gecko-dev/build/moz.configure/toolchain.configure

# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
# vim: set filetype=python:
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

imply_option('--enable-release', mozilla_official)
imply_option('--enable-release', depends_if('MOZ_AUTOMATION')(lambda x: True))

js_option('--enable-release',
          default=milestone.is_release_or_beta,
          help='Build with more conservative, release engineering-oriented '
               'options. This may slow down builds.')


@depends('--enable-release')
def developer_options(value):
    if not value:
        return True


add_old_configure_assignment('DEVELOPER_OPTIONS', developer_options)
set_config('DEVELOPER_OPTIONS', developer_options)

# PGO
# ==============================================================
js_option(env='MOZ_PGO', help='Build with profile guided optimizations')

set_config('MOZ_PGO', depends('MOZ_PGO')(lambda x: bool(x)))
add_old_configure_assignment('MOZ_PGO', depends('MOZ_PGO')(lambda x: bool(x)))

# Code optimization
# ==============================================================

js_option('--enable-optimize',
          nargs='?',
          default=True,
          help='Enable optimizations via compiler flags')


@depends('--enable-optimize')
def moz_optimize(option):
    flags = None

    if len(option):
        val = '2'
        flags = option[0]
    elif option:
        val = '1'
    else:
        val = None

    return namespace(
        optimize=val,
        flags=flags,
    )


set_config('MOZ_OPTIMIZE', moz_optimize.optimize)
add_old_configure_assignment('MOZ_OPTIMIZE', moz_optimize.optimize)
add_old_configure_assignment('MOZ_CONFIGURE_OPTIMIZE_FLAGS', moz_optimize.flags)

# yasm detection
# ==============================================================
yasm = check_prog('YASM', ['yasm'], allow_missing=True)


@depends_if(yasm)
@checking('yasm version')
def yasm_version(yasm):
    version = check_cmd_output(
        yasm, '--version',
        onerror=lambda: die('Failed to get yasm version.')
    ).splitlines()[0].split()[1]
    return Version(version)


@depends_if(yasm_version)
def yasm_major_version(yasm_version):
    return str(yasm_version.major)


@depends_if(yasm_version)
def yasm_minor_version(yasm_version):
    return str(yasm_version.minor)


set_config('YASM_MAJOR_VERSION', yasm_major_version)
set_config('YASM_MINOR_VERSION', yasm_minor_version)
# Until we move all the yasm consumers out of old-configure.
# bug 1257904
add_old_configure_assignment('_YASM_MAJOR_VERSION',
                             yasm_version.major)
add_old_configure_assignment('_YASM_MINOR_VERSION',
                             yasm_version.minor)


@depends(yasm, target)
def yasm_asflags(yasm, target):
    if yasm:
        asflags = {
            ('OSX', 'x86'): ['-f', 'macho32'],
            ('OSX', 'x86_64'): ['-f', 'macho64'],
            ('WINNT', 'x86'): ['-f', 'win32'],
            ('WINNT', 'x86_64'): ['-f', 'x64'],
        }.get((target.os, target.cpu), None)
        if asflags is None:
            # We're assuming every x86 platform we support that's
            # not Windows or Mac is ELF.
            if target.cpu == 'x86':
                asflags = ['-f', 'elf32']
            elif target.cpu == 'x86_64':
                asflags = ['-f', 'elf64']
        if asflags:
            asflags += ['-rnasm', '-pnasm']
        return asflags


set_config('YASM_ASFLAGS', yasm_asflags)


@depends(yasm_asflags)
def have_yasm(value):
    if value:
        return True


set_config('HAVE_YASM', have_yasm)
# Until the YASM variable is not necessary in old-configure.
add_old_configure_assignment('YASM', have_yasm)

# Android NDK
# ==============================================================


@depends('--disable-compile-environment', build_project, '--help')
def compiling_android(compile_env, build_project, _):
    return compile_env and build_project in ('mobile/android', 'js')


include('android-ndk.configure', when=compiling_android)

# MacOS deployment target version
# ==============================================================
# This needs to happen before any compilation test is done.

option('--enable-macos-target', env='MACOSX_DEPLOYMENT_TARGET', nargs=1,
       default='10.9', help='Set the minimum MacOS version needed at runtime')


@depends('--enable-macos-target', target)
@imports(_from='os', _import='environ')
def macos_target(value, target):
    if value and target.os == 'OSX':
        # Ensure every compiler process we spawn uses this value.
        environ['MACOSX_DEPLOYMENT_TARGET'] = value[0]
        return value[0]
    if value and value.origin != 'default':
        die('--enable-macos-target cannot be used when targeting %s',
            target.os)


set_config('MACOSX_DEPLOYMENT_TARGET', macos_target)
add_old_configure_assignment('MACOSX_DEPLOYMENT_TARGET', macos_target)

# Xcode state
# ===========

js_option('--disable-xcode-checks',
          help='Do not check that Xcode is installed and properly configured')


@depends(host, '--disable-xcode-checks')
def xcode_path(host, xcode_checks):
    if host.kernel != 'Darwin' or not xcode_checks:
        return

    # xcode-select -p prints the path to the installed Xcode. It
    # should exit 0 and return non-empty result if Xcode is installed.

    def bad_xcode_select():
        die('Could not find installed Xcode; install Xcode from the App '
            'Store, run it once to perform initial configuration, and then '
            'try again; in the rare case you wish to build without Xcode '
            'installed, add the --disable-xcode-checks configure flag')

    xcode_path = check_cmd_output('xcode-select', '--print-path',
                                  onerror=bad_xcode_select).strip()

    if not xcode_path:
        bad_xcode_select()

    # Now look for the Command Line Tools.
    def no_cltools():
        die('Could not find installed Xcode Command Line Tools; '
            'run `xcode-select --install` and follow the instructions '
            'to install them then try again; if you wish to build without '
            'Xcode Command Line Tools installed, '
            'add the --disable-xcode-checks configure flag')

    check_cmd_output('pkgutil', '--pkg-info',
                     'com.apple.pkg.CLTools_Executables',
                     onerror=no_cltools)

    return xcode_path


set_config('XCODE_PATH', xcode_path)


# Compiler wrappers
# ==============================================================
# Normally, we'd use js_option and automatically have those variables
# propagated to js/src, but things are complicated by possible additional
# wrappers in CC/CXX, and by other subconfigures that do not handle those
# options and do need CC/CXX altered.
option('--with-compiler-wrapper', env='COMPILER_WRAPPER', nargs=1,
       help='Enable compiling with wrappers such as distcc and ccache')

option('--with-ccache', env='CCACHE', nargs='?',
       help='Enable compiling with ccache')


@depends_if('--with-ccache')
def ccache(value):
    if len(value):
        return value
    # If --with-ccache was given without an explicit value, we default to
    # 'ccache'.
    return 'ccache'


ccache = check_prog('CCACHE', progs=(), input=ccache)

# Distinguish ccache from sccache.


@depends_if(ccache)
def ccache_is_sccache(ccache):
    return check_cmd_output(ccache, '--version').startswith('sccache')


@depends(ccache, ccache_is_sccache)
def using_ccache(ccache, ccache_is_sccache):
    return ccache and not ccache_is_sccache


