Context

Currently testing out the new pkgs.nixfmt-rfc-style, and it's taking forever + erroring out since it attempts to format my .gitignored .direnv/ folder:

-> $ nix fmt
nixfmt: ./.direnv/flake-inputs/5gc4ncnkzcgma8fl1qabm8v9kj7w68gl-source/doc/doc-support: openTempFileWithDefaultPermissions: permission denied (Read-only file system)

Expected behaviour

• Don't format .gitignored/otherwise explicitly ignored files/files in ignored subfolders of repository.
• Maybe (additionally, which would solve my issue w/the error, but not the runtime) ignore read-only files.

Things to consider:

• only support git ignores?
• support others?
• add a default list of elements to ignore (like .direnv/, result/)?