Confusing error: incompatible type "Type[bytes]"; expected "Type[bytes]"

[ixje]

Bug Report

Error message seems to indicate it requires the type it is getting. I could be reading the error message wrong, but this one confuses me.

To Reproduce

1. put the code in a file e.g. scratchpad.py

   from typing import Type
   
   def f(class_type: Type[object]):
      if class_type in [bytes, bytearray]:
          return True

2. run mypy scratchpad.py

Expected Behavior no errors

Actual Behavior

scratchpad.py:4: error: List item 0 has incompatible type "Type[bytes]"; expected "Type[bytes]"

Your Environment

• Mypy version used: 0.790
• Mypy command-line flags: n/a
• Mypy configuration options from mypy.ini (and other config files): n/a
• Python version used: 3.8.3
• Operating system and version: OSX 10.15.7

[hauntsaninja]

Here's a shorter repro:

[bytes, bytearray]

See https://github.com/python/typing/issues/552 for some more context.

A good workaround here is to use a tuple instead of a list (since tuples are heterogeneous, mypy won't need to perform a join).

[JelleZijlstra]

There's still something strange going on here that the linked issue doesn't fully explain, though surely the implicit promotion has something to do with it. The error doesn't repro with [float, int] or [int, float], even though these are also implicitly promoted, or with [bytearray, bytes].

[EugeneN]

the error reproduces with arbitrary types, in function arguments, assigning etc

[EugeneN]

Argument 3 to "..." has incompatible type "List[PlatformFees]"; expected "List[PlatformFees]" mypy(error)

Argument 2 to "..." has incompatible type "CIPSolution"; expected "CIPSolution" mypy(error)