@depends_if(ccache, ccache_is_sccache)
def using_sccache(ccache, ccache_is_sccache):
    return ccache and ccache_is_sccache


set_config('MOZ_USING_CCACHE', using_ccache)
set_config('MOZ_USING_SCCACHE', using_sccache)

option(env='SCCACHE_VERBOSE_STATS',
       help='Print verbose sccache stats after build')


@depends(using_sccache, 'SCCACHE_VERBOSE_STATS')
def sccache_verbose_stats(using_sccache, verbose_stats):
    return using_sccache and bool(verbose_stats)


set_config('SCCACHE_VERBOSE_STATS', sccache_verbose_stats)


@depends('--with-compiler-wrapper', ccache)
@imports(_from='mozbuild.shellutil', _import='split', _as='shell_split')
def compiler_wrapper(wrapper, ccache):
    if wrapper:
        raw_wrapper = wrapper[0]
        wrapper = shell_split(raw_wrapper)
        wrapper_program = find_program(wrapper[0])
        if not wrapper_program:
            die('Cannot find `%s` from the given compiler wrapper `%s`',
                wrapper[0], raw_wrapper)
        wrapper[0] = wrapper_program

    if ccache:
        if wrapper:
            return tuple([ccache] + wrapper)
        else:
            return (ccache,)
    elif wrapper:
        return tuple(wrapper)


add_old_configure_assignment('COMPILER_WRAPPER', compiler_wrapper)


@depends_if(compiler_wrapper)
def using_compiler_wrapper(compiler_wrapper):
    return True


set_config('MOZ_USING_COMPILER_WRAPPER', using_compiler_wrapper)


# GC rooting and hazard analysis.
# ==============================================================
option(env='MOZ_HAZARD', help='Build for the GC rooting hazard analysis')


@depends('MOZ_HAZARD')
def hazard_analysis(value):
    if value:
        return True


set_config('MOZ_HAZARD', hazard_analysis)


# Cross-compilation related things.
# ==============================================================
js_option('--with-toolchain-prefix', env='TOOLCHAIN_PREFIX', nargs=1,
          help='Prefix for the target toolchain')


@depends('--with-toolchain-prefix', target, cross_compiling)
def toolchain_prefix(value, target, cross_compiling):
    if value:
        return tuple(value)
    if cross_compiling:
        return ('%s-' % target.toolchain, '%s-' % target.alias)


@depends(toolchain_prefix, target)
def first_toolchain_prefix(toolchain_prefix, target):
    # Pass TOOLCHAIN_PREFIX down to the build system if it was given from the
    # command line/environment (in which case there's only one value in the tuple),
    # or when cross-compiling for Android.
    if toolchain_prefix and (target.os == 'Android' or len(toolchain_prefix) == 1):
        return toolchain_prefix[0]


set_config('TOOLCHAIN_PREFIX', first_toolchain_prefix)
add_old_configure_assignment('TOOLCHAIN_PREFIX', first_toolchain_prefix)


# Compilers
# ==============================================================
include('compilers-util.configure')


def try_preprocess(compiler, language, source):
    return try_invoke_compiler(compiler, language, source, ['-E'])


@imports(_from='mozbuild.configure.constants', _import='CompilerType')
@imports(_from='mozbuild.configure.constants',
         _import='CPU_preprocessor_checks')
@imports(_from='mozbuild.configure.constants',
         _import='kernel_preprocessor_checks')
@imports(_from='textwrap', _import='dedent')
def get_compiler_info(compiler, language):
    '''Returns information about the given `compiler` (command line in the
    form of a list or tuple), in the given `language`.

    The returned information includes:
    - the compiler type (msvc, clang-cl, clang or gcc)
    - the compiler version
    - the compiler supported language
    - the compiler supported language version
    '''
    # Note: MSVC doesn't expose __STDC_VERSION__. It does expose __STDC__,
    # but only when given the -Za option, which disables compiler
    # extensions.
    # Note: We'd normally do a version check for clang, but versions of clang
    # in Xcode have a completely different versioning scheme despite exposing
    # the version with the same defines.
    # So instead, we make things such that the version is missing when the
    # clang used is below the minimum supported version (currently clang 3.6).
    # We then only include the version information when the C++ compiler
    # matches the feature check, so that an unsupported version of clang would
    # have no version number.
    check = dedent('''\
        #if defined(_MSC_VER)
        #if defined(__clang__)
        %COMPILER "clang-cl"
        %VERSION _MSC_FULL_VER
        #else
        %COMPILER "msvc"
        %VERSION _MSC_FULL_VER
        #endif
        #elif defined(__clang__)
        %COMPILER "clang"
        #  if !__cplusplus || __has_feature(cxx_alignof)
        %VERSION __clang_major__.__clang_minor__.__clang_patchlevel__
        #  endif
        #elif defined(__GNUC__)
        %COMPILER "gcc"
        %VERSION __GNUC__.__GNUC_MINOR__.__GNUC_PATCHLEVEL__
        #endif

        #if __cplusplus
        %cplusplus __cplusplus
        #elif __STDC_VERSION__
        %STDC_VERSION __STDC_VERSION__
        #elif __STDC__
        %STDC_VERSION 198900L
        #endif
    ''')

    # While we're doing some preprocessing, we might as well do some more
    # preprocessor-based tests at the same time, to check the toolchain
    # matches what we want.
    for name, preprocessor_checks in (
        ('CPU', CPU_preprocessor_checks),
        ('KERNEL', kernel_preprocessor_checks),
    ):
        for n, (value, condition) in enumerate(preprocessor_checks.iteritems()):
            check += dedent('''\
                #%(if)s %(condition)s
                %%%(name)s "%(value)s"
            ''' % {
                'if': 'elif' if n else 'if',
                'condition': condition,
                'name': name,
                'value': value,
            })
        check += '#endif\n'

    # Also check for endianness. The advantage of living in modern times is
    # that all the modern compilers we support now have __BYTE_ORDER__ defined
    # by the preprocessor, except MSVC, which only supports little endian.
    check += dedent('''\
        #if _MSC_VER || __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
        %ENDIANNESS "little"
        #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
        %ENDIANNESS "big"
        #endif
    ''')

    result = try_preprocess(compiler, language, check)

    if not result:
        raise FatalCheckError(
            'Unknown compiler or compiler not supported.')

