Test suite expects _stat extension to be available

[vstinner]

Bug report

Checklist

• I am confident this is a bug in CPython, not a bug in a third-party project
• I have searched the CPython issue tracker,
  and am confident this bug has not been reported before

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

A clear and concise description of the bug:

The _stat extension is specific to CPython. For example, PyPy has no _stat module.

But the Python test suite expects the _stat module to be available: test_inspect, test_pydoc, and test_tarfile fail with it's missing.

Disable compilation of the _stat extension to reproduce the issue:

diff --git a/Modules/Setup.bootstrap.in b/Modules/Setup.bootstrap.in
index 8ef0f203a8..a1f6b8cc85 100644
--- a/Modules/Setup.bootstrap.in
+++ b/Modules/Setup.bootstrap.in
@@ -29,7 +29,7 @@ _abc _abc.c
 _functools _functoolsmodule.c
 _locale _localemodule.c
 _operator _operator.c
-_stat _stat.c
+#_stat _stat.c
 _symtable symtablemodule.c
 
 # for systems without $HOME env, used by site._getuserbase()

Example:

$ ./python -c 'import _stat'
ModuleNotFoundError: No module named '_stat'

Linked PRs

• gh-108638: Fix stat.filemode() when _stat is missing #108639
• gh-108638: Fix tests when _stat extension is missing #108689

[sobolevn]

Some time ago I opened the exact same issue, but about _functools extension.
Tests is written in a way that expect _functools to always be there. However, other iterpreters may not have it.

My PR was rejected :(
https://bugs.python.org/issue46647

[vstinner]

Some time ago I opened the exact same issue, but about _functools extension.

pypy3 (PyPy 3.9.16 v7.3.12) doesn't have the _functools module, but pypy2 (PyPy 2.7.18 v7.3.12) has the _functools module. It may help to make test_functools compatible with PyPy to support the case when _functools is missing. I didn't look if your proposed change make functools and/or test_functools maintenance too complicated or not.

[sunmy2019]

The _stat extension is specific to CPython. For example, PyPy has _stat module.

Do you mean "PyPy doesn't have _stat module"?

[vstinner]

Do you mean "PyPy doesn't have _stat module"?

Oops, right:

$ pypy3
Python 3.9.17 (a61d7152b989, Aug 13 2023, 10:27:46)
[PyPy 7.3.12 with GCC 13.2.1 20230728 (Red Hat 13.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>>> import _stat
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named '_stat'

[gvanrossum]

Seems fixed now.