swift-mirror/utils/build-script

#!/usr/bin/env python3

# This source file is part of the Swift.org open source project
#
# Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
# Licensed under Apache License v2.0 with Runtime Library Exception
#
# See https://swift.org/LICENSE.txt for license information
# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors


"""
The ultimate tool for building Swift.
"""


from argparse import Namespace
import json
import os
import platform
import re
import sys
import time

from build_swift.build_swift import argparse
from build_swift.build_swift import defaults
from build_swift.build_swift import driver_arguments
from build_swift.build_swift import migration
from build_swift.build_swift import presets
from build_swift.build_swift.constants import BUILD_SCRIPT_IMPL_PATH
from build_swift.build_swift.constants import SWIFT_BUILD_ROOT
from build_swift.build_swift.constants import SWIFT_REPO_NAME
from build_swift.build_swift.constants import SWIFT_SOURCE_ROOT

from swift_build_support.swift_build_support import build_script_invocation
from swift_build_support.swift_build_support import shell
from swift_build_support.swift_build_support import targets
from swift_build_support.swift_build_support import workspace
from swift_build_support.swift_build_support.cmake import CMake
from swift_build_support.swift_build_support.targets import StdlibDeploymentTarget
from swift_build_support.swift_build_support.toolchain import host_toolchain
from swift_build_support.swift_build_support.utils \
    import exit_rejecting_arguments
from swift_build_support.swift_build_support.utils import fatal_error
from swift_build_support.swift_build_support.utils import log_analyzer


# -----------------------------------------------------------------------------
# Helpers


def print_note(message, stream=sys.stdout):
    """Writes a diagnostic message to the given stream. By default this
    function outputs to stdout.
    """

    stream.write('[{}] NOTE: {}\n'.format(sys.argv[0], message))
    stream.flush()


def print_warning(message, stream=sys.stdout):
    """Writes a warning to the given stream. By default this function outputs
    to stdout.
    """

    warning = "[{}] WARNING: {}\n".format(sys.argv[0], message)
    magenta_warning = "\033[35m" + warning + "\033[0m"

    stream.write(magenta_warning)
    stream.flush()


def clean_delay():
    """Provide a short delay so accidentally invoked clean builds can be
    canceled.
    """

    sys.stdout.write('Starting clean build in  ')
    for i in range(3, 0, -1):
        sys.stdout.write('\b%d' % i)
        sys.stdout.flush()
        time.sleep(1)
    print('\b\b\b\bnow.')


def initialize_runtime_environment():
    """Change the program environment for building.
    """

    # Set an appropriate default umask.
    os.umask(0o022)

    # Unset environment variables that might affect how tools behave.
    for v in [
            'MAKEFLAGS',
            'SDKROOT',
            'MACOSX_DEPLOYMENT_TARGET',
            'IPHONEOS_DEPLOYMENT_TARGET',
            'TVOS_DEPLOYMENT_TARGET',
            'WATCHOS_DEPLOYMENT_TARGET',
            'XROS_DEPLOYMENT_TARGET']:
        os.environ.pop(v, None)

    # Provide a default NINJA_STATUS to format ninja output.
    if 'NINJA_STATUS' not in os.environ:
        os.environ['NINJA_STATUS'] = '[%f/%t][%p][%es] '


class JSONDumper(json.JSONEncoder):
    def __init__(self, *args, **kwargs):
        json.JSONEncoder.__init__(
            self, indent=2, separators=(',', ': '), sort_keys=True,
            *args, **kwargs)

    def default(self, o):
        if hasattr(o, '__dict__'):
            return vars(o)
        return str(o)


def print_xcodebuild_versions(file=sys.stdout):
    """
    Print the host machine's `xcodebuild` version, as well as version
    information for all available SDKs.
    """
    version = shell.capture(
        ['xcodebuild', '-version'], dry_run=False, echo=False).rstrip()
    # Allow non-zero exit codes.  Under certain obscure circumstances
    # xcodebuild can exit with a non-zero exit code even when the SDK is
    # usable.
    sdks = shell.capture(
        ['xcodebuild', '-version', '-sdk'], dry_run=False, echo=False,
        allow_non_zero_exit=True).rstrip()
    fmt = '{version}\n\n--- SDK versions ---\n{sdks}\n'