    # Metadata emitted by preprocessors such as GCC with LANG=ja_JP.utf-8 may
    # have non-ASCII characters. Treat the output as bytearray.
    data = {}
    for line in result.splitlines():
        if line.startswith(b'%'):
            k, _, v = line.partition(' ')
            k = k.lstrip('%')
            data[k] = v.replace(' ', '').lstrip('"').rstrip('"')
            log.debug('%s = %s', k, data[k])

    try:
        type = CompilerType(data['COMPILER'])
    except Exception:
        raise FatalCheckError(
            'Unknown compiler or compiler not supported.')

    cplusplus = int(data.get('cplusplus', '0L').rstrip('L'))
    stdc_version = int(data.get('STDC_VERSION', '0L').rstrip('L'))

    version = data.get('VERSION')
    if version and type in ('msvc', 'clang-cl'):
        msc_ver = version
        version = msc_ver[0:2]
        if len(msc_ver) > 2:
            version += '.' + msc_ver[2:4]
        if len(msc_ver) > 4:
            version += '.' + msc_ver[4:]

    if version:
        version = Version(version)

    return namespace(
        type=type,
        version=version,
        cpu=data.get('CPU'),
        kernel=data.get('KERNEL'),
        endianness=data.get('ENDIANNESS'),
        language='C++' if cplusplus else 'C',
        language_version=cplusplus if cplusplus else stdc_version,
    )


@imports(_from='mozbuild.shellutil', _import='quote')
def check_compiler(compiler, language, target):
    info = get_compiler_info(compiler, language)

    flags = []

    def append_flag(flag):
        if flag not in flags:
            if info.type == 'clang-cl':
                flags.append('-Xclang')
            flags.append(flag)

    # Check language standards
    # --------------------------------------------------------------------
    if language != info.language:
        raise FatalCheckError(
            '`%s` is not a %s compiler.' % (quote(*compiler), language))

    # Note: We do a strict version check because there sometimes are backwards
    # incompatible changes in the standard, and not all code that compiles as
    # C99 compiles as e.g. C11 (as of writing, this is true of libnestegg, for
    # example)
    if info.language == 'C' and info.language_version != 199901:
        if info.type in ('clang-cl', 'clang', 'gcc'):
            append_flag('-std=gnu99')

    # Note: MSVC, while supporting C++14, still reports 199711L for __cplusplus.
    # Note: this is a strict version check because we used to always add
    # -std=gnu++14.
    cxx14_version = 201402
    if info.language == 'C++':
        if info.type == 'clang' and info.language_version != cxx14_version:
            append_flag('-std=gnu++14')
        # MSVC headers include C++14 features, but don't guard them
        # with appropriate checks.
        elif info.type == 'clang-cl' and info.language_version != cxx14_version:
            append_flag('-std=c++14')

    # We force clang-cl to emulate Visual C++ 2017 version 15.6.0
    msvc_version = '19.13.26128'
    if info.type == 'clang-cl' and info.version != msvc_version:
        # This flag is a direct clang-cl flag that doesn't need -Xclang,
        # add it directly.
        flags.append('-fms-compatibility-version=%s' % msvc_version)

    # Check compiler target
    # --------------------------------------------------------------------
    if not info.cpu or info.cpu != target.cpu:
        if info.type == 'clang':
            append_flag('--target=%s' % target.toolchain)
        elif info.type == 'clang-cl':
            # Ideally this would share the 'clang' branch above, but on Windows
            # the --target needs additional data like ms-compatibility-version.
            if (info.cpu, target.cpu) == ('x86_64', 'x86'):
                # -m32 does not use -Xclang, so add it directly.
                flags.append('-m32')
        elif info.type == 'gcc':
            same_arch_different_bits = (
                ('x86', 'x86_64'),
                ('ppc', 'ppc64'),
                ('sparc', 'sparc64'),
            )
            if (target.cpu, info.cpu) in same_arch_different_bits:
                append_flag('-m32')
            elif (info.cpu, target.cpu) in same_arch_different_bits:
                append_flag('-m64')

    if not info.kernel or info.kernel != target.kernel:
        if info.type == 'clang':
            append_flag('--target=%s' % target.toolchain)

    if not info.endianness or info.endianness != target.endianness:
        if info.type == 'clang':
            append_flag('--target=%s' % target.toolchain)

    return namespace(
        type=info.type,
        version=info.version,
        target_cpu=info.cpu,
        target_kernel=info.kernel,
        target_endianness=info.endianness,
        flags=flags,
    )


@imports(_from='__builtin__', _import='open')
@imports('json')
@imports('subprocess')
@imports('sys')
def get_vc_paths(topsrcdir):
    def vswhere(args):
        encoding = 'mbcs' if sys.platform == 'win32' else 'utf-8'
        return json.loads(
            subprocess.check_output([
                os.path.join(topsrcdir, 'build/win32/vswhere.exe'),
                '-format',
                'json'
            ] + args).decode(encoding, 'replace'))

    for install in vswhere(['-requires', 'Microsoft.VisualStudio.Component.VC.Tools.x86.x64']):
        path = install['installationPath']
        tools_version = open(os.path.join(
            path, r'VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt'), 'rb').read().strip()
        tools_path = os.path.join(
            path, r'VC\Tools\MSVC', tools_version, r'bin\HostX64')
        yield (Version(install['installationVersion']), {
            'x64': [os.path.join(tools_path, 'x64')],
            # The x64->x86 cross toolchain requires DLLs from the native x64 toolchain.
            'x86': [os.path.join(tools_path, 'x86'), os.path.join(tools_path, 'x64')],
        })


js_option('--with-visual-studio-version', nargs=1,
          choices=('2017',),
          help='Select a specific Visual Studio version to use')


@depends('--with-visual-studio-version')
def vs_major_version(value):
    if value:
        return {'2017': 15}[value[0]]


@depends(host, target, vs_major_version, check_build_environment, '--with-visual-studio-version')
@imports(_from='__builtin__', _import='sorted')
@imports(_from='operator', _import='itemgetter')
@imports('platform')
def vc_compiler_path(host, target, vs_major_version, env, vs_release_name):
    if host.kernel != 'WINNT':
        return
    vc_target = {
        'x86': 'x86',
        'x86_64': 'x64',
        'arm': 'arm',
    }.get(target.cpu)
    if vc_target is None:
        return

    all_versions = sorted(get_vc_paths(env.topsrcdir), key=itemgetter(0))
    if not all_versions:
        return
    if vs_major_version:
        versions = [d for (v, d) in all_versions if v.major ==
                    vs_major_version]
        if not versions:
            die('Visual Studio %s could not be found!' % vs_release_name)
        data = versions[0]
    else:
        # Choose the newest version.
        data = all_versions[-1][1]
    paths = data.get(vc_target)
    if not paths:
        return
    return paths


@depends(vc_compiler_path)
@imports('os')
@imports(_from='os', _import='environ')
def toolchain_search_path(vc_compiler_path):
    result = [environ.get('PATH')]

    if vc_compiler_path:
        result.extend(vc_compiler_path)

    # Also add in the location to which `mach bootstrap` or
    # `mach artifact toolchain` installs clang.
    mozbuild_state_dir = environ.get('MOZBUILD_STATE_PATH',
                                     os.path.expanduser(os.path.join('~', '.mozbuild')))
    bootstrap_clang_path = os.path.join(mozbuild_state_dir, 'clang', 'bin')
    result.append(bootstrap_clang_path)

    if vc_compiler_path:
        # We're going to alter PATH for good in windows.configure, but we also
        # need to do it for the valid_compiler() check below. This is only needed
        # on Windows, where MSVC needs PATH set to find dlls.
        environ['PATH'] = os.pathsep.join(result)

    return result


@template
def default_c_compilers(host_or_target):
    '''Template defining the set of default C compilers for the host and
    target platforms.
    `host_or_target` is either `host` or `target` (the @depends functions
    from init.configure.
    '''
    assert host_or_target in (host, target)

    @depends(host_or_target, target, toolchain_prefix, android_clang_compiler,
             developer_options)
    def default_c_compilers(host_or_target, target, toolchain_prefix,
                            android_clang_compiler, developer_options):
        gcc = ('gcc',)
        if toolchain_prefix and host_or_target is target:
            gcc = tuple('%sgcc' % p for p in toolchain_prefix) + gcc
        # Android sets toolchain_prefix and android_clang_compiler, but
        # we want the latter to take precedence, because the latter can
        # point at clang, which is what we want to use.
        if android_clang_compiler and host_or_target is target:
            return (android_clang_compiler,) + gcc

        if host_or_target.kernel == 'WINNT':
            return ('cl', 'clang-cl') + gcc + ('clang',)
        if host_or_target.kernel == 'Darwin':
            return ('clang',)
        if developer_options:
            return ('clang',) + gcc
        return gcc + ('clang',)

    return default_c_compilers


@template
def default_cxx_compilers(c_compiler):
    '''Template defining the set of default C++ compilers for the host and
    target platforms.
    `c_compiler` is the @depends function returning a Compiler instance for
    the desired platform.

