Bug report

Bug description:

We can create inspect.Signature with two or more variable parameters, but this will be syntactically incorrect when defining the function manually:

import inspect

parameters = [
    inspect.Parameter("args", kind=inspect.Parameter.VAR_POSITIONAL),
    inspect.Parameter("other_args", kind=inspect.Parameter.VAR_POSITIONAL),
    inspect.Parameter("kwargs", kind=inspect.Parameter.VAR_KEYWORD),
    inspect.Parameter("other_kwargs", kind=inspect.Parameter.VAR_KEYWORD),
]

signature = inspect.Signature(parameters)
print(signature)

OUTPUT:

(*args, *other_args, **kwargs, **other_kwargs)

And naturally we get a syntax error when defining a function with such a signature:

def func(*args, *other_args, **kwargs, **other_kwargs):
    ...

OUTPUT:

  File "/home/apostol_fet/inspect_signature.py", line 13
    def func(*args, *other_args, **kwargs, **other_kwargs):
                    ^
SyntaxError: * argument may appear only once

Can we add validations for this case in inspect.Signature.__init__?
I would like to send a PR to fix this if it is not intended behavior.

CPython versions tested on:

3.12

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-127610: Added validation for more than one var positional and var keyword parameters in inspect.Signature #127657