toolkit/moz.configure
author Ralph Giles <giles@mozilla.com>
Tue, 25 Jul 2017 14:29:52 -0700
changeset 371467 b18177e6556b8e31b3b0900aed456d8a2698792d
parent 369660 e79bfc74d1495dc1ce78d5a2791169ee6aabfaef
child 372556 55cfa8df80a4ce36ca96e342bc379b7dcead3111
permissions -rw-r--r--
Bug 1384258 - Build Stylo by default. r=chmanchester Build Stylo (the styling system from servo) by default in all builds for win32, win64, macOS and linux64 targets. It was previously enabled for automation builds, so this just changes the behaviour for local developer builds. Note that this introduces a new dependency on libclang for the binding generator. If you're developing on a tier-1 platform, run `./mach boostrap` to install a working copy. Otherwise llvm+libclang 4.0.1 is recommended. Remove the explicit --enable-stylo=build in mozconfig.stylo in favour of the configure default. Add mozconfig.stylo to the hazard and debug-asan mozconfigs so LLVM_CONFIG is defined properly for those builds. Based on a patch by Bobby Holly in bug 1356991. MozReview-Commit-ID: C2wRNl7JHpz

# -*- 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/.


# Profiling
# ==============================================================
# Some of the options here imply an option from js/moz.configure,
# so, need to be declared before the include.

option('--enable-jprof', env='MOZ_JPROF',
       help='Enable jprof profiling tool (needs mozilla/tools/jprof)')

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

set_config('MOZ_JPROF', jprof)
set_define('MOZ_JPROF', jprof)
imply_option('--enable-profiling', jprof)

@depends(target)
def gecko_profiler(target):
    if target.os == 'Android':
        return target.cpu in ('aarch64', 'arm', 'x86')
    elif target.kernel == 'Linux':
        return target.cpu in ('x86', 'x86_64')
    return target.os in ('OSX', 'WINNT')

@depends(gecko_profiler)
def gecko_profiler_define(value):
    if value:
        return True

set_config('MOZ_GECKO_PROFILER', gecko_profiler_define)
set_define('MOZ_GECKO_PROFILER', gecko_profiler_define)


option('--enable-dmd', env='MOZ_DMD',
       help='Enable Dark Matter Detector (heap profiler). '
            'Also enables jemalloc, replace-malloc and profiling')

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

set_config('MOZ_DMD', dmd)
set_define('MOZ_DMD', dmd)
add_old_configure_assignment('MOZ_DMD', dmd)
imply_option('--enable-profiling', dmd)
imply_option('--enable-jemalloc', dmd)
imply_option('--enable-replace-malloc', dmd)

# JACK cubeb backend
# ==============================================================
option('--enable-jack', env='MOZ_JACK',
       help='Enable JACK audio backend.')

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

set_config('MOZ_JACK', jack)
set_define('MOZ_JACK', jack)

# Javascript engine
# ==============================================================
include('../js/moz.configure')


# Rust
# ==============================================================
include('../build/moz.configure/rust.configure',
        when='--enable-compile-environment')


# L10N
# ==============================================================
option('--with-l10n-base', nargs=1, env='L10NBASEDIR',
       help='Path to l10n repositories')

@depends('--with-l10n-base')
@imports(_from='os.path', _import='isdir')
def l10n_base(value):
    if value:
        path = value[0]
        if not isdir(path):
            die("Invalid value --with-l10n-base, %s doesn't exist", path)
        return os.path.realpath(os.path.abspath(path))

set_config('L10NBASEDIR', l10n_base)


# Default toolkit
# ==============================================================
# Normally, we'd want to use the `default` field on the option, but that
# requires --target to be resolved at --help time, which requires to run
# config.guess, which we want to avoid. Even better, we could actually set
# `choices` depending on the target, but that doesn't pan out for the same
# reason.
option('--enable-default-toolkit', nargs=1,
       choices=('cairo-windows', 'cairo-gtk3', 'cairo-gtk3-wayland',
                'cairo-cocoa', 'cairo-uikit', 'cairo-android'),
       help='Select default toolkit')

@depends('--enable-default-toolkit', target, '--help')
def toolkit(value, target, _):
    # Define possible choices for each platform. The default is the first one
    # listed when there are several.
    os = target.os
    if target.os == 'WINNT':
        platform_choices = ('cairo-windows',)
    elif target.os == 'OSX':
        platform_choices = ('cairo-cocoa',)
    elif target.os == 'iOS':
        platform_choices = ('cairo-uikit',)
    elif target.os == 'Android':
        if value.origin == 'implied':
            # Trust values coming from imply_option() (used in
            # b2g/moz.configure).
            platform_choices = tuple(value)
        else:
            platform_choices = ('cairo-android',)
    else:
        platform_choices = ('cairo-gtk3', 'cairo-gtk3-wayland')

    if value:
        if value[0] not in platform_choices:
            die('`%s` is not a valid value for --enable-default-toolkit on %s\n'
                'Valid values: %s', value[0], os, ', '.join(platform_choices))
        return value[0]

    return platform_choices[0]

@depends(toolkit)
def wayland(toolkit):
    return toolkit == 'cairo-gtk3-wayland'