    Because the build system expects the C and C++ compilers to be from the
    same compiler suite, we derive the default C++ compilers from the C
    compiler that was found if none was provided.
    '''

    @depends(c_compiler)
    def default_cxx_compilers(c_compiler):
        dir = os.path.dirname(c_compiler.compiler)
        file = os.path.basename(c_compiler.compiler)

        if c_compiler.type == 'gcc':
            return (os.path.join(dir, file.replace('gcc', 'g++')),)

        if c_compiler.type == 'clang':
            return (os.path.join(dir, file.replace('clang', 'clang++')),)

        return (c_compiler.compiler,)

    return default_cxx_compilers


@template
def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
             other_c_compiler=None):
    '''Template handling the generic base checks for the compiler for the
    given `language` on the given platform (`host_or_target`).
    `host_or_target` is either `host` or `target` (the @depends functions
    from init.configure.
    When the language is 'C++', `c_compiler` is the result of the `compiler`
    template for the language 'C' for the same `host_or_target`.
    When `host_or_target` is `host`, `other_compiler` is the result of the
    `compiler` template for the same `language` for `target`.
    When `host_or_target` is `host` and the language is 'C++',
    `other_c_compiler` is the result of the `compiler` template for the
    language 'C' for `target`.
    '''
    assert host_or_target in (host, target)
    assert language in ('C', 'C++')
    assert language == 'C' or c_compiler is not None
    assert host_or_target == target or other_compiler is not None
    assert language == 'C' or host_or_target == target or \
        other_c_compiler is not None

    host_or_target_str = {
        host: 'host',
        target: 'target',
    }[host_or_target]

    var = {
        ('C', target): 'CC',
        ('C++', target): 'CXX',
        ('C', host): 'HOST_CC',
        ('C++', host): 'HOST_CXX',
    }[language, host_or_target]

    default_compilers = {
        'C': lambda: default_c_compilers(host_or_target),
        'C++': lambda: default_cxx_compilers(c_compiler),
    }[language]()

    what = 'the %s %s compiler' % (host_or_target_str, language)

    option(env=var, nargs=1, help='Path to %s' % what)

    # Handle the compiler given by the user through one of the CC/CXX/HOST_CC/
    # HOST_CXX variables.
    @depends_if(var)
    @imports(_from='itertools', _import='takewhile')
    @imports(_from='mozbuild.shellutil', _import='split', _as='shell_split')
    def provided_compiler(cmd):
        # Historically, the compiler variables have contained more than the
        # path to the compiler itself. So for backwards compatibility, try to
        # find what is what in there, assuming the first dash-prefixed item is
        # a compiler option, the item before that is the compiler, and anything
        # before that is a compiler wrapper.
        cmd = shell_split(cmd[0])

        without_flags = list(takewhile(lambda x: not x.startswith('-'), cmd))

        return namespace(
            wrapper=without_flags[:-1],
            compiler=without_flags[-1],
            flags=cmd[len(without_flags):],
        )

    # Derive the host compiler from the corresponding target compiler when no
    # explicit compiler was given and we're not cross compiling. For the C++
    # compiler, though, prefer to derive from the host C compiler when it
    # doesn't match the target C compiler.
    # As a special case, since clang supports all kinds of targets in the same
    # executable, when cross compiling with clang, default to the same compiler
    # as the target compiler, resetting flags.  However, Android NDK clangs do
    # not function as host compilers -- they're target compilers only -- so
    # don't use clang target as host if the target OS is Android.
    if host_or_target == host:
        if other_c_compiler is not None:
            args = (c_compiler, other_c_compiler)
        else:
            args = ()

        @depends(provided_compiler, other_compiler, cross_compiling,
                 target, *args)
        def provided_compiler(value, other_compiler, cross_compiling,
                              target, *args):
            if value:
                return value
            c_compiler, other_c_compiler = args if args else (None, None)
            if not cross_compiling and c_compiler == other_c_compiler:
                return other_compiler
            if cross_compiling and other_compiler.type == 'clang' and \
                    target.os != 'Android':
                return namespace(**{
                    k: [] if k == 'flags' else v
                    for k, v in other_compiler.__dict__.iteritems()
                })

    # Normally, we'd use `var` instead of `_var`, but the interaction with
    # old-configure complicates things, and for now, we a) can't take the plain
    # result from check_prog as CC/CXX/HOST_CC/HOST_CXX and b) have to let
    # old-configure AC_SUBST it (because it's autoconf doing it, not us)
    compiler = check_prog('_%s' % var, what=what, progs=default_compilers,
                          input=provided_compiler.compiler,
                          paths=toolchain_search_path)

    @depends(compiler, provided_compiler, compiler_wrapper, host_or_target)
    @checking('whether %s can be used' % what, lambda x: bool(x))
    @imports(_from='mozbuild.shellutil', _import='quote')
    def valid_compiler(compiler, provided_compiler, compiler_wrapper,
                       host_or_target):
        wrapper = list(compiler_wrapper or ())
        if provided_compiler:
            provided_wrapper = list(provided_compiler.wrapper)
            # When doing a subconfigure, the compiler is set by old-configure
            # and it contains the wrappers from --with-compiler-wrapper and
            # --with-ccache.
            if provided_wrapper[:len(wrapper)] == wrapper:
                provided_wrapper = provided_wrapper[len(wrapper):]
            wrapper.extend(provided_wrapper)
            flags = provided_compiler.flags
        else:
            flags = []

        # Ideally, we'd always use the absolute path, but unfortunately, on
        # Windows, the compiler is very often in a directory containing spaces.
        # Unfortunately, due to the way autoconf does its compiler tests with
        # eval, that doesn't work out. So in that case, check that the
        # compiler can still be found in $PATH, and use the file name instead
        # of the full path.
        if quote(compiler) != compiler:
            full_path = os.path.abspath(compiler)
            compiler = os.path.basename(compiler)
            found_compiler = find_program(compiler)
            if not found_compiler:
                die('%s is not in your $PATH'
                    % quote(os.path.dirname(full_path)))
            if os.path.normcase(find_program(compiler)) != os.path.normcase(
                    full_path):
                die('Found `%s` before `%s` in your $PATH. '
                    'Please reorder your $PATH.',
                    quote(os.path.dirname(found_compiler)),
                    quote(os.path.dirname(full_path)))

        info = check_compiler(wrapper + [compiler] + flags, language,
                              host_or_target)

