$ dmypy run -- --config-file=mypy-test.ini
Daemon started
pkg/__init__.py:1: note: Revealed type is "Literal[1]?"
Success: no issues found in 1 source file
$ dmypy suggest os.path.islink --callsites
pkg/__init__.py:1: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
  ...
File ".../mypy/errors.py", line 684, in _add_error_info
  assert file not in self.flushed_files

Project:

• mypy-test.ini:

  [mypy]
  files = pkg/

• pkg/__init__.py

  reveal_type(1)

The crash happens when:

• One of the modules that are checked is emitting some kind of message (either note or error);
• The suggestion is something from mypy's automatically loaded modules (I've only tested standard library ones). Suggesting something from the checked modules does not cause the crash.

Your Environment

• Mypy version used: 2.3, master
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.13
• Operating system and version: Ubuntu 22.04