        if machine == 'i86pc':
            plat = 'amd64'
        elif machine.startswith('sun4'):
            plat = 'sparcv9'

    usr_platdir = Path('/usr/lib/') / plat
    if usr_platdir.is_dir():
        unixdirs += [str(x) for x in (usr_platdir).iterdir() if x.is_dir()]
    if os.path.exists('/usr/lib64'):
        unixdirs.append('/usr/lib64')

    lib_platdir = Path('/lib/') / plat
    if lib_platdir.is_dir():
        unixdirs += [str(x) for x in (lib_platdir).iterdir() if x.is_dir()]
    if os.path.exists('/lib64'):
        unixdirs.append('/lib64')

    return unixdirs


def has_path_sep(name: str, sep: str = '/\\') -> bool:
    'Checks if any of the specified @sep path separators are in @name'
    for each in sep:
        if each in name:
            return True
    return False


if is_windows():
    # shlex.split is not suitable for splitting command line on Window (https://bugs.python.org/issue1724822);
    # shlex.quote is similarly problematic. Below are "proper" implementations of these functions according to
    # https://docs.microsoft.com/en-us/cpp/c-language/parsing-c-command-line-arguments and
    # https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/

    _whitespace = ' \t\n\r'
    _find_unsafe_char = re.compile(r'[{}"]'.format(_whitespace)).search

    def quote_arg(arg: str) -> str:
        if arg and not _find_unsafe_char(arg):
            return arg

        result = '"'
        num_backslashes = 0
        for c in arg:
            if c == '\\':
                num_backslashes += 1
            else:
                if c == '"':
                    # Escape all backslashes and the following double quotation mark
                    num_backslashes = num_backslashes * 2 + 1

                result += num_backslashes * '\\' + c
                num_backslashes = 0

        # Escape all backslashes, but let the terminating double quotation
        # mark we add below be interpreted as a metacharacter
        result += (num_backslashes * 2) * '\\' + '"'
        return result

    def split_args(cmd: str) -> T.List[str]:
        result = []
        arg = ''
        num_backslashes = 0
        num_quotes = 0
        in_quotes = False
        for c in cmd:
            if c == '\\':
                num_backslashes += 1
            else:
                if c == '"' and not (num_backslashes % 2):
                    # unescaped quote, eat it
                    arg += (num_backslashes // 2) * '\\'
                    num_quotes += 1
                    in_quotes = not in_quotes
                elif c in _whitespace and not in_quotes:
                    if arg or num_quotes:
                        # reached the end of the argument
                        result.append(arg)
                        arg = ''
                        num_quotes = 0
                else:
                    if c == '"':
                        # escaped quote
                        num_backslashes = (num_backslashes - 1) // 2

                    arg += num_backslashes * '\\' + c

                num_backslashes = 0

        if arg or num_quotes:
            result.append(arg)

        return result
else:
    def quote_arg(arg: str) -> str:
        return shlex.quote(arg)

    def split_args(cmd: str) -> T.List[str]:
        return shlex.split(cmd)


def join_args(args: T.Iterable[str]) -> str:
    return ' '.join([quote_arg(x) for x in args])


def do_replacement(regex: T.Pattern[str], line: str, variable_format: str,
                   confdata: 'ConfigurationData') -> T.Tuple[str, T.Set[str]]:
    missing_variables = set()  # type: T.Set[str]
    if variable_format == 'cmake':
        start_tag = '${'
        backslash_tag = '\\${'
    else:
        assert variable_format in ['meson', 'cmake@']
        start_tag = '@'
        backslash_tag = '\\@'

    def variable_replace(match: T.Match[str]) -> str:
        # Pairs of escape characters before '@' or '\@'
        if match.group(0).endswith('\\'):
            num_escapes = match.end(0) - match.start(0)
            return '\\' * (num_escapes // 2)
        # Single escape character and '@'
        elif match.group(0) == backslash_tag:
            return start_tag
        # Template variable to be replaced
        else:
            varname = match.group(1)
            var_str = ''
            if varname in confdata:
                (var, desc) = confdata.get(varname)
                if isinstance(var, str):
                    var_str = var
                elif isinstance(var, int):
                    var_str = str(var)
                else:
                    msg = 'Tried to replace variable {!r} value with ' \
                          'something other than a string or int: {!r}'
                    raise MesonException(msg.format(varname, var))
            else:
                missing_variables.add(varname)
            return var_str
    return re.sub(regex, variable_replace, line), missing_variables