    print(fmt.format(version=version, sdks=sdks), file=file)
    file.flush()


def validate_xcode_compatibility():
    if sys.platform != 'darwin':
        return

    if os.getenv("SKIP_XCODE_VERSION_CHECK"):
        print("note: skipping Xcode version check")
        return

    output = shell.capture(
        ['xcodebuild', '-version'], dry_run=False, echo=False).strip()
    # Capture only version ex: '14.x' from full output
    match = re.match(r"Xcode (\d+\.\d+(?:\.\d)?)", output)
    if not match:
        print(f"warning: unexpected xcodebuild output format: '{output}', "
              "skipping Xcode compatibility check, please report this issue",
              file=sys.stderr)
        return

    version_match = match.group(1)
    current_version = tuple(int(v) for v in version_match.replace('.', ' ').split())
    minimum_version = (13, 0)
    if current_version < minimum_version:
        raise SystemExit(
            f"error: using unsupported Xcode version '{version_match}'. "
            f"Install Xcode {'.'.join(str(x) for x in minimum_version)} or newer, "
            "or set 'SKIP_XCODE_VERSION_CHECK=1' in the environment"
        )


def tar(source, destination):
    """
    Create a gzip archive of the file at 'source' at the given
    'destination' path.
    """
    # We do not use `tarfile` here because:
    #  - We wish to support LZMA2 compression while also supporting Python 2.7.
    #  - We wish to explicitly set the owner and group of the archive.
    args = ['tar', '-c', '-z', '-f', destination]

    if platform.system() != 'Darwin' and platform.system() != 'Windows':
        args += ['--owner=0', '--group=0']

    # Discard stderr output such as 'tar: Failed to open ...'. We'll detect
    # these cases using the exit code, which should cause 'shell.call' to
    # raise.
    shell.call(args + [source], stderr=shell.DEVNULL)


# -----------------------------------------------------------------------------
# Argument Validation

def validate_arguments(toolchain, args: Namespace):
    if toolchain.cc is None or toolchain.cxx is None:
        fatal_error(
            "can't find clang (please install clang-3.5 or a "
            "later version)")

    if toolchain.cmake is None:
        fatal_error("can't find CMake (please install CMake)")

    if args.distcc:
        if toolchain.distcc is None:
            fatal_error(
                "can't find distcc (please install distcc)")
        if toolchain.distcc_pump is None:
            fatal_error(
                "can't find distcc-pump (please install distcc-pump)")

    if args.sccache:
        if toolchain.sccache is None:
            fatal_error(
                "can't find sccache (please install sccache)")

    # Xcode project generation is no longer supported.
    if args.cmake_generator == "Xcode":
        fatal_error(
            "build-script no longer supports Xcode project generation, you "
            "should use utils/generate-xcode instead, see "
            "https://github.com/swiftlang/swift/blob/main/docs/HowToGuides/"
            "GettingStarted.md#using-ninja-with-xcode for more info"
        )

    if args.host_target is None or args.stdlib_deployment_targets is None:
        fatal_error("unknown operating system")

    if args.symbols_package:
        if not os.path.isabs(args.symbols_package):
            print(
                '--symbols-package must be an absolute path '
                '(was \'{}\')'.format(args.symbols_package))
            return 1
        if not args.install_symroot:
            fatal_error(
                "--install-symroot is required when specifying "
                "--symbols-package.")

