gh-116869: Add test_cext test: build a C extension (#116954)

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Victor Stinner 2024-03-18 20:15:20 +01:00 committed by GitHub
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# gh-116869: Build a basic C test extension to check that the Python C API
# does not emit C compiler warnings.
import os.path
import shutil
import subprocess
import sysconfig
import unittest
from test import support
SOURCE = os.path.join(os.path.dirname(__file__), 'extension.c')
SETUP = os.path.join(os.path.dirname(__file__), 'setup.py')
# gh-110119: pip does not currently support 't' in the ABI flag use by
# --disable-gil builds. Once it does, we can remove this skip.
@unittest.skipIf(support.Py_GIL_DISABLED,
'test does not work with --disable-gil')
@support.requires_subprocess()
@support.requires_resource('cpu')
class TestExt(unittest.TestCase):
def test_build_c99(self):
self.check_build('c99', '_test_c99_ext')
def test_build_c11(self):
self.check_build('c11', '_test_c11_ext')
# With MSVC, the linker fails with: cannot open file 'python311.lib'
# https://github.com/python/cpython/pull/32175#issuecomment-1111175897
@unittest.skipIf(support.MS_WINDOWS, 'test fails on Windows')
# Building and running an extension in clang sanitizing mode is not
# straightforward
@unittest.skipIf(
'-fsanitize' in (sysconfig.get_config_var('PY_CFLAGS') or ''),
'test does not work with analyzing builds')
# the test uses venv+pip: skip if it's not available
@support.requires_venv_with_pip()
def check_build(self, clang_std, extension_name):
venv_dir = 'env'
with support.setup_venv_with_pip_setuptools_wheel(venv_dir) as python_exe:
self._check_build(clang_std, extension_name, python_exe)
def _check_build(self, clang_std, extension_name, python_exe):
pkg_dir = 'pkg'
os.mkdir(pkg_dir)
shutil.copy(SETUP, os.path.join(pkg_dir, os.path.basename(SETUP)))
shutil.copy(SOURCE, os.path.join(pkg_dir, os.path.basename(SOURCE)))
def run_cmd(operation, cmd):
env = os.environ.copy()
env['CPYTHON_TEST_STD'] = clang_std
env['CPYTHON_TEST_EXT_NAME'] = extension_name
if support.verbose:
print('Run:', ' '.join(cmd))
subprocess.run(cmd, check=True, env=env)
else:
proc = subprocess.run(cmd,
env=env,
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
text=True)
if proc.returncode:
print(proc.stdout, end='')
self.fail(
f"{operation} failed with exit code {proc.returncode}")
# Build and install the C extension
cmd = [python_exe, '-X', 'dev',
'-m', 'pip', 'install', '--no-build-isolation',
os.path.abspath(pkg_dir)]
run_cmd('Install', cmd)
# Do a reference run. Until we test that running python
# doesn't leak references (gh-94755), run it so one can manually check
# -X showrefcount results against this baseline.
cmd = [python_exe,
'-X', 'dev',
'-X', 'showrefcount',
'-c', 'pass']
run_cmd('Reference run', cmd)
# Import the C extension
cmd = [python_exe,
'-X', 'dev',
'-X', 'showrefcount',
'-c', f"import {extension_name}"]
run_cmd('Import', cmd)
if __name__ == "__main__":
unittest.main()

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// gh-116869: Basic C test extension to check that the Python C API
// does not emit C compiler warnings.
// Always enable assertions
#undef NDEBUG
#include "Python.h"
#if defined (__STDC_VERSION__) && __STDC_VERSION__ > 201710L
# define NAME _test_c2x_ext
#elif defined (__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
# define NAME _test_c11_ext
#else
# define NAME _test_c99_ext
#endif
#define _STR(NAME) #NAME
#define STR(NAME) _STR(NAME)
PyDoc_STRVAR(_testcext_add_doc,
"add(x, y)\n"
"\n"
"Return the sum of two integers: x + y.");
static PyObject *
_testcext_add(PyObject *Py_UNUSED(module), PyObject *args)
{
long i, j;
if (!PyArg_ParseTuple(args, "ll:foo", &i, &j)) {
return NULL;
}
long res = i + j;
return PyLong_FromLong(res);
}
static PyMethodDef _testcext_methods[] = {
{"add", _testcext_add, METH_VARARGS, _testcext_add_doc},
{NULL, NULL, 0, NULL} // sentinel
};
static int
_testcext_exec(PyObject *module)
{
if (PyModule_AddIntMacro(module, __STDC_VERSION__) < 0) {
return -1;
}
return 0;
}
static PyModuleDef_Slot _testcext_slots[] = {
{Py_mod_exec, _testcext_exec},
{0, NULL}
};
PyDoc_STRVAR(_testcext_doc, "C test extension.");
static struct PyModuleDef _testcext_module = {
PyModuleDef_HEAD_INIT, // m_base
STR(NAME), // m_name
_testcext_doc, // m_doc
0, // m_size
_testcext_methods, // m_methods
_testcext_slots, // m_slots
NULL, // m_traverse
NULL, // m_clear
NULL, // m_free
};
#define _FUNC_NAME(NAME) PyInit_ ## NAME
#define FUNC_NAME(NAME) _FUNC_NAME(NAME)
PyMODINIT_FUNC
FUNC_NAME(NAME)(void)
{
return PyModuleDef_Init(&_testcext_module);
}

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# gh-91321: Build a basic C test extension to check that the Python C API is
# compatible with C and does not emit C compiler warnings.
import os
import shlex
import sys
import sysconfig
from test import support
from setuptools import setup, Extension
SOURCE = 'extension.c'
if not support.MS_WINDOWS:
# C compiler flags for GCC and clang
CFLAGS = [
# The purpose of test_cext extension is to check that building a C
# extension using the Python C API does not emit C compiler warnings.
'-Werror',
]
else:
# Don't pass any compiler flag to MSVC
CFLAGS = []
def main():
std = os.environ["CPYTHON_TEST_STD"]
name = os.environ["CPYTHON_TEST_EXT_NAME"]
cflags = [*CFLAGS, f'-std={std}']
# Remove existing -std options to only test ours
cmd = (sysconfig.get_config_var('CC') or '')
if cmd is not None:
cmd = shlex.split(cmd)
cmd = [arg for arg in cmd if not arg.startswith('-std=')]
cmd = shlex.join(cmd)
# CC env var overrides sysconfig CC variable in setuptools
os.environ['CC'] = cmd
ext = Extension(
name,
sources=[SOURCE],
extra_compile_args=cflags)
setup(name='internal' + name, version='0.0', ext_modules=[ext])
if __name__ == "__main__":
main()

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@ -2330,6 +2330,7 @@ TESTSUBDIRS= idlelib/idle_test \
test/support/interpreters \
test/test_asyncio \
test/test_capi \
test/test_cext \
test/test_concurrent_futures \
test/test_cppext \
test/test_ctypes \

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Add ``test_cext`` test: build a C extension to check if the Python C API
emits C compiler warnings. Patch by Victor Stinner.