@depends(toolkit)
def toolkit(toolkit):
    if toolkit == 'cairo-gtk2-x11':
        widget_toolkit = 'gtk2'
    elif toolkit == 'cairo-gtk3-wayland' :
        widget_toolkit = 'gtk3'
    else:
        widget_toolkit = toolkit.replace('cairo-', '')
    return widget_toolkit

set_config('MOZ_WIDGET_TOOLKIT', toolkit)
add_old_configure_assignment('MOZ_WIDGET_TOOLKIT', toolkit)

@depends(toolkit)
def toolkit_gtk(toolkit):
    if toolkit == 'gtk2':
        return '2'
    elif toolkit == 'gtk3':
        return '3'

set_define('MOZ_WIDGET_GTK', toolkit_gtk)

@depends(toolkit)
def toolkit_define(toolkit):
    if toolkit not in ('gtk2', 'gtk3', 'windows'):
        return 'MOZ_WIDGET_%s' % toolkit.upper()

set_define(toolkit_define, True)


option('--without-x', env='WITHOUT_X', help='Disable X11 support')

@depends('--without-x', toolkit)
def x11(value, toolkit):
    if not value:
        die('--without-x is not supported')

    x11_toolkits = ('gtk2', 'gtk3')
    if value and value.origin != 'default' and toolkit not in x11_toolkits:
        die('--with-x is only valid with --enable-default-toolkit={%s}',
            ','.join(x11_toolkits))

    return True if value and toolkit in x11_toolkits else None

set_config('MOZ_ENABLE_XREMOTE', x11)
set_define('MOZ_ENABLE_XREMOTE', x11)
set_config('MOZ_X11', x11)
set_define('MOZ_X11', x11)
add_old_configure_assignment('MOZ_X11', x11)

# Wayland support
# ==============================================================
wayland_headers = pkg_check_modules('MOZ_WAYLAND', 'gtk+-wayland-3.0 >= 3.22',
                                    when=wayland)

set_config('MOZ_WAYLAND', depends_if(wayland_headers)(lambda _: True))
set_define('MOZ_WAYLAND', depends_if(wayland_headers)(lambda _: True))

# GL Provider
# ==============================================================
option('--with-gl-provider', nargs=1, help='Set GL provider backend type')

@depends('--with-gl-provider')
def gl_provider(value):
    if value:
        return value[0]

@depends(gl_provider)
def gl_provider_define(provider):
    if provider:
        return 'GLContextProvider%s' % provider

set_define('MOZ_GL_PROVIDER', gl_provider_define)

@depends(gl_provider, x11)
def gl_default_provider(value, x11):
    if value:
        return value
    elif x11:
        return 'GLX'

set_config('MOZ_GL_PROVIDER', gl_provider)
set_config('MOZ_GL_DEFAULT_PROVIDER', gl_default_provider)

@depends(gl_default_provider)
def gl_provider_define(provider):
    if provider:
        return 'GL_PROVIDER_%s' % provider

set_define(gl_provider_define, True)


# PDF printing
# ==============================================================
@depends(toolkit)
def pdf_printing(toolkit):
    if toolkit in ('windows', 'gtk2', 'gtk3', 'android'):
        return True

@depends(pdf_printing)
def pdf_surface_feature(pdf_printing):
    if pdf_printing:
        return '#define CAIRO_HAS_PDF_SURFACE 1'
    else:
        # CONFIGURE_SUBST_FILES need explicit empty values.
        return ''

set_config('MOZ_PDF_PRINTING', pdf_printing)
set_config('PDF_SURFACE_FEATURE', pdf_surface_feature)


# Event loop instrumentation
# ==============================================================
option(env='MOZ_INSTRUMENT_EVENT_LOOP',
       help='Force-enable event loop instrumentation')

@depends('MOZ_INSTRUMENT_EVENT_LOOP', toolkit)
def instrument_event_loop(value, toolkit):
    if value or (toolkit in ('windows', 'gtk2', 'gtk3', 'cocoa', 'android') and
                 value.origin == 'default'):
        return True

set_config('MOZ_INSTRUMENT_EVENT_LOOP', instrument_event_loop)
set_define('MOZ_INSTRUMENT_EVENT_LOOP', instrument_event_loop)


# Fontconfig Freetype
# ==============================================================
option(env='USE_FC_FREETYPE',
       help='Force-enable the use of fontconfig freetype')

@depends('USE_FC_FREETYPE', toolkit)
def fc_freetype(value, toolkit):
    if value or (toolkit in ('gtk2', 'gtk3') and
                 value.origin == 'default'):
        return True

add_old_configure_assignment('USE_FC_FREETYPE', fc_freetype)

# Pango
# ==============================================================
pkg_check_modules('MOZ_PANGO',
                  'pango >= 1.22.0 pangoft2 >= 1.22.0 pangocairo >= 1.22.0',
                  when=toolkit_gtk)

# Fontconfig
# ==============================================================
fontconfig_info = pkg_check_modules('_FONTCONFIG', 'fontconfig >= 2.7.0',
                                    when=fc_freetype)

@depends(fc_freetype)
def check_for_freetype2(fc_freetype):
    if fc_freetype:
        return True

# Check for freetype2. Flags are combined with fontconfig flags.
freetype2_info = pkg_check_modules('_FT2', 'freetype2 >= 6.1.0',
                                   when=check_for_freetype2)