        # Check that the additional flags we got are enough to not require any
        # more flags. If we get an exception, just ignore it; it's liable to be
        # invalid command-line flags, which means the compiler we're checking
        # doesn't support those command-line flags and will fail one or more of
        # the checks below.
        try:
            if info.flags:
                flags += info.flags
                info = check_compiler(wrapper + [compiler] + flags, language,
                                      host_or_target)
        except FatalCheckError:
            pass

        if not info.target_cpu or info.target_cpu != host_or_target.cpu:
            raise FatalCheckError(
                '%s %s compiler target CPU (%s) does not match --%s CPU (%s)'
                % (host_or_target_str.capitalize(), language,
                   info.target_cpu or 'unknown', host_or_target_str,
                   host_or_target.raw_cpu))

        if not info.target_kernel or (info.target_kernel !=
                                      host_or_target.kernel):
            raise FatalCheckError(
                '%s %s compiler target kernel (%s) does not match --%s kernel (%s)'
                % (host_or_target_str.capitalize(), language,
                   info.target_kernel or 'unknown', host_or_target_str,
                   host_or_target.kernel))

        if not info.target_endianness or (info.target_endianness !=
                                          host_or_target.endianness):
            raise FatalCheckError(
                '%s %s compiler target endianness (%s) does not match --%s '
                'endianness (%s)'
                % (host_or_target_str.capitalize(), language,
                   info.target_endianness or 'unknown', host_or_target_str,
                   host_or_target.endianness))

        # Compiler version checks
        # ===================================================
        # Check the compiler version here instead of in `compiler_version` so
        # that the `checking` message doesn't pretend the compiler can be used
        # to then bail out one line later.
        if info.type == 'gcc':
            if host_or_target.os == 'Android':
                raise FatalCheckError('GCC is not supported on Android.\n'
                                      'Please use clang from the Android NDK instead.')
            if info.version < '6.1.0':
                raise FatalCheckError(
                    'Only GCC 6.1 or newer is supported (found version %s).'
                    % info.version)

        # If you want to bump the version check here search for
        # cxx_alignof above, and see the associated comment.
        if info.type == 'clang' and not info.version:
            raise FatalCheckError(
                'Only clang/llvm 3.6 or newer is supported.')

        if info.type == 'msvc':
            if info.version < '19.13.26128':
                raise FatalCheckError(
                    'This version (%s) of the MSVC compiler is not '
                    'supported.\n'
                    'You must install Visual C++ 2017 Update 6 in '
                    'order to build.\n'
                    'See https://developer.mozilla.org/en/'
                    'Windows_Build_Prerequisites' % info.version)

            # MSVC version 15.7 and the previews for 15.8, at least,
            # can't build Firefox.
            if info.version >= '19.14.0':
                raise FatalCheckError(
                    'This version (%s) of the MSVC compiler is not '
                    'supported due to compiler bugs.\n'
                    'You must install Visual C++ 2017 Update 6 in '
                    'order to build.\n'
                    'See https://developer.mozilla.org/en/'
                    'Windows_Build_Prerequisites' % info.version)

        if info.flags:
            raise FatalCheckError(
                'Unknown compiler or compiler not supported.')

        return namespace(
            wrapper=wrapper,
            compiler=compiler,
            flags=flags,
            type=info.type,
            version=info.version,
            language=language,
        )

    @depends(valid_compiler)
    @checking('%s version' % what)
    def compiler_version(compiler):
        return compiler.version

    if language == 'C++':
        @depends(valid_compiler, c_compiler)
        def valid_compiler(compiler, c_compiler):
            if compiler.type != c_compiler.type:
                die('The %s C compiler is %s, while the %s C++ compiler is '
                    '%s. Need to use the same compiler suite.',
                    host_or_target_str, c_compiler.type,
                    host_or_target_str, compiler.type)

            if compiler.version != c_compiler.version:
                die('The %s C compiler is version %s, while the %s C++ '
                    'compiler is version %s. Need to use the same compiler '
                    'version.',
                    host_or_target_str, c_compiler.version,
                    host_or_target_str, compiler.version)
            return compiler

    # Set CC/CXX/HOST_CC/HOST_CXX for old-configure, which needs the wrapper
    # and the flags that were part of the user input for those variables to
    # be provided.
    add_old_configure_assignment(var, depends_if(valid_compiler)(
        lambda x: list(x.wrapper) + [x.compiler] + list(x.flags)))

    # Set CC_TYPE/CC_VERSION/HOST_CC_TYPE/HOST_CC_VERSION to allow
    # old-configure to do some of its still existing checks.
    if language == 'C':
        set_config(
            '%s_TYPE' % var, valid_compiler.type)
        add_old_configure_assignment(
            '%s_TYPE' % var, valid_compiler.type)
        add_old_configure_assignment(
            '%s_VERSION' % var, valid_compiler.version)

    valid_compiler = compiler_class(valid_compiler, host_or_target)

    def compiler_error():
        raise FatalCheckError('Failed compiling a simple %s source with %s'
                              % (language, what))

    valid_compiler.try_compile(check_msg='%s works' % what,
                               onerror=compiler_error)

    # Set CPP/CXXCPP for both the build system and old-configure. We don't
    # need to check this works for preprocessing, because we already relied
    # on $CC -E/$CXX -E doing preprocessing work to validate the compiler
    # in the first place.
    if host_or_target == target:
        pp_var = {
            'C': 'CPP',
            'C++': 'CXXCPP',
        }[language]

        preprocessor = depends_if(valid_compiler)(
            lambda x: list(x.wrapper) + [x.compiler, '-E'] + list(x.flags))

        set_config(pp_var, preprocessor)
        add_old_configure_assignment(pp_var, preprocessor)

    if language == 'C':
        linker_var = {
            target: 'LD',
            host: 'HOST_LD',
        }[host_or_target]

        @deprecated_option(env=linker_var, nargs=1)
        def linker(value):
            if value:
                return value[0]

        @depends(valid_compiler, linker)
        def unused_linker(compiler, linker):
            if linker and compiler.type != 'msvc':
                log.warning('The value of %s is not used by this build system.'
                            % linker_var)

        if host_or_target == target:
            @depends(valid_compiler)
            def is_msvc(compiler):
                return compiler.type == 'msvc'

            imply_option('LINKER', linker, reason='LD', when=is_msvc)

    return valid_compiler


c_compiler = compiler('C', target)
cxx_compiler = compiler('C++', target, c_compiler=c_compiler)
host_c_compiler = compiler('C', host, other_compiler=c_compiler)
host_cxx_compiler = compiler('C++', host, c_compiler=host_c_compiler,
                             other_compiler=cxx_compiler,
                             other_c_compiler=c_compiler)

# Generic compiler-based conditions.
non_msvc_compiler = depends(c_compiler)(lambda info: info.type != 'msvc')
building_with_gcc = depends(c_compiler)(lambda info: info.type == 'gcc')