    if args.android:
        if args.android_ndk is None or \
                args.android_api_level is None:
            fatal_error(
                "when building for Android, --android-ndk "
                "and --android-api-level must be specified")

    targets_needing_toolchain = [
        'build_indexstoredb',
        'build_playgroundsupport',
        'build_sourcekitlsp',
        'build_toolchainbenchmarks',
        'build_swift_inspect',
        'tsan_libdispatch_test',
    ]
    has_target_needing_toolchain = \
        bool(sum(getattr(args, x) for x in targets_needing_toolchain))
    if args.legacy_impl and has_target_needing_toolchain:
        fatal_error(
            "--legacy-impl is incompatible with building packages needing "
            "a toolchain (%s)" % ", ".join(targets_needing_toolchain))


def default_stdlib_deployment_targets(args):
    """
    Return targets for the Swift stdlib, based on the build machine.
    If the build machine is not one of the recognized ones, return None.
    """

    host_target = StdlibDeploymentTarget.host_target()
    if host_target is None:
        return None

    targets = [host_target]

    # OS X build machines configure all Darwin platforms by default.
    # Put iOS native targets last so that we test them last
    # (it takes a long time).
    if host_target == StdlibDeploymentTarget.OSX.x86_64 or \
            host_target == StdlibDeploymentTarget.OSX.arm64:
        if args.build_ios and args.build_ios_simulator:
            targets.extend(StdlibDeploymentTarget.iOSSimulator.targets)
        if args.build_ios and args.build_ios_device:
            targets.extend(StdlibDeploymentTarget.iOS.targets)
        if args.build_tvos and args.build_tvos_simulator:
            targets.extend(StdlibDeploymentTarget.AppleTVSimulator.targets)
        if args.build_tvos and args.build_tvos_device:
            targets.extend(StdlibDeploymentTarget.AppleTV.targets)
        if args.build_watchos and args.build_watchos_simulator:
            targets.extend(StdlibDeploymentTarget
                           .AppleWatchSimulator.targets)
        if args.build_watchos and args.build_watchos_device:
            targets.extend(StdlibDeploymentTarget.AppleWatch.targets)
        if StdlibDeploymentTarget.XROSSimulator and \
           args.build_xros and args.build_xros_simulator:
            targets.extend(StdlibDeploymentTarget.XROSSimulator.targets)
        if StdlibDeploymentTarget.XROS and \
           args.build_xros and args.build_xros_device:
            targets.extend(StdlibDeploymentTarget.XROS.targets)
        return targets
    elif host_target.platform.name == 'linux':
        if args.build_linux_static:
            targets.append(getattr(StdlibDeploymentTarget.Musl,
                                   host_target.arch))

    return targets


def apply_default_arguments(toolchain, args):
    # Infer if ninja is required
    ninja_required = (
        args.build_foundation or
        args.build_indexstoredb or
        args.build_sourcekitlsp or
        args.cmake_generator == 'Ninja'
    )
    if ninja_required and toolchain.ninja is None:
        args.build_ninja = True

    # Enable test colors if we're on a tty.
    if args.color_in_tests and sys.stdout.isatty():
        args.lit_args += " --param color_output"

    # Set the default stdlib-deployment-targets, if none were provided.
    if args.stdlib_deployment_targets is None:
        stdlib_targets = default_stdlib_deployment_targets(args)
        args.stdlib_deployment_targets = [
            target.name for target in stdlib_targets]

    # SwiftPM and XCTest have a dependency on Foundation.
    # On OS X, Foundation is built automatically using xcodebuild.
    # On Linux, we must ensure that it is built manually.
    if ((args.build_swiftpm or args.build_xctest) and
            platform.system() != "Darwin"):
        args.build_foundation = True

    # Foundation has a dependency on libdispatch.
    # On OS X, libdispatch is provided by the OS.
    # On Linux, we must ensure that it is built manually.
    if (args.build_foundation and
            platform.system() != "Darwin"):
        args.build_libdispatch = True

    if args.build_subdir is None:
        args.build_subdir = \
            workspace.compute_build_subdir(args)

    if args.relocate_xdg_cache_home_under_build_subdir:
        cache_under_build_subdir = os.path.join(
            SWIFT_BUILD_ROOT, args.build_subdir, '.cache')
        if args.verbose_build:
            print("Relocating XDG_CACHE_HOME to {}".format(cache_under_build_subdir))
        workspace.relocate_xdg_cache_home_under(cache_under_build_subdir)

    if args.install_destdir is None:
        args.install_destdir = os.path.join(
            SWIFT_BUILD_ROOT, args.build_subdir,
            '{}-{}'.format('toolchain', args.host_target))