@depends(fontconfig_info, freetype2_info)
def freetype2_combined_info(fontconfig_info, freetype2_info):
    if not freetype2_info:
        return
    if not fontconfig_info:
        return freetype2_info
    return namespace(
        cflags=freetype2_info.cflags + fontconfig_info.cflags,
        libs=freetype2_info.libs + fontconfig_info.libs,
    )

add_old_configure_assignment('_HAVE_FREETYPE2',
                             depends_if(freetype2_info)(lambda _: True))

# Apple platform decoder support
# ==============================================================
@depends(toolkit)
def applemedia(toolkit):
    if toolkit in ('cocoa', 'uikit'):
        return True

set_config('MOZ_APPLEMEDIA', applemedia)
set_define('MOZ_APPLEMEDIA', applemedia)
add_old_configure_assignment('MOZ_APPLEMEDIA', applemedia)

# Windows Media Foundation support
# ==============================================================
option('--disable-wmf',
       help='Disable support for Windows Media Foundation')

@depends('--disable-wmf', target)
def wmf(value, target):
    enabled = bool(value)
    if value.origin == 'default':
        # Enable Windows Media Foundation support by default.
        # Note our minimum SDK version is Windows 7 SDK, so we are (currently)
        # guaranteed to have a recent-enough SDK to build WMF.
        enabled = target.os == 'WINNT'
    if enabled and target.os != 'WINNT':
        die('Cannot enable Windows Media Foundation support on %s', target.os)
    if enabled:
        return True

set_config('MOZ_WMF', wmf)
set_define('MOZ_WMF', wmf)

# FFmpeg H264/AAC Decoding Support
# ==============================================================
option('--disable-ffmpeg',
       help='Disable FFmpeg for fragmented H264/AAC decoding')

@depends('--disable-ffmpeg', target)
def ffmpeg(value, target):
    enabled = bool(value)
    if value.origin == 'default':
        enabled = target.os not in ('Android', 'WINNT')
    if enabled:
        return True

set_config('MOZ_FFMPEG', ffmpeg)
set_define('MOZ_FFMPEG', ffmpeg)
imply_option('--enable-fmp4', ffmpeg, '--enable-ffmpeg')

# Libaom AV1 Video Codec Support
# ==============================================================
option('--enable-av1',
        help='Enable libaom for av1 video support')

@depends('--enable-av1', target, milestone)
def av1(value, target, milestone):
    enabled = bool(value)
    if value.origin == 'default' and milestone.is_nightly:
        enabled = target.os != 'Android'
    if enabled:
        return True

set_config('MOZ_AV1', av1)
set_define('MOZ_AV1', av1)

# Built-in fragmented MP4 support.
# ==============================================================
option('--disable-fmp4', env='MOZ_FMP4',
       help='Disable support for in built Fragmented MP4 parsing')

@depends('--disable-fmp4', target, wmf, applemedia)
def fmp4(value, target, wmf, applemedia):
    enabled = bool(value)
    if value.origin == 'default':
        # target.os == 'Android' includes all B2G versions
        enabled = wmf or applemedia or target.os == 'Android'
    if enabled:
        return True

set_config('MOZ_FMP4', fmp4)
set_define('MOZ_FMP4', fmp4)
add_old_configure_assignment('MOZ_FMP4', fmp4)

# EME Support
# ==============================================================
# Widevine is enabled by default in desktop browser builds.
@depends(build_project, '--help')
def eme_default(build_project, help):
    if build_project == 'browser':
        return 'widevine'

option('--enable-eme',
       nargs='*',
       choices=('widevine',),
       default=eme_default,
       help='Enable support for Encrypted Media Extensions')

@depends('--enable-eme', target)
def enable_eme(value, target):
    # Widevine EME by default enabled on desktop Windows, MacOS and Linux,
    # x86 and x64 builds.
    if (target.kernel in ('Darwin', 'WINNT', 'Linux') and
        target.os not in ('Android', 'iOS') and
        target.cpu in ('x86', 'x86_64')):
        return value
    elif value and value.origin != 'default':
        die('%s is not supported on %s' % (value.format('--enable-eme'), target.alias))
    # Return the same type of OptionValue (Positive or Negative), with an empty tuple.
    return value.__class__(())

@depends(enable_eme, fmp4)
def eme(value, fmp4):
    enabled = bool(value)
    if value.origin == 'default':
        enabled = enabled or fmp4
    if enabled and not fmp4:
        die('Encrypted Media Extension support requires '
            'Fragmented MP4 support')
    if enabled:
        return True

@depends(enable_eme)
def eme_modules(value):
    return value

set_config('MOZ_EME_MODULES', eme_modules)

option(name='--enable-chrome-format',
       help='Select FORMAT of chrome files during packaging.',
       nargs=1,
       choices=('omni', 'jar', 'flat'),
       default='omni')

@depends('--enable-chrome-format')
def packager_format(value):
    return value[0]

set_config('MOZ_PACKAGER_FORMAT', packager_format)

@depends(host, build_project)
def jar_maker_format(host, build_project):
    # Multilocales for mobile/android use the same mergedirs for all locales,
    # so we can't use symlinks for those builds.
    if host.os == 'WINNT' or build_project == 'mobile/android':
        return 'flat'
    return 'symlink'

set_config('MOZ_JAR_MAKER_FILE_FORMAT', jar_maker_format)

