Internal error occurs at @typing.overload in large protoc generated files #22257

Crash Report

When running mypy on some large protoc generated python files, it consistently returns an internal error at the same line. Unfortunately, after mypy returns this internal error, I cannot copy the contents of the command prompt. I will paste a screenshot of the error report and traceback in the traceback section.

Traceback

To Reproduce

I've attached source code to reproduce this. I was using poetry to build and run mypy, so the steps I performed are:

• Open command prompt to the package root
• Run poetry build && poetry install
• Run poetry run mypy
• See mypy take a long time and eventually fail with an internal error.

Your Environment

• Mypy version used: 2.4.0
• Mypy command-line flags: --show-traceback
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.13.15
• Operating system and version: Windows 11