gh-74044: inspect.signature for wrappers around decorated bound methods

[anton-ryzhov]

If we wrap function with bound method, which is also a wrapper around function, inspect.signature will not do skip_bound_arg.
It will use inspect.unwrap and pass by bound method from outer function to inner one.

Reproducer:

import functools, inspect


def decorator(func):
    @functools.wraps(func)
    def inner(*args):
        return func(*args)
    return inner


class Foo(object):
    @decorator
    def bar(self, testarg):
        pass


f = Foo()
baz = decorator(f.bar)
assert inspect.signature(baz) == inspect.signature(f.bar)

• Issue: inspect.signature includes bound argument for wrappers around decorated bound methods #74044

[mention-bot]

@anton-ryzhov, thanks for your PR! By analyzing the history of the files in this pull request, we identified @1st1, @larryhastings and @zestyping to be potential reviewers.

[anton-ryzhov]

@the-knights-who-say-ni Got "Contributor Form Received"

[1st1]

@anton-ryzhov Good catch. The code looks OK, just add a comment explaining why your change works in all cases.

[anton-ryzhov]

@1st1 In case you haven't received notification about last push, I'm notifying about this by the comment.

[vstinner]

I removed the " needs backport to 3.6" label, the 3.6 branch no longer accept bugfixes (only security fixes are accepted): https://devguide.python.org/#status-of-python-branches

[csabella]

@1st1, I believe your requested changes have been made and this is ready for another review. Thanks!

[csabella]

Closing and reopening to trigger tests.

[MaxwellDupre]

Tested as per given test case, result pass.
Module test passed test_inspect.
Noted make failed to build nis module.
Looks ok to me.

[bedevere-bot]

Most changes to Python require a NEWS entry.

Please add it using the blurb_it web app or the blurb command-line tool.

[iritkatriel]

@anton-ryzhov This needs a news entry.

[anton-ryzhov]

Done

[miss-islington]

Thanks @anton-ryzhov for the PR, and @iritkatriel for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10, 3.11.
🐍🍒⛏🤖

[bedevere-bot]

GH-99328 is a backport of this pull request to the 3.11 branch.

[bedevere-bot]

GH-99329 is a backport of this pull request to the 3.10 branch.