swift-format: add shell completions support (#506188)

pkgs/development/compilers/swift/swift-format/default.nix

@@ -1,11 +1,11 @@
 {
   lib,
   stdenv,
-  fetchpatch,
   callPackage,
   swift,
   swiftpm,
   swiftpm2nix,
+  installShellFiles,
   Dispatch,
   Foundation,
 }:
@@ -22,6 +22,7 @@ stdenv.mkDerivation {
   nativeBuildInputs = [
     swift
     swiftpm
+    installShellFiles
   ];
   buildInputs = [ Foundation ];
 
@@ -38,6 +39,16 @@ stdenv.mkDerivation {
     binPath="$(swiftpmBinPath)"
     mkdir -p $out/bin
     cp $binPath/swift-format $out/bin/
+
+    # Generate shell completions
+    for shell in bash zsh fish; do
+      $out/bin/swift-format --generate-completion-script $shell > swift-format.$shell
+    done
+
+    installShellCompletion --cmd swift-format \
+      --bash swift-format.bash \
+      --zsh swift-format.zsh \
+      --fish swift-format.fish
   '';
 
   meta = {