@depends(toolkit)
def omnijar_name(toolkit):
    # Fennec's static resources live in the assets/ folder of the
    # APK.  Adding a path to the name here works because we only
    # have one omnijar file in the final package (which is not the
    # case on desktop), and necessitates some contortions during
    # packaging so that the resources in the omnijar are considered
    # as rooted at / and not as rooted at assets/ (which again is
    # not the case on desktop: there are omnijars rooted at webrtc/,
    # etc). packager.mk handles changing the rooting of the single
    # omnijar.
    return 'assets/omni.ja' if toolkit == 'android' else 'omni.ja'

set_config('OMNIJAR_NAME', omnijar_name)

project_flag('MOZ_PLACES',
             help='Build Places if required',
             set_as_define=True)

project_flag('MOZ_SOCIAL',
             help='Build SocialAPI if required',
             default=True)

project_flag('MOZ_SERVICES_HEALTHREPORT',
             help='Build Firefox Health Reporter Service',
             set_for_old_configure=True,
             set_as_define=True)

project_flag('MOZ_SERVICES_SYNC',
             help='Build Sync Services if required')

project_flag('MOZ_ANDROID_HISTORY',
             help='Enable Android History instead of Places',
             set_as_define=True)

project_flag('MOZ_ALLOW_LEGACY_EXTENSIONS',
             help='Allow legacy browser extensions',
             default=True, set_as_define=True)

option(env='MOZ_PHOTON_ANIMATIONS',
       help='Enable Photon UI animations',
       default=milestone.is_nightly)

@depends('MOZ_PHOTON_ANIMATIONS')
def photon_animations(value):
    if value:
        return bool(value)

set_config('MOZ_PHOTON_ANIMATIONS', photon_animations)
set_define('MOZ_PHOTON_ANIMATIONS', photon_animations)

option(env='MOZ_PHOTON_PREFERENCES',
       help='Enable Photon preferences',
       default=milestone.is_nightly)

@depends('MOZ_PHOTON_PREFERENCES')
def photon_preferences(value):
    if value:
        return bool(value)

set_config('MOZ_PHOTON_PREFERENCES', photon_preferences)
set_define('MOZ_PHOTON_PREFERENCES', photon_preferences)

option(env='MOZ_PHOTON_THEME',
       help='Enable Photon theme',
       default=milestone.is_nightly)

@depends('MOZ_PHOTON_THEME')
def photon_theme(value):
    if value:
        return bool(value)

set_config('MOZ_PHOTON_THEME', photon_theme)
set_define('MOZ_PHOTON_THEME', photon_theme)

@depends('MOZ_PLACES', 'MOZ_ANDROID_HISTORY')
def check_places_and_android_history(places, android_history):
    if places and android_history:
        die('Cannot use MOZ_ANDROID_HISTORY alongside MOZ_PLACES.')

# Permissions system
# ==============================================================
option(name='--disable-permissions',
       help='Disable permissions (popup and cookie blocking)')

moz_permissions = depends_if('--disable-permissions')(lambda _: True)

set_config('MOZ_PERMISSIONS', moz_permissions)
set_define('MOZ_PERMISSIONS', moz_permissions)

# gpsd support
# ==============================================================
option('--enable-gpsd', env='MOZ_GPSD',
       help='Enable gpsd support')

@depends('--enable-gpsd')
def gpsd(value):
    return bool(value)

system_gpsd = pkg_check_modules('MOZ_GPSD', 'libgps >= 3.11',
                                when=gpsd)

set_config('MOZ_GPSD', depends_if(system_gpsd)(lambda _: True))

# Miscellaneous programs
# ==============================================================

check_prog('TAR', ('gnutar', 'gtar', 'tar'))
check_prog('UNZIP', ('unzip',))
check_prog('ZIP', ('zip',))

# Key files
# ==============================================================
include('../build/moz.configure/keyfiles.configure')

simple_keyfile('Mozilla API')

simple_keyfile('Google API')

id_and_secret_keyfile('Bing API')

simple_keyfile('Adjust SDK')

id_and_secret_keyfile('Leanplum SDK')

# Servo integration
# ==============================================================
option('--enable-stylo', nargs='?', choices=('build',),
       help='Include Stylo in the build and/or enable it at runtime')

@depends('--enable-stylo', '--help', target)
def stylo_config(value, _, target):
    build_stylo = None
    enable_stylo = None

    # If nothing is specified, default to building stylo where possible.
    if value.origin == 'default':
        if target.os == 'GNU' and target.bitness == 32:
            # The clang setup we use in automation is a little unusual, and
            # doesn't play well with bindgen on 32-bit Linux.
            pass
        elif target.os == 'Android':
            # Stylo on Android is happening Later(tm).
            pass
        else:
            build_stylo = True
    elif len(value) and value[0] == 'build':
        # Build but disable by request.
        build_stylo = True
    elif bool(value):
        # Build and enable.
        build_stylo = True
        enable_stylo = True

    return namespace(
        build = build_stylo,
        enable = enable_stylo,
    )

option('--disable-stylo-build-bindgen',
       help='Disable build-time bindgen for Stylo')

@depends(stylo_config, '--enable-stylo-build-bindgen', '--enable-compile-environment')
def building_stylo_bindgen(stylo_config, bindgen_enabled, compile_environment):
    if not compile_environment:
        return False
    if not bindgen_enabled:
        return False
    return stylo_config.build

