[BUG] Cannot find the `cmake` module in a wheel build venv when the `cmake` executable is installed in another venv

## Expected Behavior `cmake` should work with an arbitrary runtime environment when calling the `cmake` executable with an absolution path. ## Current Behavior When a `venv` (A) is installed with the `cmake` PyPI package, a `venv/bin/cmake` executable will present in `PATH` if the `venv` (A) is activated. While install a PyPI package from source, a build `venv` (B) will be created. In the build `venv` (B), run `cmake` installed in the `venv` (A) with absolute path will raise an error that cannot find the `cmake` module (installed in `venv` (A)). After adding some debug script to the `cmake` executable: ```diff #!${PROJECT}/venvA/bin/python3.13 # -*- coding: utf-8 -*- import re import sys + import site + from pprint import pformat + + with open('debug.txt', 'w') as f: + print(f'site-packages: {pformat(site.getsitepackages())}', file=f) + print(f'sys.path: {pformat(sys.path)}', file=f) + from cmake import cmake if __name__ == '__main__': sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0]) sys.exit(cmake()) ``` I got: ```text site-packages: ['${PROJECT}/venvA/lib/python3.13/site-packages'] sys.path: ['${PROJECT}/venvA/bin', '${TMP}/pip-build-env-xxx/site', '/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python313.zip', '/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13', '/opt/homebrew/Cellar/python@3.13/3.13.2/Frameworks/Python.framework/Versions/3.13/lib/python3.13/lib-dynload', '${TMP}/pip-build-env-xxx/overlay/lib/python3.13/site-packages', '${TMP}/pip-build-env-xxx/normal/lib/python3.13/site-packages'] ``` where the `site-packages` of `venv` (A) is not present in `sys.path`. ## Reproduce Script ```python # setup.py import os import shutil from pathlib import Path from setuptools import Extension, setup from setuptools.command.build_ext import build_ext HERE = Path(__file__).absolute().parent class CMakeExtension(Extension): def __init__(self, name, source_dir=".", target=None, **kwargs): super().__init__(name, sources=[], **kwargs) self.source_dir = Path(source_dir).absolute() self.target = target if target is not None else name.rpartition(".")[-1] @classmethod def cmake_executable(cls): cmake = os.getenv("CMAKE_EXECUTABLE", "") if not cmake: cmake = shutil.which("cmake") return cmake class cmake_build_ext(build_ext): def build_extension(self, ext): if not isinstance(ext, CMakeExtension): super().build_extension(ext) return cmake = ext.cmake_executable() if cmake is None: raise RuntimeError("Cannot find CMake executable.") self.spawn([cmake, "--version"]) setup( name="cmake-venv-test", version="0.0.1", cmdclass={"build_ext": cmake_build_ext}, ext_modules=[CMakeExtension("cmake_venv_test._C", source_dir=HERE)], ) ``` ```console $ python3 -m venv venv $ source venv/bin/activate $ pip3 install cmake $ which cmake ${PROJECT}/venv/bin/cmake $ pip3 install . Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple Processing ${PROJECT} Installing build dependencies ... done Getting requirements to build wheel ... done Preparing metadata (pyproject.toml) ... done Building wheels for collected packages: cmake-venv-test Building wheel for cmake-venv-test (pyproject.toml) ... error error: subprocess-exited-with-error × Building wheel for cmake-venv-test (pyproject.toml) did not run successfully. │ exit code: 1 ╰─> [9 lines of output] running bdist_wheel running build running build_ext ${PROJECT}/venv/bin/cmake --version Traceback (most recent call last): File "${PROJECT}/venv/bin/cmake", line 5, in <module> from cmake import cmake ModuleNotFoundError: No module named 'cmake' error: command '${PROJECT}/venv/bin/cmake' failed with exit code 1 [end of output] note: This error originates from a subprocess, and is likely not a problem with pip. ERROR: Failed building wheel for cmake-venv-test Failed to build cmake-venv-test ERROR: Failed to build installable wheels for some pyproject.toml based projects (cmake-venv-test) ``` ## Additional Context Related: - metaopt/optree#187 - metaopt/optree#188 The above issue and PR changed to use the `cmake` executable in `PATH` instead of adding the `cmake` PyPI package to `build-system.requires` in `pyproject.toml`. cc @mgorny