def do_define(regex: T.Pattern[str], line: str, confdata: 'ConfigurationData', variable_format: str) -> str:
    def get_cmake_define(line: str, confdata: 'ConfigurationData') -> str:
        arr = line.split()
        define_value=[]
        for token in arr[2:]:
            try:
                (v, desc) = confdata.get(token)
                define_value += [str(v)]
            except KeyError:
                define_value += [token]
        return ' '.join(define_value)

    arr = line.split()
    if variable_format == 'meson' and len(arr) != 2:
        raise MesonException('#mesondefine does not contain exactly two tokens: %s' % line.strip())

    varname = arr[1]
    try:
        (v, desc) = confdata.get(varname)
    except KeyError:
        return '/* #undef %s */\n' % varname
    if isinstance(v, bool):
        if v:
            return '#define %s\n' % varname
        else:
            return '#undef %s\n' % varname
    elif isinstance(v, int):
        return '#define %s %d\n' % (varname, v)
    elif isinstance(v, str):
        if variable_format == 'meson':
            result = v
        else:
            result = get_cmake_define(line, confdata)
        result = '#define %s %s\n' % (varname, result)
        (result, missing_variable) = do_replacement(regex, result, variable_format, confdata)
        return result
    else:
        raise MesonException('#mesondefine argument "%s" is of unknown type.' % varname)

def get_variable_regex(variable_format: str = 'meson') -> T.Pattern[str]:
    # Only allow (a-z, A-Z, 0-9, _, -) as valid characters for a define
    # Also allow escaping '@' with '\@'
    if variable_format in ['meson', 'cmake@']:
        regex = re.compile(r'(?:\\\\)+(?=\\?@)|\\@|@([-a-zA-Z0-9_]+)@')
    elif variable_format == 'cmake':
        regex = re.compile(r'(?:\\\\)+(?=\\?\$)|\\\${|\${([-a-zA-Z0-9_]+)}')
    else:
        raise MesonException('Format "{}" not handled'.format(variable_format))
    return regex

def do_conf_str (data: list, confdata: 'ConfigurationData', variable_format: str,
                 encoding: str = 'utf-8') -> T.Tuple[T.List[str],T.Set[str], bool]:
    def line_is_valid(line : str, variable_format: str) -> bool:
        if variable_format == 'meson':
            if '#cmakedefine' in line:
                return False
        else: #cmake format
            if '#mesondefine' in line:
                return False
        return True

    regex = get_variable_regex(variable_format)

    search_token = '#mesondefine'
    if variable_format != 'meson':
        search_token = '#cmakedefine'

    result = []
    missing_variables = set()
    # Detect when the configuration data is empty and no tokens were found
    # during substitution so we can warn the user to use the `copy:` kwarg.
    confdata_useless = not confdata.keys()
    for line in data:
        if line.startswith(search_token):
            confdata_useless = False
            line = do_define(regex, line, confdata, variable_format)
        else:
            if not line_is_valid(line,variable_format):
                raise MesonException('Format "{}" mismatched'.format(variable_format))
            line, missing = do_replacement(regex, line, variable_format, confdata)
            missing_variables.update(missing)
            if missing:
                confdata_useless = False
        result.append(line)

    return result, missing_variables, confdata_useless

def do_conf_file(src: str, dst: str, confdata: 'ConfigurationData', variable_format: str,
                 encoding: str = 'utf-8') -> T.Tuple[T.Set[str], bool]:
    try:
        with open(src, encoding=encoding, newline='') as f:
            data = f.readlines()
    except Exception as e:
        raise MesonException('Could not read input file %s: %s' % (src, str(e)))

    (result, missing_variables, confdata_useless) = do_conf_str(data, confdata, variable_format, encoding)
    dst_tmp = dst + '~'
    try:
        with open(dst_tmp, 'w', encoding=encoding, newline='') as f:
            f.writelines(result)
    except Exception as e:
        raise MesonException('Could not write output file %s: %s' % (dst, str(e)))
    shutil.copymode(src, dst_tmp)
    replace_if_different(dst, dst_tmp)
    return missing_variables, confdata_useless

CONF_C_PRELUDE = '''/*
 * Autogenerated by the Meson build system.
 * Do not edit, your changes will be lost.
 */

#pragma once

'''

CONF_NASM_PRELUDE = '''; Autogenerated by the Meson build system.
; Do not edit, your changes will be lost.

