setup.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import platform
import sysconfig
import tempfile
from distutils.errors import CompileError

from setuptools import setup
from setuptools.extension import Extension
from setuptools.command.build_ext import build_ext
from wheel.bdist_wheel import bdist_wheel

# This fallback is only for jinja, which is used by conda to analyze this setup.py before any build environment
# is set up.
try:
    from Cython.Build import cythonize
except ImportError:
    cythonize = None


withGIL = not sysconfig.get_config_var("Py_GIL_DISABLED")

class bdist_wheel_abi3(bdist_wheel):
    def get_tag(self):
        python, abi, plat = super().get_tag()
        if withGIL and python.startswith("cp"):
            # On CPython, our wheels are abi3 and compatible back to 3.8.
            return "cp38", "abi3", plat
        return python, abi, plat

extensions = [
    Extension(
        # fmt: off
        name               = 'cppbktree',
        sources            = ['cppbktree/cppbktree.pyx'],
        include_dirs       = ['.'],
        language           = 'c++',
        # https://docs.python.org/3/c-api/stable.html#c.Py_LIMITED_API
        # https://docs.python.org/3/c-api/apiabiversion.html#c.Py_Version
        define_macros=[("Py_LIMITED_API", "0x030800f0")] if withGIL else [],
        py_limited_api=withGIL,
        # fmt: on
    ),
]

if cythonize:
    extensions = cythonize(extensions, compiler_directives={'language_level': '3'})


def supportsFlag(compiler, flag):
    with tempfile.NamedTemporaryFile('w', suffix='.cpp') as file:
        file.write('int main() { return 0; }')
        try:
            compiler.compile([file.name], extra_postargs=[flag])
        except CompileError:
            print("[Info] Compiling with argument failed. Will try another one. The above error can be ignored!")
            return False
    return True


def hasInclude(compiler, systemInclude):
    with tempfile.NamedTemporaryFile('w', suffix='.cpp') as file:
        file.write(f'#include <{systemInclude}>\n' + 'int main() { return 0; }')
        try:
            compiler.compile([file.name])
        except CompileError:
            print(
                f"[Info] Check for {systemInclude} system header failed. Will try without out it. "
                "The above error can be ignored!"
            )
            return False
    return True


# https://github.com/cython/cython/blob/master/docs/src/tutorial/appendix.rst#python-38
class Build(build_ext):
    def build_extensions(self):
        # This is as hacky as it gets just in order to have different compile arguments for the zlib C-code as
        # opposed to the C++ code but I don't see another way with this subpar "build system" if you can call
        # it even that.
        oldCompile = self.compiler.compile

        def newCompile(sources, *args, **kwargs):
            cSources = [source for source in sources if source.endswith('.c')]
            cppSources = [source for source in sources if not source.endswith('.c')]

            objects = oldCompile(cppSources, *args, **kwargs)
            cppCompileArgs = [
                '-std=c++17',
                '/std:c++17',
            ]
            if 'extra_postargs' in kwargs:
                kwargs['extra_postargs'] = [x for x in kwargs['extra_postargs'] if x not in cppCompileArgs]
            cppObjects = oldCompile(cSources, *args, **kwargs)
            objects.extend(cppObjects)
            return objects

        self.compiler.compile = newCompile

        for ext in self.extensions:
            ext.extra_compile_args = ['-std=c++17', '-O3', '-DNDEBUG']

            # SSE 4.2 is important for the popcnt instruction to be used for a 3x speedup using the linear lookup.
            # SSE 4.2 has been available on all x86 processors since 2011.
            if supportsFlag(self.compiler, '-msse4.2'):
                ext.extra_compile_args += ['-msse4.2']

            # https://github.com/cython/cython/issues/2670#issuecomment-432212671
            # https://github.com/cython/cython/issues/3405#issuecomment-596975159
            # https://bugs.python.org/issue35037
            # https://bugs.python.org/issue4709
            if platform.system() == 'Windows' and platform.machine().endswith('64'):
                ext.extra_compile_args += ['-DMS_WIN64']

            if self.compiler.compiler_type == 'mingw32':
                ext.extra_link_args = [
                    '-static-libgcc',
                    '-static-libstdc++',
                ]

            elif self.compiler.compiler_type == 'msvc':
                ext.extra_compile_args = [
                    '/std:c++17',
                    '/O2',
                    '/DNDEBUG',
                ]

            if hasInclude(self.compiler, 'unistd.h'):
                ext.extra_compile_args += ['-DZ_HAVE_UNISTD_H']

        super(Build, self).build_extensions()


setup(
    # fmt: off
    ext_modules = extensions,
    cmdclass    = {'build_ext': Build, "bdist_wheel": bdist_wheel_abi3},
    # fmt: on
)