gh-107782: Use _testcapi to test non-representable signatures

[serhiy-storchaka]

Builtin functions and methods that have non-representable signatures today will have representable signatures yesterday, and they will become unusable for testing this feature.

So we need to add special functions and methods to the _testcapi module that always have non-representable signatures.

• Issue: Pydoc: fall back to __text_signature__ if inspect.signature() fails #107782

[serhiy-storchaka]

I do not understand why Tools/c-analyzer/check-c-globals.py complains about DocStringUnrepresentableSignatureTest, but not about DocStringNoSignatureTest in Modules/_testcapi/docstring.c. They are almost identical, only names and methods are different. Both are added by me, so there is no any special magic hidden.

@ericsnowcurrently, could you explain this?

[ericsnowcurrently]

Unfortunately, the tool never learned to reliably identify implicitly-const static definitions (e.g. Py*Def arrays/structs like the PyMethodDef one you added in this PR). Instead, such variables usually have to be manually added to Tools/c-analyzer/cpython/ignored.tsv. DocStringNoSignatureTest was added there a while back.

You can move the entry you added to globals-to-fix.tsv over to ignored.tsv.

[serhiy-storchaka]

Thank you Eric. I did not know about ignored.tsv.

[miss-islington]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[miss-islington]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[miss-islington]

Sorry, @serhiy-storchaka, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 1f885df2a580360c5de69cc41191f3c6bfaaeb35 3.12

[miss-islington]

Sorry, @serhiy-storchaka, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 1f885df2a580360c5de69cc41191f3c6bfaaeb35 3.11

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot PPC64LE RHEL8 LTO 3.x has failed when building commit 1f885df.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/361/builds/4050) and take a look at the build logs.
4. Check if the failure is related to this commit (1f885df) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/361/builds/4050

Failed tests:

• test.test_asyncio.test_subprocess

Failed subtests:

• test_subprocess_consistent_callbacks - test.test_asyncio.test_subprocess.SubprocessThreadedWatcherTests.test_subprocess_consistent_callbacks

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-ppc64le.lto/build/Lib/test/test_asyncio/test_subprocess.py", line 788, in test_subprocess_consistent_callbacks
    self.loop.run_until_complete(main())
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-ppc64le.lto/build/Lib/asyncio/base_events.py", line 664, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-ppc64le.lto/build/Lib/test/test_asyncio/test_subprocess.py", line 780, in main
    self.assertEqual(events, [
AssertionError: Lists differ: [('pi[29 chars]t'), 'pipe_connection_lost', ('pipe_data_recei[57 chars]ted'] != [('pi[29 chars]t'), ('pipe_data_received', 2, b'stderr'), 'pi[57 chars]ted']