'''

def dump_conf_header(ofilename: str, cdata: 'ConfigurationData', output_format: str) -> None:
    if output_format == 'c':
        prelude = CONF_C_PRELUDE
        prefix = '#'
    elif output_format == 'nasm':
        prelude = CONF_NASM_PRELUDE
        prefix = '%'

    ofilename_tmp = ofilename + '~'
    with open(ofilename_tmp, 'w', encoding='utf-8') as ofile:
        ofile.write(prelude)
        for k in sorted(cdata.keys()):
            (v, desc) = cdata.get(k)
            if desc:
                if output_format == 'c':
                    ofile.write('/* %s */\n' % desc)
                elif output_format == 'nasm':
                    for line in desc.split('\n'):
                        ofile.write('; %s\n' % line)
            if isinstance(v, bool):
                if v:
                    ofile.write('%sdefine %s\n\n' % (prefix, k))
                else:
                    ofile.write('%sundef %s\n\n' % (prefix, k))
            elif isinstance(v, (int, str)):
                ofile.write('%sdefine %s %s\n\n' % (prefix, k, v))
            else:
                raise MesonException('Unknown data type in configuration file entry: ' + k)
    replace_if_different(ofilename, ofilename_tmp)


def replace_if_different(dst: str, dst_tmp: str) -> None:
    # If contents are identical, don't touch the file to prevent
    # unnecessary rebuilds.
    different = True
    try:
        with open(dst, 'rb') as f1, open(dst_tmp, 'rb') as f2:
            if f1.read() == f2.read():
                different = False
    except FileNotFoundError:
        pass
    if different:
        os.replace(dst_tmp, dst)
    else:
        os.unlink(dst_tmp)


@T.overload
def unholder(item: 'ObjectHolder[_T]') -> _T: ...

@T.overload
def unholder(item: T.List['ObjectHolder[_T]']) -> T.List[_T]: ...

@T.overload
def unholder(item: T.List[_T]) -> T.List[_T]: ...

@T.overload
def unholder(item: T.List[T.Union[_T, 'ObjectHolder[_T]']]) -> T.List[_T]: ...

def unholder(item):  # type: ignore  # TODO fix overload (somehow)
    """Get the held item of an object holder or list of object holders."""
    if isinstance(item, list):
        return [i.held_object if hasattr(i, 'held_object') else i for i in item]
    if hasattr(item, 'held_object'):
        return item.held_object
    return item


def listify(item: T.Any, flatten: bool = True) -> T.List[T.Any]:
    '''
    Returns a list with all args embedded in a list if they are not a list.
    This function preserves order.
    @flatten: Convert lists of lists to a flat list
    '''
    if not isinstance(item, list):
        return [item]
    result = []  # type: T.List[T.Any]
    for i in item:
        if flatten and isinstance(i, list):
            result += listify(i, flatten=True)
        else:
            result.append(i)
    return result


def extract_as_list(dict_object: T.Dict[_T, _U], key: _T, pop: bool = False) -> T.List[_U]:
    '''
    Extracts all values from given dict_object and listifies them.
    '''
    fetch = dict_object.get
    if pop:
        fetch = dict_object.pop
    # If there's only one key, we don't return a list with one element
    return listify(fetch(key, []), flatten=True)


def typeslistify(item: 'T.Union[_T, T.Sequence[_T]]',
                 types: 'T.Union[T.Type[_T], T.Tuple[T.Type[_T]]]') -> T.List[_T]:
    '''
    Ensure that type(@item) is one of @types or a
    list of items all of which are of type @types
    '''
    if isinstance(item, types):
        item = T.cast(T.List[_T], [item])
    if not isinstance(item, list):
        raise MesonException('Item must be a list or one of {!r}'.format(types))
    for i in item:
        if i is not None and not isinstance(i, types):
            raise MesonException('List item must be one of {!r}'.format(types))
    return item