# We support setting up the appropriate options for Stylo's build-time
# bindings generation via setting LLVM_CONFIG or by providing explicit
# configure options.  The Windows installer of LLVM/Clang doesn't provide
# llvm-config, so we need both methods to support all of our tier-1
# platforms.
@depends(host)
@imports('which')
@imports('os')
@imports('subprocess')
def llvm_config_paths(host):
    llvm_config_progs = [
        'llvm-config-4.0',
        'llvm-config-mp-4.0',   # MacPorts' chosen naming scheme.
        'llvm-config40',
        'llvm-config-3.9',
        'llvm-config39',
        'llvm-config',
    ]

    # Homebrew on macOS doesn't make clang available on PATH, so we have to
    # look for it in non-standard places.
    if host.kernel == 'Darwin':
        try:
            brew = which.which('brew')
            brew_config = subprocess.check_output([brew, 'config']).strip()

            for line in brew_config.splitlines():
                if line.startswith('HOMEBREW_PREFIX'):
                    fields = line.split(None, 2)
                    prefix = fields[1] if len(fields) == 2 else ''
                    path = ['opt', 'llvm', 'bin', 'llvm-config']
                    llvm_config_progs.append(os.path.join(prefix, *path))
                    break
        except which.WhichError:
            # Homebrew not installed, which is fine.
            pass

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

    llvm_config_progs.append(bootstrap_llvm_config)

    return llvm_config_progs

llvm_config = check_prog('LLVM_CONFIG', llvm_config_paths,
                         when=building_stylo_bindgen,
                         what='llvm-config', allow_missing=True)

with only_when(building_stylo_bindgen):
    option('--with-libclang-path', nargs=1,
           help='Absolute path to a directory containing Clang/LLVM libraries for Stylo (version 3.9.x or above)')
    option('--with-clang-path', nargs=1,
           help='Absolute path to a Clang binary for Stylo bindgen (version 3.9.x or above)')

    def invoke_llvm_config(llvm_config, *options):
        '''Invoke llvm_config with the given options and return the first line of
        output.'''
        lines = check_cmd_output(llvm_config, *options).splitlines()
        return lines[0]

    @imports(_from='textwrap', _import='dedent')
    def check_minimum_llvm_config_version(llvm_config):
        version = Version(invoke_llvm_config(llvm_config, '--version'))
        min_version = Version('3.9.0')
        if version < min_version:
            die(dedent('''\
            llvm installation {} is incompatible with Stylo bindgen.

            To compile Stylo, please install version {} or greater of
            Clang + LLVM and ensure that the 'llvm-config' from that
            installation is first on your path.

            You can verify this by typing 'llvm-config --version'.
            '''.format(version, min_version)))

    @depends(llvm_config, '--with-libclang-path', '--with-clang-path',
             host_library_name_info, host)
    @imports('os.path')
    @imports(_from='textwrap', _import='dedent')
    def bindgen_config_paths(llvm_config, libclang_path, clang_path,
                             library_name_info, host):
        def search_for_libclang(path):
            # Try to ensure that the clang shared library that bindgen is going
            # to look for is actually present.  The files that we search for
            # mirror the logic in clang-sys/build.rs.
            libclang_choices = []
            if host.os == 'WINNT':
                libclang_choices.append('libclang.dll')
            libclang_choices.append('%sclang%s' % (library_name_info.dll.prefix,
                                                   library_name_info.dll.suffix))
            if host.kernel == 'Linux':
                libclang_choices.append('libclang.so.1')

            # At least one of the choices must be found.
            for choice in libclang_choices:
                libclang = os.path.join(path, choice)
                if os.path.exists(libclang):
                    return (True, None)
            else:
                return (False, list(set(libclang_choices)))

        if not libclang_path and not clang_path:
            # We must have LLVM_CONFIG in this case.
            if not llvm_config:
                die(dedent('''\
                Could not find LLVM/Clang installation for compiling stylo build-time
                bindgen.  Please specify the 'LLVM_CONFIG' environment variable
                (recommended), pass the '--with-libclang-path' and '--with-clang-path'
                options to configure, or put 'llvm-config' in your PATH.  Altering your
                PATH may expose 'clang' as well, potentially altering your compiler,
                which may not be what you intended.'''))

            check_minimum_llvm_config_version(llvm_config)
            libclang_arg = '--bindir' if host.os == 'WINNT' else '--libdir'
            libclang_path = invoke_llvm_config(llvm_config, libclang_arg)
            clang_path = os.path.join(invoke_llvm_config(llvm_config, '--bindir'),
                                      'clang')
            libclang_path = normsep(libclang_path)
            clang_path = normsep(clang_path)

            # Debian-based distros, at least, can have llvm-config installed
            # but not have other packages installed.  Since the user is trying
            # to use their system packages, we can't be more specific about what
            # they need.
            if not os.path.exists(libclang_path):
                die(dedent('''\
                The directory {} returned by `llvm-config {}` does not exist.
                Please check your system configuration.
                '''.format(libclang_path, libclang_arg)))

