Nix build failures

[nullcubee]

Trying to use the flake to build the latest version of SWWW results in the error:

nix build .#swww:

error: getting status of '/nix/store/5c8n8dlsmln8k7y4ljv9sb5kgmi8gjw4-source/build.nix': No such file or directory

It appears that the nix package (build.nix) was just completely removed in #420, which renders the overlay and the package definition in the flake.nix file useless, and breaks the devShell (nix develop).

If it was intentional for the nix package to be removed from the repo, the flake should be updated to reflect that, possibly with an error message to notify end users that the package has been removed, and the Nix section in the readme should be removed as well.

[nullcubee]

After digging around and trying to build the package for myself, I found the root issue that #420 was addressing, and made a slightly hacky workaround for it. I'm not a huge fan of it but I think the issue probably lies upstream in nixpkgs, or potentially waybackend:

Restoring the build.nix file reveals the following error, which I assume is the reason why it was removed in the first place:

thread 'main' panicked at /build/cargo-vendor-dir/waybackend-scanner-0.4.2/src/lib.rs:1086:13:
could not find wayland protocol file //nix/store/mxyi7nahmxs41d2xnyfx9kvanqh3p706-wayland-1.23.1/share/wayland/wayland.xml

Waybackend and pkg-config try to find wayland.xml in pkgs.wayland, but the file isn't included in pkgs.wayland, even though it is in the upstream repo, and the wayland-client.pc file in pkgs.wayland.dev claims that it should be there as well.

For posterity, Waybackend tries to get the file and panics here.

The wayland.xml file is included in pkgs.wayland-scanner, however when that's added to buildInputs it can't seem to find it there.

Regardless, the workaround I have made just overrides pkgs.wayland to copy the wayland.xml file into the package output, where pkg-config/waybackend expects it to be.

(Thank you @Zynh0722 for helping me figure this out and dig around in the rust code and the various Nix packages)