def stringlistify(item: T.Union[T.Any, T.Sequence[T.Any]]) -> T.List[str]:
    return typeslistify(item, str)


def expand_arguments(args: T.Iterable[str]) -> T.Optional[T.List[str]]:
    expended_args = []  # type: T.List[str]
    for arg in args:
        if not arg.startswith('@'):
            expended_args.append(arg)
            continue

        args_file = arg[1:]
        try:
            with open(args_file) as f:
                extended_args = f.read().split()
            expended_args += extended_args
        except Exception as e:
            mlog.error('Expanding command line arguments:',  args_file, 'not found')
            mlog.exception(e)
            return None
    return expended_args


def partition(pred: T.Callable[[_T], object], iterable: T.Iterator[_T]) -> T.Tuple[T.Iterator[_T], T.Iterator[_T]]:
    """Use a predicate to partition entries into false entries and true
    entries.

    >>> x, y = partition(is_odd, range(10))
    >>> (list(x), list(y))
    ([0, 2, 4, 6, 8], [1, 3, 5, 7, 9])
    """
    t1, t2 = tee(iterable)
    return filterfalse(pred, t1), filter(pred, t2)


def Popen_safe(args: T.List[str], write: T.Optional[str] = None,
               stdout: T.Union[T.BinaryIO, int] = subprocess.PIPE,
               stderr: T.Union[T.BinaryIO, int] = subprocess.PIPE,
               **kwargs: T.Any) -> T.Tuple[subprocess.Popen, str, str]:
    import locale
    encoding = locale.getpreferredencoding()
    # Redirect stdin to DEVNULL otherwise the command run by us here might mess
    # up the console and ANSI colors will stop working on Windows.
    if 'stdin' not in kwargs:
        kwargs['stdin'] = subprocess.DEVNULL
    if sys.version_info < (3, 6) or not sys.stdout.encoding or encoding.upper() != 'UTF-8':
        p, o, e = Popen_safe_legacy(args, write=write, stdout=stdout, stderr=stderr, **kwargs)
    else:
        p = subprocess.Popen(args, universal_newlines=True, close_fds=False,
                             stdout=stdout, stderr=stderr, **kwargs)
        o, e = p.communicate(write)
    # Sometimes the command that we run will call another command which will be
    # without the above stdin workaround, so set the console mode again just in
    # case.
    mlog.setup_console()
    return p, o, e


def Popen_safe_legacy(args: T.List[str], write: T.Optional[str] = None,
                      stdout: T.Union[T.BinaryIO, int] = subprocess.PIPE,
                      stderr: T.Union[T.BinaryIO, int] = subprocess.PIPE,
                      **kwargs: T.Any) -> T.Tuple[subprocess.Popen, str, str]:
    p = subprocess.Popen(args, universal_newlines=False, close_fds=False,
                         stdout=stdout, stderr=stderr, **kwargs)
    input_ = None  # type: T.Optional[bytes]
    if write is not None:
        input_ = write.encode('utf-8')
    o, e = p.communicate(input_)
    if o is not None:
        if sys.stdout.encoding:
            o = o.decode(encoding=sys.stdout.encoding, errors='replace').replace('\r\n', '\n')
        else:
            o = o.decode(errors='replace').replace('\r\n', '\n')
    if e is not None:
        if sys.stderr.encoding:
            e = e.decode(encoding=sys.stderr.encoding, errors='replace').replace('\r\n', '\n')
        else:
            e = e.decode(errors='replace').replace('\r\n', '\n')
    return p, o, e


def iter_regexin_iter(regexiter: T.Iterable[str], initer: T.Iterable[str]) -> T.Optional[str]:
    '''
    Takes each regular expression in @regexiter and tries to search for it in
    every item in @initer. If there is a match, returns that match.
    Else returns False.
    '''
    for regex in regexiter:
        for ii in initer:
            if not isinstance(ii, str):
                continue
            match = re.search(regex, ii)
            if match:
                return match.group()
    return None


