Issues with solving value constrained type var in presence of Any

Bug Report

In 1.11.0, classes that inherit from os.PathLike could be used with os.path methods. As of 3.12, these methods claim to accept "any object implementing the os.PathLike protocol". However, in 1.12.0, mypy emits an error.

To Reproduce

import os


class MyPath(os.PathLike):
    def __init__(self, path: str):
        super().__init__()
        self.path = path

    def __fspath__(self):
        return self.path


print(os.path.abspath(MyPath(".")))

Expected Behavior

Unless I'm missing something, MyPath should be valid to pass, no?

Actual Behavior

pathlike.py:13: error: Value of type variable "AnyStr" of "abspath" cannot be "MyPath | Any"

Your Environment

• Mypy version used: 1.12.0
• Mypy command-line flags: N/A
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.12

Start with the provided Python reproducer using os.PathLike, os.path.abspath, and the MyPath class, and compare behavior between mypy 1.11.0 and 1.12.0 on Python 3.12. Trace how the type checker handles the constrained AnyStr type variable when MyPath and Any are involved; done means the reproducer type-checks without the reported error while preserving valid diagnostics.