indirectly decorated attr.s classes are not recognized

[ealfie]

I'd like mypy to recognize attr.s decorated classes by "indirect" means.

To understand what I mean, consider the examples in the snippet below:

import attr

# example 1 (works with mypy)

@attr.s(auto_attribs=True, frozen=True)
class DirectlyDecorated:
    name: str


d = DirectlyDecorated('foo')  # no mypy error



# --- end example 1

# example 2 (does not work with mypy)

my_decorator = attr.s(auto_attribs=True, frozen=True)

@my_decorator
class IndirectlyDecorated:
    name: str


i = IndirectlyDecorated('bar')  # error: Too many arguments for "IndirectlyDecorated"

# --- end example 2


# example 3 (does not work with mypy)

class MyMeta(type):
    def __new__(cls, name, bases, dct):
        newcls = super().__new__(cls, name, bases, dct)
        newcls = my_decorator(newcls)
        return newcls


class MetaDecorated(metaclass=MyMeta):
    name: str


m = MetaDecorated('baz')  # error: Too many arguments for "MetaDecorated"

# --- end example 3

Running git master version of mypy as of today, with no arguments, I get:

snippet.py:25: error: Too many arguments for "IndirectlyDecorated"
snippet.py:43: error: Too many arguments for "MetaDecorated"

So, example 1 works as expected. Examples 2 and 3 do not work:

The same happens when using kw_only=True (that is example1 with kw_only=True works, but neither examples 2 nor 3 work with kw_only=True). In that case, the error reported is, of course,

snippet.py:25: error: Unexpected keyword argument "name" for "IndirectlyDecorated"
snippet.py:43: error: Unexpected keyword argument "name" for "MetaDecorated"

I'd like mypy to recognize the above cases so that example 2 and 3 work (with both kw_only=True and kw_only=False)

Thank you

[ilevkivskyi]

This was deliberately left out as too dynamic to support. We can possibly keep this open, but the priority is low.