def _substitute_values_check_errors(command: T.List[str], values: T.Dict[str, str]) -> None:
    # Error checking
    inregex = ['@INPUT([0-9]+)?@', '@PLAINNAME@', '@BASENAME@']  # type: T.List[str]
    outregex = ['@OUTPUT([0-9]+)?@', '@OUTDIR@']                 # type: T.List[str]
    if '@INPUT@' not in values:
        # Error out if any input-derived templates are present in the command
        match = iter_regexin_iter(inregex, command)
        if match:
            m = 'Command cannot have {!r}, since no input files were specified'
            raise MesonException(m.format(match))
    else:
        if len(values['@INPUT@']) > 1:
            # Error out if @PLAINNAME@ or @BASENAME@ is present in the command
            match = iter_regexin_iter(inregex[1:], command)
            if match:
                raise MesonException('Command cannot have {!r} when there is '
                                     'more than one input file'.format(match))
        # Error out if an invalid @INPUTnn@ template was specified
        for each in command:
            if not isinstance(each, str):
                continue
            match2 = re.search(inregex[0], each)
            if match2 and match2.group() not in values:
                m = 'Command cannot have {!r} since there are only {!r} inputs'
                raise MesonException(m.format(match2.group(), len(values['@INPUT@'])))
    if '@OUTPUT@' not in values:
        # Error out if any output-derived templates are present in the command
        match = iter_regexin_iter(outregex, command)
        if match:
            m = 'Command cannot have {!r} since there are no outputs'
            raise MesonException(m.format(match))
    else:
        # Error out if an invalid @OUTPUTnn@ template was specified
        for each in command:
            if not isinstance(each, str):
                continue
            match2 = re.search(outregex[0], each)
            if match2 and match2.group() not in values:
                m = 'Command cannot have {!r} since there are only {!r} outputs'
                raise MesonException(m.format(match2.group(), len(values['@OUTPUT@'])))


def substitute_values(command: T.List[str], values: T.Dict[str, str]) -> T.List[str]:
    '''
    Substitute the template strings in the @values dict into the list of
    strings @command and return a new list. For a full list of the templates,
    see get_filenames_templates_dict()

    If multiple inputs/outputs are given in the @values dictionary, we
    substitute @INPUT@ and @OUTPUT@ only if they are the entire string, not
    just a part of it, and in that case we substitute *all* of them.
    '''
    # Error checking
    _substitute_values_check_errors(command, values)
    # Substitution
    outcmd = []  # type: T.List[str]
    rx_keys = [re.escape(key) for key in values if key not in ('@INPUT@', '@OUTPUT@')]
    value_rx = re.compile('|'.join(rx_keys)) if rx_keys else None
    for vv in command:
        if not isinstance(vv, str):
            outcmd.append(vv)
        elif '@INPUT@' in vv:
            inputs = values['@INPUT@']
            if vv == '@INPUT@':
                outcmd += inputs
            elif len(inputs) == 1:
                outcmd.append(vv.replace('@INPUT@', inputs[0]))
            else:
                raise MesonException("Command has '@INPUT@' as part of a "
                                     "string and more than one input file")
        elif '@OUTPUT@' in vv:
            outputs = values['@OUTPUT@']
            if vv == '@OUTPUT@':
                outcmd += outputs
            elif len(outputs) == 1:
                outcmd.append(vv.replace('@OUTPUT@', outputs[0]))
            else:
                raise MesonException("Command has '@OUTPUT@' as part of a "
                                     "string and more than one output file")
        # Append values that are exactly a template string.
        # This is faster than a string replace.
        elif vv in values:
            outcmd.append(values[vv])
        # Substitute everything else with replacement
        elif value_rx:
            outcmd.append(value_rx.sub(lambda m: values[m.group(0)], vv))
        else:
            outcmd.append(vv)
    return outcmd


def get_filenames_templates_dict(inputs: T.List[str], outputs: T.List[str]) -> T.Dict[str, T.Union[str, T.List[str]]]:
    '''
    Create a dictionary with template strings as keys and values as values for
    the following templates:

    @INPUT@  - the full path to one or more input files, from @inputs
    @OUTPUT@ - the full path to one or more output files, from @outputs
    @OUTDIR@ - the full path to the directory containing the output files

    If there is only one input file, the following keys are also created:

