xcp: install shell completions (#432877)

pkgs/by-name/xc/xcp/package.nix

@@ -4,6 +4,7 @@
   lib,
   acl,
   nix-update-script,
+  installShellFiles,
 }:
 
 rustPlatform.buildRustPackage (finalAttrs: {
@@ -19,6 +20,8 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   cargoHash = "sha256-9cNu0cgoo0/41daJwy/uWIXa2wFhYkcPhJfA/69DVx0=";
 
+  nativeBuildInputs = [ installShellFiles ];
+
   checkInputs = [ acl ];
 
   # disable tests depending on special filesystem features
@@ -32,6 +35,13 @@ rustPlatform.buildRustPackage (finalAttrs: {
     "test_no_perms"
   ];
 
+  postInstall = ''
+    installShellCompletion --cmd xcp \
+      --bash completions/xcp.bash \
+      --fish completions/xcp.fish \
+      --zsh completions/xcp.zsh
+  '';
+
   passthru.updateScript = nix-update-script { };
 
   meta = {