@depends(c_compiler)
def msvs_version(info):
    # clang-cl emulates the same version scheme as cl. And MSVS_VERSION needs to
    # be set for GYP on Windows.
    if info.type in ('clang-cl', 'msvc'):
        if info.version >= '19.10':
            return '2017'

    return ''


set_config('MSVS_VERSION', msvs_version)

include('compile-checks.configure')


@depends(have_64_bit,
         try_compile(body='static_assert(sizeof(void *) == 8, "")',
                     check_msg='for 64-bit OS'))
def check_have_64_bit(have_64_bit, compiler_have_64_bit):
    if have_64_bit != compiler_have_64_bit:
        configure_error('The target compiler does not agree with configure '
                        'about the target bitness.')


option(env='BINDGEN_CFLAGS',
       nargs=1,
       default=bindgen_cflags_defaults,
       help='Options bindgen should pass to the C/C++ parser')


@depends('BINDGEN_CFLAGS')
@checking('bindgen cflags', lambda s: s if s else 'no')
def bindgen_cflags(value):
    if value and len(value):
        return value[0].split()


add_old_configure_assignment('_BINDGEN_CFLAGS', bindgen_cflags)


@depends(c_compiler)
def default_debug_flags(compiler_info):
    # Debug info is ON by default.
    if compiler_info.type in ('msvc', 'clang-cl'):
        return '-Zi'
    return '-g'


option(env='MOZ_DEBUG_FLAGS',
       nargs=1,
       help='Debug compiler flags')

imply_option('--enable-debug-symbols',
             depends_if('--enable-debug')(lambda v: v))

js_option('--enable-debug-symbols',
          nargs='?',
          default=True,
          help='Enable debug symbols using the given compiler flags')

set_config('MOZ_DEBUG_SYMBOLS',
           depends_if('--enable-debug-symbols')(lambda _: True))


@depends('MOZ_DEBUG_FLAGS', '--enable-debug-symbols', default_debug_flags)
def debug_flags(env_debug_flags, enable_debug_flags, default_debug_flags):
    # If MOZ_DEBUG_FLAGS is set, and --enable-debug-symbols is set to a value,
    # --enable-debug-symbols takes precedence. Note, the value of
    # --enable-debug-symbols may be implied by --enable-debug.
    if len(enable_debug_flags):
        return enable_debug_flags[0]
    if env_debug_flags:
        return env_debug_flags[0]
    return default_debug_flags


set_config('MOZ_DEBUG_FLAGS', debug_flags)
add_old_configure_assignment('MOZ_DEBUG_FLAGS', debug_flags)


@depends(c_compiler)
def color_cflags(info):
    # We could test compiling with flags. By why incur the overhead when
    # color support should always be present in a specific toolchain
    # version?

    # Code for auto-adding this flag to compiler invocations needs to
    # determine if an existing flag isn't already present. That is likely
    # using exact string matching on the returned value. So if the return
    # value changes to e.g. "<x>=always", exact string match may fail and
    # multiple color flags could be added. So examine downstream consumers
    # before adding flags to return values.
    if info.type == 'gcc':
        return '-fdiagnostics-color'
    elif info.type == 'clang':
        return '-fcolor-diagnostics'
    else:
        return ''


set_config('COLOR_CFLAGS', color_cflags)

# Some standard library headers (notably bionic on Android) declare standard
# functions (e.g. getchar()) and also #define macros for those standard
# functions.  libc++ deals with this by doing something like the following
# (explanatory comments added):
#
#   #ifdef FUNC
#   // Capture the definition of FUNC.
#   inline _LIBCPP_INLINE_VISIBILITY int __libcpp_FUNC(...) { return FUNC(...); }
#   #undef FUNC
#   // Use a real inline definition.
#   inline _LIBCPP_INLINE_VISIBILITY int FUNC(...) { return _libcpp_FUNC(...); }
#   #endif
#
# _LIBCPP_INLINE_VISIBILITY is typically defined as:
#
#   __attribute__((__visibility__("hidden"), __always_inline__))
#
# Unfortunately, this interacts badly with our system header wrappers, as the:
#
#   #pragma GCC visibility push(default)
#
# that they do prior to including the actual system header is treated by the
# compiler as an explicit declaration of visibility on every function declared
# in the header.  Therefore, when the libc++ code above is encountered, it is
# as though the compiler has effectively seen:
#
#   int FUNC(...) __attribute__((__visibility__("default")));
#   int FUNC(...) __attribute__((__visibility__("hidden")));
#
# and the compiler complains about the mismatched visibility declarations.
#
# However, libc++ will only define _LIBCPP_INLINE_VISIBILITY if there is no
# existing definition.  We can therefore define it to the empty string (since
# we are properly managing visibility ourselves) and avoid this whole mess.
# Note that we don't need to do this with gcc, as libc++ detects gcc and
# effectively does the same thing we are doing here.
#
# _LIBCPP_ALWAYS_INLINE needs similar workarounds, since it too declares
# hidden visibility.


@depends(c_compiler, target)
def libcxx_override_visibility(c_compiler, target):
    if c_compiler.type == 'clang' and target.os == 'Android':
        return ''


set_define('_LIBCPP_INLINE_VISIBILITY', libcxx_override_visibility)
set_define('_LIBCPP_INLINE_VISIBILITY_EXCEPT_GCC49',
           libcxx_override_visibility)
set_define('_LIBCPP_ALWAYS_INLINE', libcxx_override_visibility)
set_define('_LIBCPP_ALWAYS_INLINE_EXCEPT_GCC49', libcxx_override_visibility)


@depends(target, check_build_environment)
def visibility_flags(target, env):
    if target.os != 'WINNT':
        if target.kernel == 'Darwin':
            return ('-fvisibility=hidden', '-fvisibility-inlines-hidden')
        return ('-I%s/system_wrappers' % os.path.join(env.dist),
                '-include',
                '%s/config/gcc_hidden.h' % env.topsrcdir)


@depends(target, visibility_flags)
def wrap_system_includes(target, visibility_flags):
    if visibility_flags and target.kernel != 'Darwin':
        return True


set_define('HAVE_VISIBILITY_HIDDEN_ATTRIBUTE',
           depends(visibility_flags)(lambda v: bool(v) or None))
set_define('HAVE_VISIBILITY_ATTRIBUTE',
           depends(visibility_flags)(lambda v: bool(v) or None))
set_config('WRAP_SYSTEM_INCLUDES', wrap_system_includes)
set_config('VISIBILITY_FLAGS', visibility_flags)


