Clarification on how to configure mypy

[Ma27]

Describe the bug

With the mypy check from this repo, no files get checked with mypy on a treefmt run.

To Reproduce

Steps to reproduce the behavior:

1. Given foo/bar.py
2. Given the following treefmt-nix configuration (in flake.nix):

{
  treefmt = {
    projectRootFile = "flake.nix";
    programs = {
      nixfmt.enable = true;
      ruff.enable = true;
      mypy = {
        enable = true;
        directories = {
          ".".modules = [ "foo" ];
        };
      };
    };
  };

}

4. Now running treefmt doesn't give any mypy errors.

I think part of the problem is the following in the final treefmt config:

includes = ["./foo/**/*.py"]

This doesn't seem to give any matches in treefmt.

After that I replaced the ".".modules = ["foo"] with ".".files = [ "*.py" ]. With that I got the following error:

+ /nix/store/ryp4vp6rs3d1gk0mgj6x8bncavsp4wqa-python3.12-mypy-1.10.1/bin/mypy '' '*.py'
mypy: can't read file '*.py': No such file or directory

This is because *.py isn't a recursive glob, however it's the glob needed for treefmt to validate a change in any Python file in a repo with mypy.

Expected behavior

I don't know, not sure if this is even a bug.

What am I supposed to do to let mypy run against a given module (foo)?

System information

NixOS 24.05, treefmt 2.0.5 (via treefmt-nix 879b29a), git-hooks.nix at rev 85f7a7177c678de68224af3402ab8ee1bcee25c8.

Additional context