Use TemporaryFile for test code compilation

[tobiasdiez]

Use tempfile.TemporaryFile instead of Sage's own temporary file handler for the compilation of the test cython file.

This fixes errors during test collection with pytest:

conftest.py:129: in collect
    for test in finder.find(module, module.__name__):
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:948: in find
    self._find(tests, obj, name, module, source_lines, globs, {})
conftest.py:82: in _find
    super()._find(  # type:ignore[misc]
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:1022: in _find
    self._find(tests, val, valname, module, source_lines,
conftest.py:82: in _find
    super()._find(  # type:ignore[misc]
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:1010: in _find
    test = self._get_test(obj, name, module, globs, source_lines)
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:1092: in _get_test
    return self._parser.get_doctest(docstring, globs, name,
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:684: in get_doctest
    return DocTest(self.get_examples(string, name), globs,
../../../miniconda3/envs/sage-dev/lib/python3.12/doctest.py:698: in get_examples
    return [x for x in self.parse(string, name)
../../../miniconda3/envs/sage-dev/lib/python3.12/site-packages/sage/doctest/parsing.py:1111: in parse
    elif tag not in available_software:
../../../miniconda3/envs/sage-dev/lib/python3.12/site-packages/sage/doctest/external.py:489: in __contains__
    elif feature.is_present():
../../../miniconda3/envs/sage-dev/lib/python3.12/site-packages/sage/features/__init__.py:211: in is_present
    res = self._is_present()
../../../miniconda3/envs/sage-dev/lib/python3.12/site-packages/sage/features/__init__.py:924: in _is_present
    with open(tmp_filename(ext='.pyx'), 'w') as pyx:
../../../miniconda3/envs/sage-dev/lib/python3.12/site-packages/sage/misc/temporary_file.py:126: in tmp_filename
    handle, tmp = tempfile.mkstemp(prefix=name,
../../../miniconda3/envs/sage-dev/lib/python3.12/tempfile.py:357: in mkstemp
    return _mkstemp_inner(dir, prefix, suffix, flags, output_type)
../../../miniconda3/envs/sage-dev/lib/python3.12/tempfile.py:256: in _mkstemp_inner
    fd = _os.open(file, flags, 0o600)
E   FileNotFoundError: [Errno 2] No such file or directory: '/tmp/sage__ig56pe8/tmp_tjklyklm.pyx'

https://github.com/sagemath/sage/actions/runs/13718450041/job/38368348037?pr=39641#step:13:2369

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[orlitzky]

I don't think this will work on POSIX systems. The docs say,

The returned object is a true file object on POSIX platforms. On other platforms, it is a file-like object whose file attribute is the underlying true file object.

What it does on my machine:

>>> import tempfile
>>> with tempfile.TemporaryFile() as f:
...     print(f.name)
... 
3

[tobiasdiez]

Right, it should have used NamedTemporaryFile. Strange thing is that on CI the Cython features bliss and sage.misc.cython were nevertheless correctly recognized.

[orlitzky]

You are the only one able to test it, but I would err on the side of caution and clean up the file explicitly here (i.e. set delete=False, and unlink it when done). The docs say that reopening an open file by name is tricky on Windows:

Opening the temporary file again by its name while it is still open works as follows... On Windows, make sure that at least one of the following conditions are fulfilled:

• delete is false
• additional open shares delete access (e.g. by calling os.open() with the flag O_TEMPORARY)
• delete is true but delete_on_close is false. Note, that in this case the additional opens that do not share delete access (e.g. created via builtin open()) must be closed before exiting the context manager, else the os.unlink() call on context manager exit will fail with a PermissionError.

So ideally what we want to do is set delete_on_close=False... but the delete_on_close parameter was only added in python-3.12.

[tobiasdiez]

Thanks, that's a good point.

So ideally what we want to do is set delete_on_close=False... but the delete_on_close parameter was only added in python-3.12.

We can drop support for 3.11 this autumn and I would prefer to wait until then with improving windows support.

[dimpase]

dropping 3.11 would be nice as well to enable the use of nanobind (the successor of pybind11)

[tobiasdiez]

Sure, but that would have to wait a few more months if we want to adhere to spec 0.

[dimpase]

could you rebase this?

[tobiasdiez]

could you rebase this?

Sure, done!

[dimpase]

lgtm

[tobiasdiez]

Thanks!