@depends(c_compiler)
@imports('multiprocessing')
@imports(_from='__builtin__', _import='min')
def pgo_flags(compiler):
    if compiler.type in ('gcc', 'clang'):
        return namespace(
            gen_cflags=['-fprofile-generate'],
            gen_ldflags=['-fprofile-generate'],
            use_cflags=['-fprofile-use', '-fprofile-correction',
                        '-Wcoverage-mismatch'],
            use_ldflags=['-fprofile-use'],
        )

    if compiler.type == 'msvc':
        num_cores = min(8, multiprocessing.cpu_count())
        cgthreads = '-CGTHREADS:%s' % num_cores

        return namespace(
            gen_cflags=['-GL'],
            gen_ldflags=['-LTCG:PGINSTRUMENT', '-PogoSafeMode', cgthreads],
            # XXX: PGO builds can fail with warnings treated as errors,
            # specifically "no profile data available" appears to be
            # treated as an error sometimes. This might be a consequence
            # of using WARNINGS_AS_ERRORS in some modules, combined
            # with the linker doing most of the work in the whole-program
            # optimization/PGO case. I think it's probably a compiler bug,
            # but we work around it here.
            use_cflags=['-GL', '-wd4624', '-wd4952'],
            # XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
            # Probably also a compiler bug, but what can you do?
            # /d2:-cgsummary prints a summary of what is happening during
            # code generation. How long individual functions are optimized,
            # which functions are optimized, etc.
            use_ldflags=['-LTCG:PGUPDATE', cgthreads, '-d2:-cgsummary'],
        )


set_config('PROFILE_GEN_CFLAGS', pgo_flags.gen_cflags)
set_config('PROFILE_GEN_LDFLAGS', pgo_flags.gen_ldflags)
set_config('PROFILE_USE_CFLAGS', pgo_flags.use_cflags)
set_config('PROFILE_USE_LDFLAGS', pgo_flags.use_ldflags)


@depends(c_compiler)
def preprocess_option(compiler):
    # The uses of PREPROCESS_OPTION depend on the spacing for -o/-Fi.
    if compiler.type in ('gcc', 'clang'):
        return '-E -o '
    else:
        return '-P -Fi'


set_config('PREPROCESS_OPTION', preprocess_option)


# We only want to include windows.configure when we are compiling on
# Windows, for Windows.


@depends(target, host)
def is_windows(target, host):
    return host.kernel == 'WINNT' and target.kernel == 'WINNT'


include('windows.configure', when=is_windows)

# Shader Compiler for Windows (and MinGW Cross Compile)
# ==============================================================

fxc = check_prog('FXC', ('fxc.exe', 'fxc2.exe'), when=depends(target)
                 (lambda t: t.kernel == 'WINNT'))
wine = check_prog('WINE', ['wine'], when=depends(target, host)
                  (lambda t, h: t.kernel == 'WINNT' and h.kernel == 'Linux'))

# LTO
# ==============================================================

js_option('--enable-lto',
          nargs='?',
          choices=('full', 'thin'),
          help='Enable LTO')


@depends('--enable-lto', c_compiler)
@imports('multiprocessing')
def lto(value, c_compiler):
    flags = []
    ldflags = []

    # clang and clang-cl
    if c_compiler.type in ('clang', 'clang-cl'):
        # Until Bug 1457168 is fixed, we have to hardcode -fuse-ld=lld here
        if c_compiler.type == 'clang':
            flags.append("-fuse-ld=lld")

        if len(value) and value[0].lower() == 'full':
            flags.append("-flto")
            ldflags.append("-flto")
        elif value:
            flags.append("-flto=thin")
            ldflags.append("-flto=thin")

    # gcc and other compilers
    elif value:
        num_cores = multiprocessing.cpu_count()
        flags.append("-flto")
        flags.append("-flifetime-dse=1")

        ldflags.append("-flto=%s" % num_cores)
        ldflags.append("-flifetime-dse=1")

    return namespace(
        enabled="1" if value else None,
        flags=flags,
        ldflags=ldflags
    )


add_old_configure_assignment('MOZ_LTO', lto.enabled)
add_old_configure_assignment('MOZ_LTO_CFLAGS', lto.flags)
add_old_configure_assignment('MOZ_LTO_LDFLAGS', lto.ldflags)

imply_option('--enable-linker', 'lld', when='--enable-lto')

# ASAN
# ==============================================================

js_option('--enable-address-sanitizer', help='Enable Address Sanitizer')


@depends_if('--enable-address-sanitizer')
def asan(value):
    return True


add_old_configure_assignment('MOZ_ASAN', asan)


# Security Hardening
# ==============================================================

option('--enable-hardening', env='MOZ_SECURITY_HARDENING',
       help='Enables security hardening compiler options')


@depends('--enable-hardening', '--enable-address-sanitizer',
         '--enable-optimize', c_compiler, target)
def security_hardening_cflags(hardening_flag, asan, optimize, c_compiler, target):
    compiler_is_gccish = c_compiler.type in ('gcc', 'clang')

    flags = []
    js_flags = []

    # FORTIFY_SOURCE ------------------------------------
    # If hardening is explicitly enabled, or not explicitly disabled
    if hardening_flag.origin == "default" or hardening_flag:
        # Require optimization for FORTIFY_SOURCE. See Bug 1417452
        # Also, undefine it before defining it just in case a distro adds it, see Bug 1418398
        if compiler_is_gccish and optimize and not asan:
            # Don't enable FORTIFY_SOURCE on Android on the top-level, but do enable in js/
            if target.os != 'Android':
                flags.append("-U_FORTIFY_SOURCE")
                flags.append("-D_FORTIFY_SOURCE=2")
            js_flags.append("-U_FORTIFY_SOURCE")
            js_flags.append("-D_FORTIFY_SOURCE=2")

    # If ASAN _is_ on, undefine FOTIFY_SOURCE just to be safe
    if asan:
        flags.append("-U_FORTIFY_SOURCE")
        js_flags.append("-U_FORTIFY_SOURCE")

    # fstack-protector ------------------------------------
    # Enable only if --enable-hardening is passed and ASAN is
    # not on as ASAN will catch the crashes for us
    if hardening_flag and compiler_is_gccish and not asan:
        flags.append("-fstack-protector-strong")

    # fno-common -----------------------------------------
    # Do not merge variables for ASAN; can detect some subtle bugs
    if asan:
        # clang-cl does not recognize the flag, it must be passed down to clang
        if c_compiler.type == 'clang-cl':
            flags.append("-Xclang")
        flags.append("-fno-common")

    return namespace(
        flags=flags,
        js_flags=js_flags,
    )


add_old_configure_assignment('MOZ_HARDENING_CFLAGS', security_hardening_cflags.flags)
add_old_configure_assignment('MOZ_HARDENING_CFLAGS_JS', security_hardening_cflags.js_flags)
imply_option('--enable-pie', depends_if('--enable-hardening')(lambda v: v))

# Code Coverage
# ==============================================================

js_option('--enable-coverage', env='MOZ_CODE_COVERAGE',
          help='Enable code coverage')


@depends('--enable-coverage')
def code_coverage(value):
    if value:
        return True


set_config('MOZ_CODE_COVERAGE', code_coverage)
set_define('MOZ_CODE_COVERAGE', code_coverage)

# ==============================================================

option(env='RUSTFLAGS',
       nargs=1,
       help='Rust compiler flags')
set_config('RUSTFLAGS', depends('RUSTFLAGS')(lambda flags: flags))


# Rust compiler flags
# ==============================================================

js_option(env='RUSTC_OPT_LEVEL',
          nargs=1,
          help='Rust compiler optimization level (-C opt-level=%s)')

# --enable-release kicks in full optimizations.
imply_option('RUSTC_OPT_LEVEL', '2', when='--enable-release')


@depends('RUSTC_OPT_LEVEL', moz_optimize)
def rustc_opt_level(opt_level_option, moz_optimize):
    if opt_level_option:
        return opt_level_option[0]
    else:
        return '1' if moz_optimize.optimize else '0'


