inspect.signature includes bound argument for wrappers around decorated bound methods

[e336c477-85a4-4cba-9e8f-2337c82de322]

BPO	29858
Nosy	@1st1, @anton-ryzhov
PRs	python/cpython#736

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-03-20.09:19:13.208>
labels = ['type-bug', 'library', '3.9', '3.10', '3.11']
title = 'inspect.signature includes bound argument for wrappers around decorated bound methods'
updated_at = <Date 2022-01-21.12:39:17.450>
user = 'https://github.com/anton-ryzhov'

bugs.python.org fields:

activity = <Date 2022-01-21.12:39:17.450>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-03-20.09:19:13.208>
creator = 'anton-ryzhov'
dependencies = []
files = []
hgrepos = []
issue_num = 29858
keywords = []
message_count = 2.0
messages = ['289879', '289880']
nosy_count = 2.0
nosy_names = ['yselivanov', 'anton-ryzhov']
pr_nums = ['736']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29858'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[e336c477-85a4-4cba-9e8f-2337c82de322]

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)

[e336c477-85a4-4cba-9e8f-2337c82de322]

Related to http://bugs.python.org/issue24298