    @PLAINNAME@ - the filename of the input file
    @BASENAME@ - the filename of the input file with the extension removed

    If there is more than one input file, the following keys are also created:

    @INPUT0@, @INPUT1@, ... one for each input file

    If there is more than one output file, the following keys are also created:

    @OUTPUT0@, @OUTPUT1@, ... one for each output file
    '''
    values = {}  # type: T.Dict[str, T.Union[str, T.List[str]]]
    # Gather values derived from the input
    if inputs:
        # We want to substitute all the inputs.
        values['@INPUT@'] = inputs
        for (ii, vv) in enumerate(inputs):
            # Write out @INPUT0@, @INPUT1@, ...
            values['@INPUT{}@'.format(ii)] = vv
        if len(inputs) == 1:
            # Just one value, substitute @PLAINNAME@ and @BASENAME@
            values['@PLAINNAME@'] = plain = os.path.basename(inputs[0])
            values['@BASENAME@'] = os.path.splitext(plain)[0]
    if outputs:
        # Gather values derived from the outputs, similar to above.
        values['@OUTPUT@'] = outputs
        for (ii, vv) in enumerate(outputs):
            values['@OUTPUT{}@'.format(ii)] = vv
        # Outdir should be the same for all outputs
        values['@OUTDIR@'] = os.path.dirname(outputs[0])
        # Many external programs fail on empty arguments.
        if values['@OUTDIR@'] == '':
            values['@OUTDIR@'] = '.'
    return values


def _make_tree_writable(topdir: str) -> None:
    # Ensure all files and directories under topdir are writable
    # (and readable) by owner.
    for d, _, files in os.walk(topdir):
        os.chmod(d, os.stat(d).st_mode | stat.S_IWRITE | stat.S_IREAD)
        for fname in files:
            fpath = os.path.join(d, fname)
            if os.path.isfile(fpath):
                os.chmod(fpath, os.stat(fpath).st_mode | stat.S_IWRITE | stat.S_IREAD)


def windows_proof_rmtree(f: str) -> None:
    # On Windows if anyone is holding a file open you can't
    # delete it. As an example an anti virus scanner might
    # be scanning files you are trying to delete. The only
    # way to fix this is to try again and again.
    delays = [0.1, 0.1, 0.2, 0.2, 0.2, 0.5, 0.5, 1, 1, 1, 1, 2]
    # Start by making the tree wriable.
    _make_tree_writable(f)
    for d in delays:
        try:
            shutil.rmtree(f)
            return
        except FileNotFoundError:
            return
        except OSError:
            time.sleep(d)
    # Try one last time and throw if it fails.
    shutil.rmtree(f)


def windows_proof_rm(fpath: str) -> None:
    """Like windows_proof_rmtree, but for a single file."""
    if os.path.isfile(fpath):
        os.chmod(fpath, os.stat(fpath).st_mode | stat.S_IWRITE | stat.S_IREAD)
    delays = [0.1, 0.1, 0.2, 0.2, 0.2, 0.5, 0.5, 1, 1, 1, 1, 2]
    for d in delays:
        try:
            os.unlink(fpath)
            return
        except FileNotFoundError:
            return
        except OSError:
            time.sleep(d)
    os.unlink(fpath)


def detect_subprojects(spdir_name: str, current_dir: str = '',
                       result: T.Optional[T.Dict[str, T.List[str]]] = None) -> T.Optional[T.Dict[str, T.List[str]]]:
    if result is None:
        result = {}
    spdir = os.path.join(current_dir, spdir_name)
    if not os.path.exists(spdir):
        return result
    for trial in glob(os.path.join(spdir, '*')):
        basename = os.path.basename(trial)
        if trial == 'packagecache':
            continue
        append_this = True
        if os.path.isdir(trial):
            detect_subprojects(spdir_name, trial, result)
        elif trial.endswith('.wrap') and os.path.isfile(trial):
            basename = os.path.splitext(basename)[0]
        else:
            append_this = False
        if append_this:
            if basename in result:
                result[basename].append(trial)
            else:
                result[basename] = [trial]
    return result


def substring_is_in_list(substr: str, strlist: T.List[str]) -> bool:
    for s in strlist:
        if substr in s:
            return True
    return False


