Allow self binding for generic ParamSpec

[cdce8p (Marc Mueller)]

@erictraut

When you call self.method2(2), the first parameter (which I renamed __self) is bound to an instance of Wrapper. There is no opportunity to bind the second parameter (self) to an instance of A.

I’m not sure what you’re proposing when you say “allow self binding for generic ParamSpec”.

I think of it as implicitly passing Self@A as argument if method2 is called with self, type[Self]@A in case the method is a @classmethod and not passing it for @staticmethod (same as for A.method2).

@erictraut

I’ll note that this gets even more complicated when a return type is captured along with a signature and that return type depends on the type of the self parameter. For example:

Return Self is indeed an interesting case. Notably, it doesn’t work currently with neither pyright nor mypy. For reveal_type(self.method2() pyright returns Unknown, whereas mypy even complains about a missing positional argument “self” and infers it as Never. This At least for mypy this suggests to me that the Self@A instance isn’t passed along which this proposal aims to resolve.

With the mypy change above, it would be inferred as R'5 i.e. Any.