Confusing error message: List item 0 has incompatible type "Type[Linear]"; expected "Type[Linear]"

[ezyang]

Bug Report

In some situations, mypy can report that there was an incompatible type X, but then say that the expected type was also X. Regardless of whether or not the program is correct or not, this error message is bad.

To Reproduce

from typing import Any
        
class Linear:
    def __init__(self, **kwargs) -> None:
        pass

class QatLinear(Linear):
    def __init__(self, qconfig=None):
        pass

def f(x: Any):
    if type(x) in [Linear, QatLinear]:
        pass

Expected Behavior mypy gives me a good error message

Actual Behavior

(base) ezyang-mbp:~ ezyang$ mypy t.py
t.py:12: error: List item 0 has incompatible type "Type[Linear]"; expected "Type[Linear]"
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: mypy 0.780
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: Python 3.7
• Operating system and version: OS X

[ezyang]

Possibly related: #9756

[EugeneN]

this happens quite often btw