Uncaught ValueError in inspect.signature()

[sth]

Things to check first

• I have searched the existing issues and didn't find my bug already reported there

• I have checked that my bug is still present in the latest release

Typeguard version

4.4.1

Python version

3.13.0

What happened?

In check_signature_compatible(), Typeguard calls inspect.signature(), which can fail with ValueError if the signature cannot be determined for some reason. Typeguard should catch that error and probably ignore/skip the problematic signature check. Currently the exception falls through to the calling code:

Traceback (most recent call last):
[...]
  File "/data/src/converters/pb2.py", line 157, in _populate_entry_pb2
    def _populate_entry_pb2(
    ...<30 lines>...
            )
  File "/usr/local/lib/python3.13/site-packages/typeguard/_functions.py", line 137, in check_argument_types
    check_type_internal(value, annotation, memo)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/typeguard/_checkers.py", line 946, in check_type_internal
    checker(value, origin_type, args, memo)
    ~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/typeguard/_checkers.py", line 837, in check_protocol
    check_signature_compatible(subject, origin_type, attrname)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/typeguard/_checkers.py", line 651, in check_signature_compatible
    subject_sig = inspect.signature(getattr(subject, attrname))
  File "/usr/local/lib/python3.13/inspect.py", line 3340, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped,
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                                   globals=globals, locals=locals, eval_str=eval_str)
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/inspect.py", line 3066, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
                                    follow_wrapper_chains=follow_wrapped,
                                    globals=globals, locals=locals, eval_str=eval_str)
  File "/usr/local/lib/python3.13/inspect.py", line 2578, in _signature_from_callable
    return _signature_from_builtin(sigcls, obj,
                                   skip_bound_arg=skip_bound_arg)
  File "/usr/local/lib/python3.13/inspect.py", line 2364, in _signature_from_builtin
    raise ValueError("no signature found for builtin {!r}".format(func))
ValueError: no signature found for builtin <method 'add' of 'google._upb._message.RepeatedCompositeContainer' objects>

How can we reproduce the bug?

Since datetime.timedelta seems to have a similar problem with inspect.signature, the issue can be reproduced like this:

from typing import Protocol
from datetime import timedelta
from typeguard import typechecked

class Proto(Protocol):
    def attr(self) -> None:
        pass

class Obj(object):
    attr = timedelta

@typechecked
def f(param: Proto) -> None:
    pass

f(Obj())