    # Add optional stdlib-deployment-targets
    if args.android:
        if args.android_arch == "armv7":
            args.stdlib_deployment_targets.append(
                StdlibDeploymentTarget.Android.armv7.name)
        elif args.android_arch == "aarch64":
            args.stdlib_deployment_targets.append(
                StdlibDeploymentTarget.Android.aarch64.name)
        elif args.android_arch == "x86_64":
            args.stdlib_deployment_targets.append(
                StdlibDeploymentTarget.Android.x86_64.name)

    # Infer platform flags from manually-specified configure targets.
    # This doesn't apply to Darwin platforms, as they are
    # already configured. No building without the platform flag, though.

    android_tgts = [tgt for tgt in args.stdlib_deployment_targets
                    if StdlibDeploymentTarget.Android.contains(tgt)]
    if not args.android and len(android_tgts) > 0:
        # If building natively on an Android host, avoid the NDK
        # cross-compilation configuration.
        if not StdlibDeploymentTarget.Android.contains(StdlibDeploymentTarget
                                                       .host_target().name):
            args.android = True
        args.build_android = False

    # Include the Darwin supported architectures in the CMake options.
    if args.swift_darwin_supported_archs:
        args.extra_cmake_options.append(
            '-DSWIFT_DARWIN_SUPPORTED_ARCHS:STRING={}'.format(
                args.swift_darwin_supported_archs))

        # Remove unsupported Darwin archs from the standard library
        # deployment targets.
        supported_archs = args.swift_darwin_supported_archs.split(';')
        targets = StdlibDeploymentTarget.get_targets_by_name(
            args.stdlib_deployment_targets)

        args.stdlib_deployment_targets = [
            target.name
            for target in targets
            if (target.platform.is_darwin and
                target.arch in supported_archs)
        ]
    else:
        # Clear the value explicitly from CMakeCache.txt
        # to avoid picking up a stale value that can cause
        # build failures
        args.extra_cmake_options.append(
            '-USWIFT_DARWIN_SUPPORTED_ARCHS')

    # Filter out any macOS stdlib deployment targets that are not supported
    # by the macOS SDK.
    targets = StdlibDeploymentTarget.get_targets_by_name(
        args.stdlib_deployment_targets)
    args.stdlib_deployment_targets = [
        target.name
        for target in targets
        if (not target.platform.is_darwin or
            target.platform.sdk_supports_architecture(
                target.arch, args.darwin_xcrun_toolchain, args))
    ]

    # Include the Darwin module-only architectures in the CMake options.
    if args.swift_darwin_module_archs:
        args.extra_cmake_options.append(
            '-DSWIFT_DARWIN_MODULE_ARCHS:STRING={}'.format(
                args.swift_darwin_module_archs))
    if (args.infer_cross_compile_hosts_on_darwin and
            platform.system() == "Darwin"):
        args.cross_compile_hosts = _infer_cross_compile_hosts_on_darwin(
            get_running_arch(args.dry_run))
        print("Inferred the following hosts for cross compilations: "
              f"{args.cross_compile_hosts}")
        sys.stdout.flush()


def _infer_cross_compile_hosts_on_darwin(arch_we_are_running_on):
    if arch_we_are_running_on == "x86_64":
        return ["macosx-arm64"]
    else:
        return ["macosx-x86_64"]


def get_running_arch(dry_run):
    # We can override the detected arch to support
    # BuildSystem/infer-cross-compile-hosts-on-darwin-macosx.test
    # Given the narrow scenario, we preferred using
    # an environment variable instead of a build-script
    # argument to make this less discoverable on purpose
    if dry_run:
        injected_arch = os.environ.get(
            'ARCH_FOR_BUILDSYSTEM_TESTS',
            platform.machine())
        print("DRY RUN: assume build-script is being run on a "
              f"{injected_arch} machine")
        return injected_arch
    else:
        return platform.machine()