class OrderedSet(T.MutableSet[_T]):
    """A set that preserves the order in which items are added, by first
    insertion.
    """
    def __init__(self, iterable: T.Optional[T.Iterable[_T]] = None):
        # typing.OrderedDict is new in 3.7.2, so we can't use that, but we can
        # use MutableMapping, which is fine in this case.
        self.__container = collections.OrderedDict()  # type: T.MutableMapping[_T, None]
        if iterable:
            self.update(iterable)

    def __contains__(self, value: object) -> bool:
        return value in self.__container

    def __iter__(self) -> T.Iterator[_T]:
        return iter(self.__container.keys())

    def __len__(self) -> int:
        return len(self.__container)

    def __repr__(self) -> str:
        # Don't print 'OrderedSet("")' for an empty set.
        if self.__container:
            return 'OrderedSet("{}")'.format(
                '", "'.join(repr(e) for e in self.__container.keys()))
        return 'OrderedSet()'

    def __reversed__(self) -> T.Iterator[_T]:
        # Mypy is complaining that sets cant be reversed, which is true for
        # unordered sets, but this is an ordered, set so reverse() makes sense.
        return reversed(self.__container.keys())  # type: ignore

    def add(self, value: _T) -> None:
        self.__container[value] = None

    def discard(self, value: _T) -> None:
        if value in self.__container:
            del self.__container[value]

    def update(self, iterable: T.Iterable[_T]) -> None:
        for item in iterable:
            self.__container[item] = None

    def difference(self, set_: T.Union[T.Set[_T], 'OrderedSet[_T]']) -> 'OrderedSet[_T]':
        return type(self)(e for e in self if e not in set_)

class BuildDirLock:

    def __init__(self, builddir: str) -> None:
        self.lockfilename = os.path.join(builddir, 'meson-private/meson.lock')

    def __enter__(self) -> None:
        self.lockfile = open(self.lockfilename, 'w')
        try:
            if have_fcntl:
                fcntl.flock(self.lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
            elif have_msvcrt:
                msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
        except (BlockingIOError, PermissionError):
            self.lockfile.close()
            raise MesonException('Some other Meson process is already using this build directory. Exiting.')

    def __exit__(self, *args: T.Any) -> None:
        if have_fcntl:
            fcntl.flock(self.lockfile, fcntl.LOCK_UN)
        elif have_msvcrt:
            msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_UNLCK, 1)
        self.lockfile.close()

def relpath(path: str, start: str) -> str:
    # On Windows a relative path can't be evaluated for paths on two different
    # drives (i.e. c:\foo and f:\bar).  The only thing left to do is to use the
    # original absolute path.
    try:
        return os.path.relpath(path, start)
    except (TypeError, ValueError):
        return path

def path_is_in_root(path: Path, root: Path, resolve: bool = False) -> bool:
    # Check wheter a path is within the root directory root
    try:
        if resolve:
            path.resolve().relative_to(root.resolve())
        else:
            path.relative_to(root)
    except ValueError:
        return False
    return True

def relative_to_if_possible(path: Path, root: Path, resolve: bool = False) -> Path:
    try:
        if resolve:
            return path.resolve().relative_to(root.resolve())
        else:
            return path.relative_to(root)
    except ValueError:
        return path

class LibType(IntEnum):

    """Enumeration for library types."""

    SHARED = 0
    STATIC = 1
    PREFER_SHARED = 2
    PREFER_STATIC = 3


class ProgressBarFallback:  # lgtm [py/iter-returns-non-self]
    '''
    Fallback progress bar implementation when tqdm is not found

    Since this class is not an actual iterator, but only provides a minimal
    fallback, it is safe to ignore the 'Iterator does not return self from
    __iter__ method' warning.
    '''
    def __init__(self, iterable: T.Optional[T.Iterable[str]] = None, total: T.Optional[int] = None,
                 bar_type: T.Optional[str] = None, desc: T.Optional[str] = None):
        if iterable is not None:
            self.iterable = iter(iterable)
            return
        self.total = total
        self.done = 0
        self.printed_dots = 0
        if self.total and bar_type == 'download':
            print('Download size:', self.total)
        if desc:
            print('{}: '.format(desc), end='')

