Spurious errors on the builtin open when running mypy on mypy

When running mypy following the procedure below, I encounter several errors for the overloaded open builtin of the form:

../python3.11/site-packages/mypy/typeshed/stdlib/builtins.pyi:1327: error: Argument 8 to "open" becomes "Optional[Any]" due to an unfollowed import  [no-any-unimported]

To reproduce:

1. Set up a virtualenv with Python 3.11 and activate it.
2. pip install mypy
3. python-m mypy --strict --no-silence-site-packages --disallow-any-unimported -m mypy

Both --no-silence-site-packages and --disallow-any-unimported need to be present.

Version 1.0.0 of mypy is required. Older versions don't exhibit this error.

This is the simplest way we have found to reproduce this problem, but we first encountered it in one of our own projects.

The issue is being filed here because the mypy docs for reporting bugs says that problems with a specific library function should be reported here. We're not seeing this error with any other functions.

Riproduci il report con Python 3.11, mypy 1.0.0 e il comando documentato usando --no-silence-site-packages e --disallow-any-unimported. Inizia esaminando typeshed/stdlib/builtins.pyi intorno alla riga 1327 e la gestione dell'open incorporato; il lavoro è completato quando il comando non segnala più gli errori no-any-unimported spuri.