bug: sway is broken with custom packages (like swayfx) coming from the nixos configuration

[ElysaSrc]

Are you following the right branch?

• My Nixpkgs and Home Manager versions are in sync

Is there an existing issue for this?

• I have searched the existing issues

Issue description

With the changes inside this commit: 3a43534

If you have a programs.sway with custom configurations at nixos level, and you put a package = null to use the os level package, it cannot validates the configuration since it will wrongly use pkgs.sway and not the nixos defined one.

To reproduce, you can have this in your nixos configuration.nix file:

    programs = {
      sway = {
        enable = true;
        package = pkgs.swayfx;
        extraSessionCommands = ''
          export SDL_VIDEODRIVER=wayland
          export MOZ_ENABLE_WAYLAND=1
          export NIXOS_OZONE_WL=1
          export QT_QPA_PLATFORM=wayland-egl
          export QT_WAYLAND_DISABLE_WINDOWDECORATION="1"
          export _JAVA_AWT_WM_NONREPARENTING=1
          export SSH_ASKPASS_REQUIRE=prefer
          export SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
        '';
        extraPackages = [];
      };
    };

and if on your home you put this:

wayland.windowManager.sway = {
   enable = true;
   package = null;
   # ...
};

The configuration will fail if you use SwayFX settings, like "blur" and stuff.

Workaround : set checkConfig = false;.
Fix : Use correctly the sway coming from the nixos configuration itself.

Maintainer CC

@amarshall @rycee

System information

- system: `"x86_64-linux"`
 - host os: `Linux 6.8.6, NixOS, 24.05 (Uakari), 24.05.20240419.5c24cf2`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.2`
 - nixpkgs: `/nix/store/v4pcs3nzx54m5bmxd39win0rgl2d2hbx-source`

[amarshall]

Fix: Use correctly the sway coming from the nixos configuration itself

It’s not possible for Home Manager to do this itself, you need to do it in NixOS config with e.g. in your NixOS config home-manager.sharedModules = [{ programs.sway.package = …; }];. This is assuming you’re building HM config via the HM NixOS module.

---

I do think that HM should probably not implicitly turn package = null into pkgs.sway for select things; here’s a PR for that (not tested too much, please try it out).