Spurious "Returning Any" error involving Self types

[inducer]

Bug Report

From the code in the following gist:

https://gist.github.com/inducer/bf7dd340bc752384c353335b665f4d68

I get an error (in strict mode) from code that I feel should not be producing one:

Returning Any from function declared to return "Taggable"

Seemingly in support of the assertion that the warning is spurious, the (largely equivalent) version remove_part_id_tag_2 (only a type hint added) checks OK.

To Reproduce

curl -L -O https://gist.githubusercontent.com/inducer/bf7dd340bc752384c353335b665f4d68/raw/23520c57e4dfdec2f31ae4fd083c917efa408600/mypy-remove-tag.py
$ mypy --strict mypy-remove-tag.py
mypy-remove-tag.py:13: error: Returning Any from function declared to return "Taggable"
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 0.942
• Mypy command-line flags: --show-error-codes --strict (see run-mypy.sh)
• Mypy configuration options from mypy.ini (and other config files): n/a
• Python version used: 3.10.4
• Operating system and version: Debian Linux unstable/testing

[AlexWaygood]

PEP 673 isn't yet supported by mypy, which is why you're getting strange errors here. You can follow along on progress with implementing PEP 673 support here: #11871.