matchExt never matches top-level files

[DavHau]

Describe the bug

To Reproduce

Steps to reproduce the behavior:

1. setup filter:

nix-filter {
    # ...
    exclude = [
      (nix-filter.matchExt ".nix")
    ];
};

2. add a new line to the flake.nix
3. notice that a rebuilt of the package is triggered

Expected behavior
Adding a new line to the flake.nix should not trigger a re-build

System information

Additional context

[Jonas Chevalier]

Try without the . ;)

(nix-filter.matchExt "nix")

[DavHau]

Hm but with the . it still seems to match for files in sub-directories, in which case this would be an inconsistency.

[DavHau]

While making a minimal reproducer I noticed my assumption was wrong. (nix-filter.matchExt ".nix") does not filer anything at all.
Sorry for that.