cpython/Lib/test/test_cppext.py

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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.path
import sys
import unittest
import subprocess
import sysconfig
from test import support
from test.support import os_helper
MS_WINDOWS = (sys.platform == 'win32')
SETUP_TESTCPPEXT = support.findfile('setup_testcppext.py')
@support.requires_subprocess()
class TestCPPExt(unittest.TestCase):
def test_build_cpp11(self):
self.check_build(False, '_testcpp11ext')
def test_build_cpp03(self):
self.check_build(True, '_testcpp03ext')
# With MSVC, the linker fails with: cannot open file 'python311.lib'
# https://github.com/python/cpython/pull/32175#issuecomment-1111175897
@unittest.skipIf(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, std_cpp03, extension_name):
# Build in a temporary directory
with os_helper.temp_cwd():
self._check_build(std_cpp03, extension_name)
def _check_build(self, std_cpp03, extension_name):
venv_dir = 'env'
verbose = support.verbose
# Create virtual environment to get setuptools
cmd = [sys.executable, '-X', 'dev', '-m', 'venv', venv_dir]
if verbose:
print()
print('Run:', ' '.join(cmd))
subprocess.run(cmd, check=True)
# Get the Python executable of the venv
python_exe = 'python'
if sys.executable.endswith('.exe'):
python_exe += '.exe'
if MS_WINDOWS:
python = os.path.join(venv_dir, 'Scripts', python_exe)
else:
python = os.path.join(venv_dir, 'bin', python_exe)
def run_cmd(operation, cmd):
if verbose:
print('Run:', ' '.join(cmd))
subprocess.run(cmd, check=True)
else:
proc = subprocess.run(cmd,
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 the C++ extension
cmd = [python, '-X', 'dev',
SETUP_TESTCPPEXT, 'build_ext', '--verbose']
if std_cpp03:
cmd.append('-std=c++03')
run_cmd('Build', cmd)
# Install the C++ extension
cmd = [python, '-X', 'dev',
SETUP_TESTCPPEXT, 'install']
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,
'-X', 'dev',
'-X', 'showrefcount',
'-c', 'pass']
run_cmd('Reference run', cmd)
# Import the C++ extension
cmd = [python,
'-X', 'dev',
'-X', 'showrefcount',
'-c', f"import {extension_name}"]
run_cmd('Import', cmd)
if __name__ == "__main__":
unittest.main()