false alarm on decode call

[florianschanda]

Bug Report

The following file is legal python, as far as I understand it:

import codecs

a = codecs.lookup("UTF-8")
b = bytes(b"potato")
c = a.decode(b, errors="replace")

Running mypy 2.3.1 produces:

$ mypy wibble.py
wibble.py:5: error: Unexpected keyword argument "errors" for "__call__" of "_Decoder"  [call-arg]
wibble.py:5: note: "__call__" defined in "codecs"

To Reproduce

https://mypy-play.net/?mypy=latest&python=latest&gist=e34d60fa6ddb3835c9d2dae7eae7a301

Expected Behavior

I would expect no message at all. Reasoning:

• https://docs.python.org/3/library/codecs.html#codecs.lookup describes what is returned from lookup
• https://docs.python.org/3/library/codecs.html#codecs.CodecInfo describes required API
• https://docs.python.org/3/library/codecs.html#codecs.Codec.decode describes that errors is parameter

Actual Behavior

False alarm is issued.

Your Environment

• Mypy version used: 2.3.1
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 2.13.5 (from Debian trixie)

[ilevkivskyi]

It is annotated as positional-only in typeshed, transferring there.