            (found, searched) = search_for_libclang(libclang_path)
            if not found:
                die(dedent('''\
                Could not find the clang shared library in the path {}
                returned by `llvm-config {}` (searched for files {}).
                Please check your system configuration.
                '''.format(libclang_path, libclang_arg, searched)))

            clang_resolved = find_program(clang_path)
            if not clang_resolved:
                die(dedent('''\
                The file {} returned by `llvm-config {}` does not exist.
                Please check your system configuration.
                '''.format(clang_path, '--bindir')))

            return namespace(
                libclang_path=libclang_path,
                clang_path=clang_resolved,
            )

        if (not libclang_path and clang_path) or \
           (libclang_path and not clang_path):
            die(dedent('''\
            You must provide both of --with-libclang-path and --with-clang-path
            or neither of them.'''))

        libclang_path = libclang_path[0]
        clang_path = clang_path[0]

        if not os.path.exists(libclang_path) or \
           not os.path.isdir(libclang_path):
            die(dedent('''\
            The argument to --with-libclang-path is not a directory: {}
            '''.format(libclang_path)))

        (found, searched) = search_for_libclang(libclang_path)
        if not found:
            die(dedent('''\
            Could not find the clang shared library in the path {}
            specified by --with-libclang-path (searched for files {}).
            '''.format(libclang_path, searched)))

        clang_resolved = find_program(clang_path)
        if not clang_resolved:
            die(dedent('''\
            The argument to --with-clang-path is not a file: {}
            '''.format(clang_path)))

        return namespace(
            libclang_path=libclang_path,
            clang_path=clang_resolved,
        )

    set_config('MOZ_LIBCLANG_PATH', bindgen_config_paths.libclang_path)
    set_config('MOZ_CLANG_PATH', bindgen_config_paths.clang_path)
    set_config('MOZ_STYLO_BINDGEN', depends_if('--enable-stylo-build-bindgen')(lambda _: True))

set_config('MOZ_STYLO', stylo_config.build)
set_define('MOZ_STYLO', stylo_config.build)
set_config('MOZ_STYLO_ENABLE', stylo_config.enable)
set_define('MOZ_STYLO_ENABLE', stylo_config.enable)

option('--with-servo', env='SERVO_TARGET_DIR', nargs=1,
       help='Absolute path of the target directory where libgeckoservo can '
            'be found. This is generally servo_src_dir/target/release.')

@depends_if('--with-servo')
def servo_target_dir(value):
    return value[0]

set_config('SERVO_TARGET_DIR', servo_target_dir)

# WebRender integration
option('--enable-webrender', nargs='?', choices=('build',),
       help='Include WebRender in the build and/or enable it at runtime')

@depends('--enable-webrender', milestone)
def webrender(value, milestone):
    build_webrender = None
    enable_webrender = None

    if value.origin == 'default':
        # if nothing is specified, default to just building on Nightly
        build_webrender = milestone.is_nightly
    elif len(value) and value[0] == 'build':
        # if explicitly set to 'build', then we build but don't enable
        build_webrender = True
    elif bool(value):
        # if set to true, then build and enable
        build_webrender = True
        enable_webrender = True

    # in all other cases, don't build it or enable it (defaults are fine)
    return namespace(
        build = build_webrender,
        enable = enable_webrender,
    )

set_config('MOZ_BUILD_WEBRENDER', webrender.build)
set_define('MOZ_BUILD_WEBRENDER', webrender.build)
set_config('MOZ_ENABLE_WEBRENDER', webrender.enable)

# SIMD acceleration for Rust code (currently just encoding_rs)

option('--enable-rust-simd', env='MOZ_RUST_SIMD',
       help='Enable explicit SIMD in Rust code.')

@depends('--enable-rust-simd', target)
def rust_simd(value, target):
    # As of 2017-06-13, the simd crate only works on aarch64,
    # x86 and x86_64. It's meant to work on 32-bit ARM, too,
    # but currently does not.
    if target.cpu in ('aarch64', 'x86', 'x86_64') and value:
        return True

set_config('MOZ_RUST_SIMD', rust_simd)
set_define('MOZ_RUST_SIMD', rust_simd)

# Printing
# ==============================================================
@depends(target)
def ios_disable_printing(target):
    if target.os == 'iOS':
        return False

imply_option('--enable-printing', ios_disable_printing, reason='--target')

option('--disable-printing', help='Disable printing support')

@depends('--disable-printing')
def printing(value):
    if value:
        return True

set_config('NS_PRINTING', printing)
set_define('NS_PRINTING', printing)
set_define('NS_PRINT_PREVIEW', printing)

# Speech-dispatcher support
# ==============================================================
@depends(toolkit)
def no_speechd_on_non_gtk(toolkit):
    if toolkit not in ('gtk2', 'gtk3'):
        return False

imply_option('--enable-synth-speechd', no_speechd_on_non_gtk,
             reason='--enable-default-toolkit')

option('--disable-synth-speechd', help='Disable speech-dispatcher support')

set_config('MOZ_SYNTH_SPEECHD',
           depends_if('--disable-synth-speechd')(lambda _: True))

# Speech API
# ==============================================================
option('--disable-webspeech', help='Disable support for HTML Speech API')

@depends('--disable-webspeech', '--help')
def webspeech(value, _):
    if value:
        return True

set_config('MOZ_WEBSPEECH', webspeech)
set_define('MOZ_WEBSPEECH', webspeech)
add_old_configure_assignment('MOZ_WEBSPEECH', webspeech)

