The TestProtocol enum does weird stuff in __str__, accessing other enum members via self #8318
Description
Hello. We are testing Python packages in Fedora with Python 3.10 to see what breaks. Packages using meson fail with:
Found ninja-1.10.2 at /usr/bin/ninja
File "/usr/lib/python3.10/site-packages/mesonbuild/mesonmain.py", line 140, in run
return options.run_func(options)
File "/usr/lib/python3.10/site-packages/mesonbuild/msetup.py", line 253, in run
app.generate()
File "/usr/lib/python3.10/site-packages/mesonbuild/msetup.py", line 161, in generate
self._generate(env)
File "/usr/lib/python3.10/site-packages/mesonbuild/msetup.py", line 235, in _generate
mintro.generate_introspection_file(b, intr.backend)
File "/usr/lib/python3.10/site-packages/mesonbuild/mintro.py", line 470, in generate_introspection_file
intro_info += [(key, val.func())]
File "/usr/lib/python3.10/site-packages/mesonbuild/mintro.py", line 77, in <lambda>
('tests', IntroCommand('List all unit tests', func=lambda: list_tests(testdata))),
File "/usr/lib/python3.10/site-packages/mesonbuild/mintro.py", line 342, in list_tests
return get_test_list(testdata)
File "/usr/lib/python3.10/site-packages/mesonbuild/mintro.py", line 336, in get_test_list
to['protocol'] = str(t.protocol)
File "/usr/lib/python3.10/site-packages/mesonbuild/backend/backends.py", line 59, in __str__
if self is self.EXITCODE:
File "/usr/lib64/python3.10/enum.py", line 146, in __get__
raise AttributeError(
AttributeError: TestProtocol: no attribute 'EXITCODE'
This comes from:
meson/mesonbuild/backend/backends.py
Lines 52 to 78 in 398df56
The __str__ method accesses other enum members via self.<name>.
I've reported this as a regression to Python, because it used to work prior to 3.10.0a5 and no longer does. It seems however, that the author of enum doesn't think this is a proper API, and while they agree to keep it working in Python 3.10, they might end up adding a deprecation warning. https://bugs.python.org/issue43162
Possibly, the method could be simplified to:
def __str__(self) -> str:
return self.name.lower()?