mcat-unwrapped: add shell completions (#415029)

pkgs/by-name/mc/mcat-unwrapped/package.nix

@@ -2,6 +2,9 @@
   lib,
   rustPlatform,
   fetchFromGitHub,
+  installShellFiles,
+  stdenv,
+  buildPackages,
   nix-update-script,
 }:
 rustPlatform.buildRustPackage (finalAttrs: {
@@ -17,6 +20,25 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   cargoHash = "sha256-c3OJURz6eObjIC6AHUP6l/a5zYFV0QZ3VIxShFCcm4U=";
 
+  nativeBuildInputs = [
+    installShellFiles
+  ];
+
+  postInstall =
+    let
+      mcat =
+        if stdenv.buildPlatform.canExecute stdenv.hostPlatform then
+          placeholder "out"
+        else
+          buildPackages.mcat-unwrapped;
+    in
+    ''
+      installShellCompletion --cmd mcat \
+        --bash <(${mcat}/bin/mcat --generate bash) \
+        --fish <(${mcat}/bin/mcat --generate fish) \
+        --zsh <(${mcat}/bin/mcat --generate zsh)
+    '';
+
   passthru = {
     updateScript = nix-update-script { };
   };

pkgs/by-name/mc/mcat/package.nix

@@ -18,6 +18,7 @@ runCommand "mcat"
   }
   ''
     mkdir -p $out/bin
+    ln -s "${mcat-unwrapped}/share" "$out/share"
     makeWrapper ${lib.getExe mcat-unwrapped} $out/bin/mcat --prefix PATH : ${
       lib.makeBinPath ((lib.optional useChromium chromium) ++ (lib.optional useFfmpeg ffmpeg-headless))
     }