# Speech API pocketsphinx backend
# ==============================================================
@depends(build_project, milestone, webspeech)
def webspeech_pocketsphinx(build_project, milestone, webspeech):
    if webspeech and milestone.is_nightly and build_project == 'b2g':
        return True

set_config('MOZ_WEBSPEECH_POCKETSPHINX', webspeech_pocketsphinx)
set_define('MOZ_WEBSPEECH_POCKETSPHINX', webspeech_pocketsphinx)

# Speech API models
# ==============================================================
@depends(build_project, milestone, webspeech)
def webspeech_models(build_project, milestone, webspeech):
    if webspeech and milestone.is_nightly and build_project == 'b2g':
        return True

set_config('MOZ_WEBSPEECH_MODELS', webspeech_models)
set_define('MOZ_WEBSPEECH_MODELS', webspeech_models)

# Speech API test backend
# ==============================================================
option('--enable-webspeechtestbackend', default=webspeech,
       help='Enable support for HTML Speech API Test Backend')

@depends_if('--enable-webspeechtestbackend')
def webspeech_test_backend(value):
    return True

set_config('MOZ_WEBSPEECH_TEST_BACKEND', webspeech_test_backend)
set_define('MOZ_WEBSPEECH_TEST_BACKEND', webspeech_test_backend)

# Enable IPDL's "expensive" unit tests
# ==============================================================
option('--enable-ipdl-tests', help='Enable expensive IPDL tests')

set_config('MOZ_IPDL_TESTS',
           depends_if('--enable-ipdl-tests')(lambda _: True))

include('nss.configure')

# Network protocol support
# ==============================================================
@depends(check_build_environment, toolkit_gtk, '--help')
@imports('os')
@imports(_from='__builtin__', _import='sorted')
def all_necko_protocols(build_env, toolkit_gtk, _):
    basedir = os.path.join(build_env.topsrcdir, 'netwerk', 'protocol')
    return tuple(sorted(p for p in os.listdir(basedir)
                        if (os.path.isdir(os.path.join(basedir, p)) and
                            (p != 'gio' or toolkit_gtk))))

default_necko_protocols = all_necko_protocols

@deprecated_option('--enable-necko-protocols', nargs='*')
def necko_protocols(protocols):
    return protocols

@depends(necko_protocols, default_necko_protocols)
def necko_protocols(protocols, default_protocols):
    if protocols is None or (protocols and len(protocols) == 0):
        return None
    if len(protocols) == 1 and protocols[0] == '':
        return False
    result = set()
    for p in protocols:
        if p in ('yes', 'all', 'default'):
            result |= set(default_protocols)
            continue
        if p in ('no', 'none'):
            result = set()
            continue
        if p.startswith('-'):
            if p[1:] in result:
                result.remove(p[1:])
        else:
            result.add(p)
    if result != set(default_protocols):
        return tuple(result)

imply_option('--enable-network-protocols', necko_protocols,
             reason='--enable-necko-protocols')

option('--enable-network-protocols', nargs='+', default=default_necko_protocols,
       choices=all_necko_protocols,
       help='Enable/disable specific protocol handlers')

@depends('--enable-network-protocols')
def necko_protocol_defines(protocols):
    return tuple('NECKO_PROTOCOL_%s' % p for p in protocols)

add_old_configure_assignment('_NON_GLOBAL_ACDEFINES', necko_protocol_defines)

@depends(necko_protocol_defines)
@imports('__sandbox__')
def set_necko_protocol_defines(protocols):
    for p in protocols:
        __sandbox__.set_define_impl(p, True)

@depends('--enable-network-protocols')
@imports(_from='__builtin__', _import='sorted')
def necko_protocols(protocols):
    return tuple(sorted(protocols))

set_config('NECKO_PROTOCOLS', necko_protocols)
add_old_configure_assignment('NECKO_PROTOCOLS', necko_protocols)

# Graphics
# ==============================================================
option('--disable-skia', help='Disable use of Skia')

@depends('--disable-skia')
def skia(value):
    if not value:
        die('--disable-skia is not supported anymore')
    else:
        return True

set_config('MOZ_ENABLE_SKIA', skia)
set_define('MOZ_ENABLE_SKIA', skia)
set_define('USE_SKIA', skia)

@depends(skia, target)
def skia_android(skia, target):
    if skia and target.os == 'Android':
        return True

set_define('SK_BUILD_FOR_ANDROID_NDK', skia_android)

option('--disable-skia-gpu', help='Disable use of Skia-GPU')

@depends('--disable-skia-gpu', skia, target)
def skia_gpu(value, skia, target):
    if value.origin == 'default':
        if not skia:
            return None
        # Skia GPU support may not reliably build on certain *BSDs (see bug 1234494)
        if target.os in ('NetBSD', 'OpenBSD'):
            return None
    elif value and not skia:
        die('Cannot enable Skia-GPU without enabling Skia')
    if skia and value:
        return True

set_config('MOZ_ENABLE_SKIA_GPU', skia_gpu)
set_define('USE_SKIA_GPU', skia_gpu)

option('--enable-skia-pdf', help='Enable Skia PDF')

