Support deep autoloading

[noverby]

It seems autoloading is only supporting one directory level for autoloading.

So this works:

nix/packages/pkg1.nix

But not this:

nix/packages/pkg-group/pkg1.nix

[accelbread]

Hmm, I'm not sure how this would generalize.

Right now we have, in order that is checked for:

• nix/packages.nix returns the value to set packages to. This is pretty clear what the user intended.
• nix/packages/default.nix returns the value to set packages to. With Nix it would be expected that default.nix should set what the folder evaluates to, and allows user to keep full control but put all files in a packages folder.
• nix/packages/ without a default.nix grabs all the nix files in the directory and sets packages to an attrset with names from file names mapping to importing that file. This makes sense since with nix/packages/a.nix and nix/packages/b.nix, the user wants to set packages.a and packages.b.

Not sure what nix/packages/pkg-group/pkg1.nix would be. I would assume it would set packages.pkg-group.pkg1 though that is not valid since packages.x86_64-linux.pkg-group.pkg1 is not valid. Only attribute, as far as I know, that allows arbitrary structure is legacyPackages.

[noverby]

I didn't know directory-based package categories will be deprecated in favor of meta.categories with RFC 146.

Which means supporting this does not make sense anymore.