strict equality check fails to detect non-overlap of str and Path

[bluenote10]

Bug Report

At runtime, comparing an instance of Path to str seems to be always negative, i.e., they don't overlap in terms of comparison.

Using the --strict-equality typically errors in such cases that are non-overlapping and cannot possibly yield True. This mechanism doesn't seem to work for Path and str, allowing to silently let such bugs pass.

To Reproduce

The following code has a bug, because the Path to str does not work as intended

from pathlib import Path

a = "/foo"
b = Path("/foo")

if a == b: # can never be true
    ...

Expected Behavior

I'd have expected a type error similar to the one for comparing e.g. str to int:

error: Non-overlapping equality check (left operand type: "str", right operand type: "Path")  [comparison-overlap]

Actual Behavior

--strict-equality has no effect here, and misses the bug.

Your Environment

• Mypy version used: 1.5.1
• Mypy command-line flags: --strict-equality
• Mypy configuration options from mypy.ini (and other config files): -
• Python version used: 3.11

[AlexWaygood]

Fixed in python/typeshed#10662 (but you might have to wait until mypy 1.7 for the fix, not sure it'll make mypy 1.6)

[AlexWaygood]

Fun fact: merging that typeshed change into mypy uncovered a bug in mypy itself: take a look at the last commit in #16121