@depends(rustc_opt_level, debug_rust, '--enable-debug-symbols')
def rust_compiler_flags(opt_level, debug_rust, debug_symbols):
    # Cargo currently supports only two interesting profiles for building:
    # development and release. Those map (roughly) to --enable-debug and
    # --disable-debug in Gecko, respectively.
    #
    # But we'd also like to support an additional axis of control for
    # optimization level. Since Cargo only supports 2 profiles, we're in
    # a bit of a bind.
    #
    # Code here derives various compiler options given other configure options.
    # The options defined here effectively override defaults specified in
    # Cargo.toml files.

    debug_assertions = None
    debug_info = None

    # opt-level=0 implies -C debug-assertions, which may not be desired
    # unless Rust debugging is enabled.
    if opt_level == '0' and not debug_rust:
        debug_assertions = False

    if debug_symbols:
        debug_info = '2'

    opts = []

    if opt_level is not None:
        opts.append('opt-level=%s' % opt_level)
    if debug_assertions is not None:
        opts.append('debug-assertions=%s' %
                    ('yes' if debug_assertions else 'no'))
    if debug_info is not None:
        opts.append('debuginfo=%s' % debug_info)

    flags = []
    for opt in opts:
        flags.extend(['-C', opt])

    return flags


set_config('MOZ_RUST_DEFAULT_FLAGS', rust_compiler_flags)

# Rust incremental compilation
# ==============================================================


@depends(rustc_opt_level, debug_rust, 'MOZ_AUTOMATION', code_coverage)
def cargo_incremental(opt_level, debug_rust, automation, code_coverage):
    """Return a value for the CARGO_INCREMENTAL environment variable."""

    # We never want to use incremental compilation in automation.  sccache
    # handles our automation use case much better than incremental compilation
    # would.
    if automation:
        return '0'

    # Coverage instrumentation doesn't play well with incremental compilation
    # https://github.com/rust-lang/rust/issues/50203.
    if code_coverage:
        return '0'

    # Incremental compilation is automatically turned on for debug builds, so
    # we don't need to do anything special here.
    if debug_rust:
        return

    # --enable-release automatically sets -O2 for Rust code, and people can
    # set RUSTC_OPT_LEVEL to 2 or even 3 if they want to profile Rust code.
    # Let's assume that if Rust code is using -O2 or higher, we shouldn't
    # be using incremental compilation, because we'd be imposing a
    # significant runtime cost.
    if opt_level not in ('0', '1'):
        return

    # We're clear to use incremental compilation!
    return '1'


set_config('CARGO_INCREMENTAL', cargo_incremental)

# Linker detection
# ==============================================================


@depends(target)
def is_linker_option_enabled(target):
    if target.kernel not in ('Darwin', 'WINNT', 'SunOS'):
        return True


option('--enable-gold',
       env='MOZ_FORCE_GOLD',
       help='Enable GNU Gold Linker when it is not already the default',
       when=is_linker_option_enabled)

imply_option('--enable-linker', 'gold', when='--enable-gold')

js_option('--enable-linker', nargs=1,
          help='Select the linker {bfd, gold, lld, lld-*}',
          when=is_linker_option_enabled)


@depends('--enable-linker', c_compiler, developer_options, '--enable-gold',
         extra_toolchain_flags, when=is_linker_option_enabled)
@checking('for linker', lambda x: x.KIND)
@imports('os')
@imports('shutil')
def select_linker(linker, c_compiler, developer_options, enable_gold,
                  toolchain_flags):

    linker = linker[0] if linker else None

    if linker not in ('bfd', 'gold', 'lld', None) and not linker.startswith("lld-"):
        # Check that we are trying to use a supported linker
        die('Unsupported linker ' + linker)

    # Check the kind of linker
    version_check = ['-Wl,--version']
    cmd_base = c_compiler.wrapper + [c_compiler.compiler] + c_compiler.flags

    def try_linker(linker):
        # Generate the compiler flag
        linker_flag = ["-fuse-ld=" + linker] if linker else []
        cmd = cmd_base + linker_flag + version_check
        if toolchain_flags:
            cmd += toolchain_flags

        cmd_output = check_cmd_output(*cmd).decode('utf-8')
        if 'GNU ld' in cmd_output:
            # We are using the normal linker
            kind = 'bfd'

        elif 'GNU gold' in cmd_output:
            kind = 'gold'

        elif 'LLD' in cmd_output:
            kind = 'lld'

        else:
            kind = 'unknown'

        return namespace(
            KIND=kind,
            LINKER_FLAG=linker_flag,
        )

    result = try_linker(linker)

    if (linker is None and enable_gold.origin == 'default' and
            developer_options and result.KIND == 'bfd'):
        gold = try_linker('gold')

        if gold.KIND == 'gold':
            result = gold

    # If an explicit linker was given, error out if what we found is different.
    if linker and not linker.startswith(result.KIND):
        die("Could not use {} as linker".format(linker))

    return result


set_config('LD_IS_BFD', depends(select_linker.KIND)
           (lambda x: x == 'bfd' or None))
set_config('LINKER_LDFLAGS', select_linker.LINKER_FLAG)


js_option('--enable-clang-plugin', env='ENABLE_CLANG_PLUGIN',
          help="Enable building with the mozilla clang plugin")

add_old_configure_assignment('ENABLE_CLANG_PLUGIN',
                             depends_if('--enable-clang-plugin')(lambda _: True))

js_option('--enable-mozsearch-plugin', env='ENABLE_MOZSEARCH_PLUGIN',
          help="Enable building with the mozsearch indexer plugin")

add_old_configure_assignment('ENABLE_MOZSEARCH_PLUGIN',
                             depends_if('--enable-mozsearch-plugin')(lambda _: True))

# Libstdc++ compatibility hacks
# ==============================================================
#
js_option('--enable-stdcxx-compat', env='MOZ_STDCXX_COMPAT',
          help='Enable compatibility with older libstdc++')


@template
def libstdcxx_version(var, compiler):
    @depends(compiler, when='--enable-stdcxx-compat')
    @imports(_from='mozbuild.configure.libstdcxx', _import='find_version')
    def version(compiler):
        result = find_version(
            compiler.wrapper + [compiler.compiler] + compiler.flags)
        if result:
            return str(result)

    set_config(var, version)
    return version


add_gcc_flag(
    '-D_GLIBCXX_USE_CXX11_ABI=0', cxx_compiler,
    when=libstdcxx_version('MOZ_LIBSTDCXX_TARGET_VERSION', cxx_compiler))
add_gcc_flag(
    '-D_GLIBCXX_USE_CXX11_ABI=0', host_cxx_compiler,
    when=libstdcxx_version('MOZ_LIBSTDCXX_HOST_VERSION', host_cxx_compiler))


@depends(c_compiler.try_compile(flags=['-fsanitize=fuzzer-no-link'],
         check_msg='whether the C compiler supports -fsanitize=fuzzer-no-link'))
def have_libfuzzer_flag_fuzzer_no_link(value):
    if value:
        return True


set_config('HAVE_LIBFUZZER_FLAG_FUZZER_NO_LINK', have_libfuzzer_flag_fuzzer_no_link)