Type annotations for functions are absent

[arihant2math]

Bug Description

There aren't type annotation when using inspect.signature for everything but Options, which produce a Ellipsis as default argument.

Steps to Reproduce

# main.py
import inspect
import test
print(inspect.signature(test.foo))

// lib/src.rs
...
#[pyfunction]
fn foo(a: i64, b: Option<i64>) -> String {
}
...

running the python code would produce:
(a, b=Ellipsis)

Backtrace

No response

Your operating system and version

Windows

Your Python version (python --version)

3.11.2

Your Rust version (rustc --version)

rustc 1.68.0 (2c8cc3432 2023-03-06)

Your PyO3 version

0.18.1

How did you install python? Did you use a virtualenv?

python.org, a virtualenv with maturin was used

Additional Info

No response

[messense]

I think the default value is intentional at the moment

All default values are currently set to .... I think this is ok because .pyi files often do the same. Maybe for numbers, strings, None and True/False we could render these in a future PR.

See #2784

[messense]

BTW, type annotations are actually not supported in __text_signature__:

Python 3.11.0 (main, Oct 25 2022, 16:25:24) [Clang 14.0.0 (clang-1400.0.29.102)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def f(): pass
...
>>> import inspect
>>> inspect.signature(f)
<Signature ()>
>>> f.__text_signature__ = "(a:int, b:bool)"
>>> inspect.signature(f)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 3272, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 3020, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 2507, in _signature_from_callable
    return _signature_from_function(sigcls, obj,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 2342, in _signature_from_function
    return _signature_fromstr(cls, func, s, skip_bound_arg)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 2272, in _signature_fromstr
    p(name, default)
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 2249, in p
    name = parse_name(name_node)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/messense/.pyenv/versions/3.11.0/lib/python3.11/inspect.py", line 2214, in parse_name
    raise ValueError("Annotations are not currently supported")
ValueError: Annotations are not currently supported
>>>

[messense]

I think we should close this in favor of #2863?

[arihant2math]

Yeah I think that's a good idea