Put the .mypy_cache directory near the project configuration file instead of at the current working directory

Feature

If there is a project configuration file (pyproject.toml, mypy.ini etc), make the default .mypy_cache directory be near the configuration file instead of at the current working directory.

Pitch

Currently, the .mypy_cache directory is created by default in the current working directory. I was very surprised to find this. It means that I probably have many .mypy_cache directories hanging around in unexpected places, possibly in unrelated projects. It also means that I had to wait for the cache to be rebuilt when there was a perfectly good cache sitting elsewhere.

I think that when there is a notion of a project, the .mypy_cache directory should be at the root of the project. So, when mypy uses a project configuration file, I think that since there is an obvious project directory, the .mypy_cache directory should be there.

まず、mypy によるプロジェクト設定の検出処理と、.mypy_cache のデフォルトの場所を選択するコードを追跡します。pyproject.toml、mypy.ini、および関連する設定ファイルがどのようにプロジェクトディレクトリを確立するかを確認し、そのうえで、設定済みの実行とカレントワーキングディレクトリからの実行に対する動作を定義してテストします。