# -----------------------------------------------------------------------------
# Main (preset)


def parse_preset_args():
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description="""Builds Swift using a preset.""")
    parser.add_argument(
        "-n", "--dry-run",
        help="print the commands that would be executed, but do not execute "
             "them",
        action="store_true",
        default=False)
    parser.add_argument(
        "--preset-file",
        help="load presets from the specified file",
        metavar="PATH",
        action="append",
        dest="preset_file_names",
        default=[])
    parser.add_argument(
        "--preset",
        help="use the specified option preset",
        metavar="NAME")
    parser.add_argument(
        "--show-presets",
        help="list all presets and exit",
        action=argparse.actions.StoreTrueAction,
        nargs=argparse.Nargs.OPTIONAL)
    parser.add_argument(
        "--preset-vars-file",
        help="load preset vars from the specified file",
        metavar="PATH",
        action="append",
        dest="preset_vars_file_names",
        default=[])
    parser.add_argument(
        "--distcc",
        help="use distcc",
        action=argparse.actions.StoreTrueAction,
        nargs=argparse.Nargs.OPTIONAL,
        default=os.environ.get('USE_DISTCC') == '1')
    parser.add_argument(
        "--sccache",
        help="use sccache",
        action=argparse.actions.StoreTrueAction,
        nargs=argparse.Nargs.OPTIONAL,
        default=os.environ.get('SWIFT_USE_SCCACHE') == '1')
    parser.add_argument(
        "--cmake-c-launcher",
        help="the absolute path to set CMAKE_C_COMPILER_LAUNCHER",
        metavar="PATH")
    parser.add_argument(
        "--cmake-cxx-launcher",
        help="the absolute path to set CMAKE_CXX_COMPILER_LAUNCHER",
        metavar="PATH")
    parser.add_argument(
        "-j", "--jobs",
        help="the number of parallel build jobs to use",
        type=int,
        dest="build_jobs")
    parser.add_argument(
        "--lit-jobs",
        help="the number of workers to use when testing with lit",
        type=int,
        dest="lit_jobs")
    parser.add_argument(
        "preset_substitutions_raw",
        help="'name=value' pairs that are substituted in the preset",
        nargs="*",
        metavar="SUBSTITUTION")
    parser.add_argument(
        "--expand-invocation", "--expand-build-script-invocation",
        help="Print the expanded build-script invocation generated "
             "by the preset, but do not run the preset",
        action=argparse.actions.StoreTrueAction,
        nargs=argparse.Nargs.OPTIONAL)
    parser.add_argument(
        "--swiftsyntax-install-prefix",
        help="specify the directory to where SwiftSyntax should be installed")
    parser.add_argument(
        "--build-dir",
        help="specify the directory where build artifact should be stored")
    parser.add_argument(
        "--dump-config",
        help="instead of building, write JSON to stdout containing "
             "various values used to build in this configuration",
        action="store_true",
        default=False)
    parser.add_argument(
        "--reconfigure",
        help="Reconfigure all projects as we build",
        action="store_true",
        default=False)

    return parser.parse_args()


def main_preset():
    args = parse_preset_args()

    if len(args.preset_file_names) == 0:
        args.preset_file_names = [
            os.path.join(
                SWIFT_SOURCE_ROOT, SWIFT_REPO_NAME, "utils",
                "build-presets.ini")
        ]

        user_presets_file = os.path.join(os.path.expanduser("~"),
                                         '.swift-build-presets')
        if os.path.isfile(user_presets_file):
            args.preset_file_names.append(user_presets_file)

