git-cliff: Add man page and shell completion (#346697)

pkgs/applications/version-management/git-cliff/default.nix

@@ -4,6 +4,7 @@
 , rustPlatform
 , Security
 , SystemConfiguration
+, installShellFiles
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -26,6 +27,23 @@ rustPlatform.buildRustPackage rec {
     Security SystemConfiguration
   ];
 
+  nativeBuildInputs = [ installShellFiles ];
+
+  postInstall = lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+    export OUT_DIR=$(mktemp -d)
+
+    # Generate shell completions
+    $out/bin/git-cliff-completions
+    installShellCompletion \
+      --bash $OUT_DIR/git-cliff.bash \
+      --fish $OUT_DIR/git-cliff.fish \
+      --zsh $OUT_DIR/_git-cliff
+
+    # Generate man page
+    $out/bin/git-cliff-mangen
+    installManPage $OUT_DIR/git-cliff.1
+  '';
+
   meta = with lib; {
     description = "Highly customizable Changelog Generator that follows Conventional Commit specifications";
     homepage = "https://github.com/orhun/git-cliff";