Condition can't be inferred, unable to merge overloads

Bug Report

I don't know how to describe it, but mypy throws the Condition can't be inferred, unable to merge overloads error

To Reproduce

Gist URL: https://gist.github.com/mypy-play/db2fda335634c93b6c2b044b98fd5c71
Playground URL: https://mypy-play.net/?mypy=master&python=3.13&gist=db2fda335634c93b6c2b044b98fd5c71

def any_function() -> None: ...


if 'Any expression':

    @any_function
    def _(): ...


def _(): ...

Expected Behavior

Works fine, at least without this misc

Actual Behavior

❯ mypy mypy.py 
mypy.py:4: error: Condition can't be inferred, unable to merge overloads  [misc]
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: mypy 1.17.0 (compiled: yes)
• Mypy command-line flags: mypy mypy.py
• Mypy configuration options from mypy.ini (and other config files): nope
• Python version used: 3.10.18

Inizia eseguendo il riproduttore minimo dell’issue con mypy 1.17.0 e confronta la diagnostica relativa alla condizione e all’unione degli overload. Traccia il punto in cui viene emesso Condition can't be inferred, unable to merge overloads, quindi aggiungi una copertura di regressione che dimostri che questo esempio non segnala più l’errore misc, preservando al contempo le diagnostiche degli overload pertinenti.