    # Pretend to be an iterator when called as one and don't print any
    # progress
    def __iter__(self) -> T.Iterator[str]:
        return self.iterable

    def __next__(self) -> str:
        return next(self.iterable)

    def print_dot(self) -> None:
        print('.', end='')
        sys.stdout.flush()
        self.printed_dots += 1

    def update(self, progress: int) -> None:
        self.done += progress
        if not self.total:
            # Just print one dot per call if we don't have a total length
            self.print_dot()
            return
        ratio = int(self.done / self.total * 10)
        while self.printed_dots < ratio:
            self.print_dot()

    def close(self) -> None:
        print('')

try:
    from tqdm import tqdm
except ImportError:
    # ideally we would use a typing.Protocol here, but it's part of typing_extensions until 3.8
    ProgressBar = ProgressBarFallback  # type: T.Union[T.Type[ProgressBarFallback], T.Type[ProgressBarTqdm]]
else:
    class ProgressBarTqdm(tqdm):
        def __init__(self, *args: T.Any, bar_type: T.Optional[str] = None, **kwargs: T.Any) -> None:
            if bar_type == 'download':
                kwargs.update({'unit': 'bytes', 'leave': True})
            else:
                kwargs.update({'leave': False})
            kwargs['ncols'] = 100
            super().__init__(*args, **kwargs)

    ProgressBar = ProgressBarTqdm


def get_wine_shortpath(winecmd: T.List[str], wine_paths: T.Sequence[str]) -> str:
    """Get A short version of @wine_paths to avoid reaching WINEPATH number
    of char limit.
    """

    wine_paths = list(OrderedSet(wine_paths))

    getShortPathScript = '%s.bat' % str(uuid.uuid4()).lower()[:5]
    with open(getShortPathScript, mode='w') as f:
        f.write("@ECHO OFF\nfor %%x in (%*) do (\n echo|set /p=;%~sx\n)\n")
        f.flush()
    try:
        with open(os.devnull, 'w') as stderr:
            wine_path = subprocess.check_output(
                winecmd +
                ['cmd', '/C', getShortPathScript] + wine_paths,
                stderr=stderr).decode('utf-8')
    except subprocess.CalledProcessError as e:
        print("Could not get short paths: %s" % e)
        wine_path = ';'.join(wine_paths)
    finally:
        os.remove(getShortPathScript)
    if len(wine_path) > 2048:
        raise MesonException(
            'WINEPATH size {} > 2048'
            ' this will cause random failure.'.format(
                len(wine_path)))

    return wine_path.strip(';')


def run_once(func: T.Callable[..., _T]) -> T.Callable[..., _T]:
    ret = []  # type: T.List[_T]

    @wraps(func)
    def wrapper(*args: T.Any, **kwargs: T.Any) -> _T:
        if ret:
            return ret[0]

        val = func(*args, **kwargs)
        ret.append(val)
        return val

    return wrapper


class OptionProxy(T.Generic[_T]):
    def __init__(self, value: _T):
        self.value = value


class OptionOverrideProxy(collections.abc.MutableMapping):

    '''Mimic an option list but transparently override selected option
    values.
    '''

    # TODO: the typing here could be made more explicit using a TypeDict from
    # python 3.8 or typing_extensions

    def __init__(self, overrides: T.Dict[str, T.Any], *options: 'OptionDictType'):
        self.overrides = overrides.copy()
        self.options = {}  # type: T.Dict[str, UserOption]
        for o in options:
            self.options.update(o)

    def __getitem__(self, key: str) -> T.Union['UserOption', OptionProxy]:
        if key in self.options:
            opt = self.options[key]
            if key in self.overrides:
                return OptionProxy(opt.validate_value(self.overrides[key]))
            return opt
        raise KeyError('Option not found', key)

    def __setitem__(self, key: str, value: T.Union['UserOption', OptionProxy]) -> None:
        self.overrides[key] = value.value

    def __delitem__(self, key: str) -> None:
        del self.overrides[key]

    def __iter__(self) -> T.Iterator[str]:
        return iter(self.options)

    def __len__(self) -> int:
        return len(self.options)

    def copy(self) -> 'OptionOverrideProxy':
        return OptionOverrideProxy(self.overrides.copy(), self.options.copy())