    preset_parser = presets.PresetParser()

    try:
        preset_parser.read_files(args.preset_file_names)
    except presets.PresetError as e:
        fatal_error(str(e))

    if args.show_presets:
        for name in sorted(preset_parser.preset_names,
                           key=lambda name: name.lower()):
            print(name)
        return 0

    if not args.preset:
        fatal_error("missing --preset option")

    args.preset_substitutions = {}
    for file in args.preset_vars_file_names:
        if os.path.isfile(file):
            with open(file, 'r') as f:
                for _, line in enumerate(f):
                    name, value = line.split("=", 1)
                    args.preset_substitutions[name] = value.strip()

    for arg in args.preset_substitutions_raw:
        name, value = arg.split("=", 1)
        args.preset_substitutions[name] = value

    try:
        preset = preset_parser.get_preset(
            args.preset,
            vars=args.preset_substitutions)
    except presets.PresetError as e:
        fatal_error(str(e))

    preset_args = migration.migrate_swift_sdks(preset.args)

    if args.distcc and (args.cmake_c_launcher or args.cmake_cxx_launcher):
        fatal_error(
            '--distcc can not be used with' +
            ' --cmake-c-launcher or --cmake-cxx-launcher')
    if args.sccache and (args.cmake_c_launcher or args.cmake_cxx_launcher):
        fatal_error(
            '--sccache can not be used with' +
            ' --cmake-c-launcher or --cmake-cxx-launcher')

    build_script_args = [sys.argv[0]]
    if args.dry_run:
        build_script_args += ["--dry-run"]
    if args.dump_config:
        build_script_args += ["--dump-config"]

    build_script_args += preset_args
    if args.distcc:
        build_script_args += ["--distcc"]
    if args.sccache:
        build_script_args += ["--sccache"]
    if args.build_jobs:
        build_script_args += ["--jobs", str(args.build_jobs)]
    if args.lit_jobs:
        build_script_args += ["--lit-jobs", str(args.lit_jobs)]
    if args.swiftsyntax_install_prefix:
        build_script_args += ["--install-swiftsyntax",
                              "--install-destdir",
                              args.swiftsyntax_install_prefix]
    if args.build_dir:
        build_script_args += ["--build-dir", args.build_dir]
    if args.cmake_c_launcher:
        build_script_args += ["--cmake-c-launcher", args.cmake_c_launcher]
    if args.cmake_cxx_launcher:
        build_script_args += ["--cmake-cxx-launcher", args.cmake_cxx_launcher]
    printable_command = shell.quote_command(build_script_args)
    if args.expand_invocation:
        print(printable_command)
        return 0

    if args.reconfigure:
        build_script_args += ["--reconfigure"]

    print_note('using preset "{}", which expands to \n\n{}\n'.format(
        args.preset, printable_command))
    shell.call_without_sleeping(build_script_args)
    return 0


# -----------------------------------------------------------------------------
# Main (normal)

def main_normal():
    parser = driver_arguments.create_argument_parser()

    args = migration.parse_args(parser, sys.argv[1:])

    if args.build_script_impl_args:
        # If we received any impl args, check if `build-script-impl` would
        # accept them or not before any further processing.
        try:
            migration.check_impl_args(BUILD_SCRIPT_IMPL_PATH,
                                      args.build_script_impl_args)
        except ValueError as e:
            exit_rejecting_arguments(e, parser)

        if '--check-args-only' in args.build_script_impl_args:
            return 0

    shell.dry_run = args.dry_run

    # Prepare and validate toolchain
    if args.darwin_xcrun_toolchain is None:
        xcrun_toolchain = os.environ.get('TOOLCHAINS',
                                         defaults.DARWIN_XCRUN_TOOLCHAIN)

        print_note('Using toolchain {}'.format(xcrun_toolchain))
        args.darwin_xcrun_toolchain = xcrun_toolchain

    toolchain = host_toolchain(xcrun_toolchain=args.darwin_xcrun_toolchain)
    os.environ['TOOLCHAINS'] = args.darwin_xcrun_toolchain

    if args.host_cc is not None:
        toolchain.cc = args.host_cc
    if args.host_cxx is not None:
        toolchain.cxx = args.host_cxx
    if args.host_lipo is not None:
        toolchain.lipo = args.host_lipo
    if args.host_libtool is not None:
        toolchain.libtool = args.host_libtool
    if args.cmake is not None:
        toolchain.cmake = args.cmake

