nixos/sddm: add layer-shell-qt to the wrapper when kwin is used

Otherwise the greeter just dies immediately.

nixos/modules/services/display-managers/sddm.nix

@@ -8,6 +8,7 @@ let
 
   sddm = cfg.package.override (old: {
     withWayland = cfg.wayland.enable;
+    withLayerShellQt = cfg.wayland.compositor == "kwin";
     extraPackages = old.extraPackages or [ ] ++ cfg.extraPackages;
   });
 

pkgs/applications/display-managers/sddm/default.nix

@@ -2,16 +2,20 @@
   lib,
   callPackage,
   runCommand,
+  layer-shell-qt,
   qtwayland,
   wrapQtAppsHook,
   unwrapped ? callPackage ./unwrapped.nix {},
   withWayland ? false,
+  withLayerShellQt ? false,
   extraPackages ? [],
 }:
 runCommand "sddm-wrapped" {
   inherit (unwrapped) version;
 
-  buildInputs = unwrapped.buildInputs ++ extraPackages ++ lib.optional withWayland qtwayland;
+  buildInputs = unwrapped.buildInputs ++ extraPackages
+    ++ lib.optional withWayland qtwayland
+    ++ lib.optional (withWayland && withLayerShellQt) layer-shell-qt;
   nativeBuildInputs = [ wrapQtAppsHook ];
 
   passthru = {

pkgs/top-level/qt6-packages.nix

@@ -104,7 +104,7 @@ makeScopeWithSplicing' {
 
   # Not a library, but we do want it to be built for every qt version there
   # is, to allow users to choose the right build if needed.
-  sddm = callPackage ../applications/display-managers/sddm {};
+  sddm = kdePackages.callPackage ../applications/display-managers/sddm {};
 
   sierra-breeze-enhanced = kdePackages.callPackage ../data/themes/kwin-decorations/sierra-breeze-enhanced { };