@depends('--enable-skia-pdf', skia, milestone)
def skia_pdf(value, skia, milestone):
    if value.origin == 'default':
        if not skia:
            return None
        if milestone.is_nightly:
            return True
    elif value and not skia:
        die('Cannot enable Skia PDF without enabling Skia')
    if skia and value:
        return True

set_config('MOZ_ENABLE_SKIA_PDF', skia_pdf)
set_define('MOZ_ENABLE_SKIA_PDF', skia_pdf)

option('--enable-skia-pdf-sfntly', help='Enable SFNTLY font subsetting in Skia PDF')

@depends('--enable-skia-pdf-sfntly', skia_pdf)
def skia_pdf_sfntly(value, skia_pdf):
    if value.origin == 'default':
        return skia_pdf
    if value and not skia_pdf:
        die('Cannot enable SFNTLY subsetting without enabling Skia PDF')
    if skia_pdf and value:
        return True

set_config('MOZ_ENABLE_SKIA_PDF_SFNTLY', skia_pdf_sfntly)
set_define('MOZ_ENABLE_SKIA_PDF_SFNTLY', skia_pdf_sfntly)

@depends(skia_pdf_sfntly)
def sfntly_includes(skia_pdf_sfntly):
    includes = []
    if skia_pdf_sfntly:
        includes += [
            '/gfx/sfntly/cpp/src',
        ]
    return includes

set_config('SFNTLY_INCLUDES', sfntly_includes)

@depends(skia, skia_gpu)
def skia_includes(skia, skia_gpu):
    includes = []
    if skia:
        includes += [
            '/gfx/skia',
            '/gfx/skia/skia/include/config',
            '/gfx/skia/skia/include/core',
        ]

    if skia_gpu:
        includes += [
            '/gfx/skia/skia/include/gpu',
            '/gfx/skia/skia/include/utils',
        ]

    return includes

set_config('SKIA_INCLUDES', skia_includes)

# Build Freetype in the tree
# ==============================================================
@depends(target, skia_pdf)
def tree_freetype(target, skia_pdf):
    if target.os == 'Android' or (skia_pdf and target.os == 'WINNT'):
        return True

set_define('MOZ_TREE_FREETYPE', tree_freetype)
set_config('MOZ_TREE_FREETYPE', tree_freetype)
add_old_configure_assignment('MOZ_TREE_FREETYPE', tree_freetype)

set_define('HAVE_FT_BITMAP_SIZE_Y_PPEM', tree_freetype)
set_define('HAVE_FT_GLYPHSLOT_EMBOLDEN', tree_freetype)
set_define('HAVE_FT_LOAD_SFNT_TABLE', tree_freetype)

@depends(freetype2_combined_info, tree_freetype, check_build_environment)
def ft2_info(freetype2_combined_info, tree_freetype, build_env):
    if tree_freetype:
        return namespace(cflags=('-I%s/modules/freetype2/include' % build_env.topsrcdir,),
                         libs=())
    if freetype2_combined_info:
        return freetype2_combined_info

set_config('FT2_LIBS', ft2_info.libs)
add_old_configure_assignment('FT2_LIBS',
                             ft2_info.libs)
add_old_configure_assignment('FT2_CFLAGS',
                             ft2_info.cflags)

# Mortar
# ==============================================================
option('--enable-mortar', help='Enable mortar extension')

set_config('MOZ_MORTAR', True, when='--enable-mortar')

# Marionette remote protocol
# ==============================================================
#
# Marionette is the Gecko remote protocol used for various remote control,
# automation, and testing purposes throughout Gecko, Firefox, and Fennec.
# Marionette lives in ../testing/marionette.
#
# Marionette is not really a toolkit feature, as much as a Gecko engine
# feature.  But it is enabled based on the toolkit (and target), so here
# it lives.
#
# It also backs ../testing/geckodriver, which is Mozilla's WebDriver
# implementation.
#
# For more information, see
# https://developer.mozilla.org/en-US/docs/Mozilla/QA/Marionette.

@depends(target)
def marionette(target):
    """Enable Marionette by default, except on Android."""
    if target.os != 'Android':
        return True

imply_option('--enable-marionette', marionette, reason='Not Android')

option('--enable-marionette',
       help='Enable Marionette remote protocol')

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

set_config('ENABLE_MARIONETTE', marionette)

# geckodriver WebDriver implementation
# ==============================================================
option('--enable-geckodriver', help='Enable WebDriver implementation')

@depends('--enable-geckodriver',
         'MOZ_AUTOMATION',
         compile_environment,
         cross_compiling,
         hazard_analysis,
         target)
def geckodriver(enable, automation, compile_env, cross_compile, hazard, target):
    """
    geckodriver is implied on supported platforms when MOZ_AUTOMATION
    is set, but we also provide the --enable-geckodriver option for
    developers to use.

    At the present time, we want individual developers to be able to
    opt-in to building geckodriver locally, and for it to be enabled by
    default on supported CI build platforms.
    """
    if enable:
        if not compile_env:
            die("--enable-geckodriver is not available without a compile "
                "environment. A geckodriver binary will be downloaded during "
                "an artifact build by default where available.")
        return True

    if enable.origin == 'default':
        linux32 = target.kernel == 'Linux' and target.cpu == 'x86'
        broken_platforms = cross_compile or linux32 or hazard

        if automation and compile_env and not broken_platforms:
            return True

set_config('ENABLE_GECKODRIVER', geckodriver)

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

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)