setup.py

import atexit
import os.path
import platform
import subprocess
import sys

from setuptools._distutils import sysconfig
from setuptools import Extension, setup

MACOS_FLAG = ['-mmacosx-version-min=10.7']
FLAGS_POSIX = [
    '-fPIC', '-std=gnu++0x', '-Wall', '-Wno-parentheses', '-Werror=switch',
]
FLAGS_CLANG = ['-c', '-O3'] + FLAGS_POSIX + ['-stdlib=libc++']
LFLAGS_POSIX = ['-fPIC',  '-lstdc++']
LFLAGS_CLANG = ['-fPIC', '-stdlib=libc++']

sources = ['_sass.c']
headers = []

if sys.platform == 'win32':
    extra_compile_args = ['/Od', '/EHsc', '/MT']
    extra_link_args = []
elif platform.system() == 'Darwin':
    extra_compile_args = FLAGS_CLANG + MACOS_FLAG
    extra_link_args = LFLAGS_CLANG + MACOS_FLAG
elif platform.system() in {'FreeBSD', 'OpenBSD'}:
    extra_compile_args = FLAGS_CLANG
    extra_link_args = LFLAGS_CLANG
else:
    extra_compile_args = FLAGS_POSIX
    extra_link_args = LFLAGS_POSIX

if platform.system() in {'Darwin', 'FreeBSD', 'OpenBSD'}:
    os.environ.setdefault('CC', 'clang')
    os.environ.setdefault('CXX', 'clang++')
    orig_customize_compiler = sysconfig.customize_compiler

    def customize_compiler(compiler):
        orig_customize_compiler(compiler)
        compiler.compiler[0] = os.environ['CC']
        compiler.compiler_so[0] = os.environ['CXX']
        compiler.compiler_cxx[0] = os.environ['CXX']
        compiler.linker_so[0] = os.environ['CXX']
        return compiler
    sysconfig.customize_compiler = customize_compiler

if os.environ.get('SYSTEM_SASS', False):
    libraries = ['sass']
    include_dirs = []
else:
    LIBSASS_SOURCE_DIR = os.path.join('libsass', 'src')

    if (
            not os.path.isfile(os.path.join('libsass', 'Makefile')) and
            os.path.isdir('.git')
    ):
        print(file=sys.stderr)
        print('Missing the libsass sumbodule.  Try:', file=sys.stderr)
        print('  git submodule update --init', file=sys.stderr)
        print(file=sys.stderr)
        exit(1)

    # Determine the libsass version from the git checkout
    if os.path.exists(os.path.join('libsass', '.git')):
        out = subprocess.check_output((
            'git', '-C', 'libsass', 'describe',
            '--abbrev=4', '--dirty', '--always', '--tags',
        ))
        with open('.libsass-upstream-version', 'wb') as libsass_version_file:
            libsass_version_file.write(out)

    # The version file should always exist at this point
    with open('.libsass-upstream-version', 'rb') as libsass_version_file:
        libsass_version = libsass_version_file.read().decode('UTF-8').strip()
        if sys.platform == 'win32':
            # This looks wrong, but is required for some reason :(
            define = fr'/DLIBSASS_VERSION="\"{libsass_version}\""'
        else:
            define = f'-DLIBSASS_VERSION="{libsass_version}"'

    for directory in (
            os.path.join('libsass', 'src'),
            os.path.join('libsass', 'include'),
    ):
        for pth, _, filenames in os.walk(directory):
            for filename in filenames:
                filename = os.path.join(pth, filename)
                if filename.endswith(('.c', '.cpp')):
                    sources.append(filename)
                elif filename.endswith('.h'):
                    headers.append(filename)

    if platform.system() in {'Darwin', 'FreeBSD', 'OpenBSD'}:
        # Dirty workaround to avoid link error...
        # Python distutils doesn't provide any way
        # to configure different flags for each cc and c++.
        cencode_path = os.path.join(LIBSASS_SOURCE_DIR, 'cencode.c')
        cencode_body = ''
        with open(cencode_path) as f:
            cencode_body = f.read()
        with open(cencode_path, 'w') as f:
            f.write(
                '#ifdef __cplusplus\n'
                'extern "C" {\n'
                '#endif\n',
            )
            f.write(cencode_body)
            f.write(
                '#ifdef __cplusplus\n'
                '}\n'
                '#endif\n',
            )

        @atexit.register
        def restore_cencode():
            if os.path.isfile(cencode_path):
                with open(cencode_path, 'w') as f:
                    f.write(cencode_body)

    libraries = []
    include_dirs = [os.path.join('.', 'libsass', 'include')]
    extra_compile_args.append(define)

sass_extension = Extension(
    '_sass',
    sorted(sources),
    include_dirs=include_dirs,
    depends=headers,
    extra_compile_args=extra_compile_args,
    extra_link_args=extra_link_args,
    libraries=libraries,
    py_limited_api=True,
    define_macros=[('Py_LIMITED_API', None)],
)

cmdclass = {}

try:
    import wheel.bdist_wheel
except ImportError:
    pass
else:
    class bdist_wheel(wheel.bdist_wheel.bdist_wheel):
        def finalize_options(self):
            self.py_limited_api = f'cp3{sys.version_info[1]}'
            super().finalize_options()

    cmdclass['bdist_wheel'] = bdist_wheel


setup(
    name='libsass-bin',
    description='Sass for Python (binary wheels)',
    ext_modules=[sass_extension],
    cmdclass=cmdclass,
)