modules/performance: add an option to combine plugins to a single plugin pack

modules/default.nix

@@ -19,6 +19,7 @@
     ./lua-loader.nix
     ./opts.nix
     ./output.nix
+    ./performance.nix
     ./plugins.nix
   ];
 }

modules/performance.nix

@@ -0,0 +1,54 @@
+{ lib, ... }:
+let
+  inherit (lib) types;
+in
+{
+  options.performance = {
+    combinePlugins = {
+      enable = lib.mkEnableOption "combinePlugins" // {
+        description = ''
+          Whether to enable EXPERIMENTAL option to combine all plugins
+          into a single plugin pack. It can significantly reduce startup time,
+          but all your plugins must have unique filenames and doc tags.
+          Any collision will result in a build failure.
+          Only standard neovim runtime directories are linked to the combined plugin.
+          If some of your plugins contain important files outside of standard
+          directories, add these paths to `pathsToLink` option.
+        '';
+      };
+      pathsToLink = lib.mkOption {
+        type = with types; listOf str;
+        default = [ ];
+        example = [ "/data" ];
+        description = "List of paths to link into a combined plugin pack.";
+      };
+    };
+  };
+
+  config.performance = {
+    # Set option value with default priority so that values are appended by default
+    combinePlugins.pathsToLink = [
+      # :h rtp
+      "/autoload"
+      "/colors"
+      "/compiler"
+      "/doc"
+      "/ftplugin"
+      "/indent"
+      "/keymap"
+      "/lang"
+      "/lua"
+      "/pack"
+      "/parser"
+      "/plugin"
+      "/queries"
+      "/rplugin"
+      "/spell"
+      "/syntax"
+      "/tutor"
+      "/after"
+      # ftdetect
+      "/ftdetect"
+    ];
+  };
+}

modules/top-level/output.nix

@@ -74,15 +74,54 @@ in
 
   config =
     let
+      # Plugin list extended with dependencies
+      allPlugins =
+        let
+          pluginWithItsDeps = p: [ p ] ++ builtins.concatMap pluginWithItsDeps p.dependencies or [ ];
+        in
+        lib.unique (builtins.concatMap pluginWithItsDeps config.extraPlugins);
+
+      # All plugins with doc tags removed
+      allPluginsOverridden = map (
+        plugin:
+        plugin.overrideAttrs (prev: {
+          nativeBuildInputs = lib.remove pkgs.vimUtils.vimGenDocHook prev.nativeBuildInputs or [ ];
+          configurePhase = builtins.concatStringsSep "\n" (
+            builtins.filter (s: s != ":") [
+              prev.configurePhase or ":"
+              "rm -vf doc/tags"
+            ]
+          );
+        })
+      ) allPlugins;
+
+      # Combine all plugins into a single pack
+      pluginPack = pkgs.vimUtils.toVimPlugin (
+        pkgs.buildEnv {
+          name = "plugin-pack";
+          paths = allPluginsOverridden;
+          inherit (config.performance.combinePlugins) pathsToLink;
+          # Remove empty directories and activate vimGenDocHook
+          postBuild = ''
+            find $out -type d -empty -delete
+            runHook preFixup
+          '';
+        }
+      );
+
+      # Combined plugins
+      combinedPlugins = [ pluginPack ];
+
+      # Plugins to use in finalPackage
+      plugins = if config.performance.combinePlugins.enable then combinedPlugins else config.extraPlugins;
+
       defaultPlugin = {
         plugin = null;
         config = "";
         optional = false;
       };
 
-      normalizedPlugins = map (
-        x: defaultPlugin // (if x ? plugin then x else { plugin = x; })
-      ) config.extraPlugins;
+      normalizedPlugins = map (x: defaultPlugin // (if x ? plugin then x else { plugin = x; })) plugins;
 
       neovimConfig = pkgs.neovimUtils.makeNeovimConfig (
         {