    # Preprocess the arguments to apply defaults.
    apply_default_arguments(toolchain, args)

    cmake = CMake(args=args, toolchain=toolchain)
    toolchain.cmake = cmake.get_cmake_path(source_root=SWIFT_SOURCE_ROOT,
                                           build_root=SWIFT_BUILD_ROOT)
    args.cmake = toolchain.cmake

    # Create the build script invocation.
    invocation = build_script_invocation.BuildScriptInvocation(toolchain, args)

    # Validate the arguments.
    validate_arguments(toolchain, args)

    if args.sccache:
        print("Ensuring the sccache server is running...")
        # Use --show-stats to ensure the server is started, because using
        # --start-server will fail if the server is already running.
        # Capture the output because we don't want to see the stats.
        shell.capture([toolchain.sccache, "--show-stats"])

    # Sanitize the runtime environment.
    initialize_runtime_environment()

    # Show SDKs, if requested.
    if args.show_sdks:
        print_xcodebuild_versions()

    if args.dump_config:
        print(JSONDumper().encode(invocation))
        return 0

    # Clean build directory if requested.
    if args.clean:
        clean_delay()
        shell.rmtree(invocation.workspace.build_root)

    # Create build directory.
    shell.makedirs(invocation.workspace.build_root)

    # Create .build_script_log
    if not args.dry_run:
        build_script_log = os.path.join(invocation.workspace.build_root,
                                        ".build_script_log")
        open(build_script_log, 'w').close()

    if args.clean_install_destdir:
        sys.stdout.write("Cleaning install destdir!\n")
        shell.rmtree(args.install_destdir)

    # Execute the underlying build script implementation.
    invocation.execute()

    if args.symbols_package:
        print('--- Creating symbols package ---')
        print('-- Package file: {} --'.format(args.symbols_package))

        if platform.system() == 'Darwin':
            prefix = targets.darwin_toolchain_prefix(args.install_prefix)
            prefix = os.path.join(args.host_target, prefix.lstrip('/'))
        else:
            prefix = args.install_prefix

        # As a security measure, `tar` normally strips leading '/' from paths
        # it is archiving. To stay safe, we change working directories, then
        # run `tar` without the leading '/' (we remove it ourselves to keep
        # `tar` from emitting a warning).
        with shell.pushd(args.install_symroot):
            tar(source=prefix.lstrip('/'),
                destination=args.symbols_package)

    return 0


# -----------------------------------------------------------------------------

def main():
    if not SWIFT_SOURCE_ROOT:
        fatal_error(
            "could not infer source root directory " +
            "(forgot to set $SWIFT_SOURCE_ROOT environment variable?)")

    if not os.path.isdir(SWIFT_SOURCE_ROOT):
        fatal_error(
            "source root directory \'" + SWIFT_SOURCE_ROOT +
            "\' does not exist " +
            "(forgot to set $SWIFT_SOURCE_ROOT environment variable?)")

    validate_xcode_compatibility()

    # Determine if we are invoked in the preset mode and dispatch accordingly.
    if any([(opt.startswith("--preset") or opt == "--show-presets")
            for opt in sys.argv[1:]]):
        return main_preset()
    else:
        return main_normal()


if __name__ == "__main__":
    try:
        exit_code = main()
        log_analyzer()
    except SystemExit:
        raise
    except KeyboardInterrupt:
        sys.exit(1)
    except Exception:
        log_analyzer()
        raise
    sys.exit(exit_code)