emacs.pkgs.ghostel: teach updateScript to update vendored zig deps (#544551)

pkgs/applications/editors/emacs/elisp-packages/manual-packages/ghostel/package.nix

@@ -12,6 +12,46 @@
 let
   zig = zig_0_15;
 
+  mkModule =
+    {
+      pname,
+      version,
+      src,
+      zigDeps,
+    }:
+    stdenv.mkDerivation (finalAttrs: {
+      inherit
+        pname
+        version
+        src
+        zigDeps
+        ;
+
+      nativeBuildInputs = [ zig ] ++ lib.optionals stdenv.hostPlatform.isDarwin [ xcbuild ];
+
+      env.EMACS_INCLUDE_DIR = "${emacs}/include";
+
+      dontSetZigDefaultFlags = true;
+
+      doCheck = true;
+
+      zigCheckFlags = [
+        "-Dcpu=baseline"
+        # See https://github.com/ghostty-org/ghostty/blob/main/PACKAGING.md#build-options
+        "-Doptimize=ReleaseFast"
+      ];
+
+      zigBuildFlags = finalAttrs.zigCheckFlags;
+
+      postConfigure = ''
+        cp -rLT ${finalAttrs.zigDeps} "$ZIG_GLOBAL_CACHE_DIR/p"
+        chmod -R u+w "$ZIG_GLOBAL_CACHE_DIR/p"
+      '';
+    });
+
+  libExt = stdenv.hostPlatform.extensions.sharedLibrary;
+in
+melpaBuild (finalAttrs: {
   pname = "ghostel";
 
   version = "0.44.0";
@@ -19,59 +59,37 @@ let
   src = fetchFromGitHub {
     owner = "dakra";
     repo = "ghostel";
-    tag = "v${version}";
+    tag = "v${finalAttrs.version}";
     hash = "sha256-vRGZoQtjsL42ga07fOfEjccKRidAhqgwHBoKs++62Ls=";
   };
 
-  module = stdenv.mkDerivation (finalAttrs: {
-    inherit pname version src;
-
-    deps = zig.fetchDeps {
-      inherit (finalAttrs) src pname version;
-      fetchAll = true;
-      hash = "sha256-yrVgiofdmVjTGJ+PGPGRCc8gb/JcEca1uAzIoPgHHqU=";
-    };
-
-    nativeBuildInputs = [ zig ] ++ lib.optionals stdenv.hostPlatform.isDarwin [ xcbuild ];
-
-    env.EMACS_INCLUDE_DIR = "${emacs}/include";
-
-    dontSetZigDefaultFlags = true;
-
-    doCheck = true;
-
-    zigCheckFlags = [
-      "-Dcpu=baseline"
-      # See https://github.com/ghostty-org/ghostty/blob/main/PACKAGING.md#build-options
-      "-Doptimize=ReleaseFast"
-    ];
-
-    zigBuildFlags = finalAttrs.zigCheckFlags;
-
-    postConfigure = ''
-      cp -rLT ${finalAttrs.deps} "$ZIG_GLOBAL_CACHE_DIR/p"
-      chmod -R u+w "$ZIG_GLOBAL_CACHE_DIR/p"
-    '';
-  });
-
-  libExt = stdenv.hostPlatform.extensions.sharedLibrary;
-in
-melpaBuild {
-  inherit pname version src;
+  # this can be put into mkModule, but we put it here to ease user overrideAttrs
+  zigDeps = zig.fetchDeps {
+    inherit (finalAttrs) src pname version;
+    fetchAll = true;
+    hash = "sha256-yrVgiofdmVjTGJ+PGPGRCc8gb/JcEca1uAzIoPgHHqU=";
+  };
 
   files = ''
     (:defaults "etc" "ghostel-module${libExt}" "ghostel-module.version")
   '';
 
   preBuild = ''
-    install ${module}/ghostel-module${libExt} ghostel-module${libExt}
-    install --mode=444 ${module}/ghostel-module.version ghostel-module.version
+    install ${finalAttrs.finalPackage.module}/ghostel-module${libExt} ghostel-module${libExt}
+    install --mode=444 ${finalAttrs.finalPackage.module}/ghostel-module.version ghostel-module.version
   '';
 
   passthru = {
     updateScript = nix-update-script { };
 
-    inherit module;
+    module = mkModule {
+      pname = "${finalAttrs.pname}-module";
+      inherit (finalAttrs)
+        version
+        src
+        zigDeps
+        ;
+    };
   };
 
   meta = {
@@ -83,4 +101,4 @@ melpaBuild {
     ];
     license = lib.licenses.gpl3Plus;
   };
-}
+})