modules: refactor module bootstrapping

Let's simplify things by defining all modules in `./plugins`, `./modules`
and `./wrappers/modules`.

Instead of currying `pkgs` into a bootstrapping module, we can require
`defaultPkgs` be provided as a special arg.

This refactor allows us to completely remove `flake-modules/modules.nix`!

docs/default.nix

@@ -1,8 +1,4 @@
-{
-  rawModules,
-  helpers,
-  pkgs,
-}:
+{ helpers, pkgs }:
 let
   # Extend nixpkg's lib, so that we can handle recursive leaf types such as `either`
   lib = pkgs.lib.extend (
@@ -68,6 +64,7 @@ let
   };
 
   topLevelModules = [
+    ../modules
     ../wrappers/modules/output.nix
     # Fake module to avoid a duplicated documentation
     (lib.setDefaultModuleLocation "${nixvimPath}/wrappers/modules/files.nix" {
@@ -85,7 +82,7 @@ let
         };
       };
     })
-  ] ++ (rawModules pkgsDoc);
+  ];
 
   hmOptions = builtins.removeAttrs (lib.evalModules {
     modules = [ (import ../wrappers/modules/hm.nix { inherit lib; }) ];
@@ -97,7 +94,10 @@ rec {
       inherit
         (lib.evalModules {
           modules = topLevelModules;
-          specialArgs.helpers = helpers;
+          specialArgs = {
+            inherit helpers;
+            defaultPkgs = pkgsDoc;
+          };
         })
         options
         ;

docs/mdbook/default.nix

@@ -12,7 +12,8 @@ let
   options = lib.evalModules {
     inherit modules;
     specialArgs = {
-      inherit pkgs lib helpers;
+      inherit helpers;
+      defaultPkgs = pkgs;
     };
   };
 

flake-modules/default.nix

@@ -5,7 +5,6 @@
     ./helpers.nix
     ./lib.nix
     ./legacy-packages.nix
-    ./modules.nix
     ./overlays.nix
     ./packages.nix
     ./templates.nix

flake-modules/modules.nix

@@ -1,85 +0,0 @@
-{ modules, ... }:
-{
-  _module.args = {
-    modules =
-      pkgs:
-      let
-        nixpkgsMaintainersList = pkgs.path + "/nixos/modules/misc/meta.nix";
-
-        nixvimExtraArgsModule = rec {
-          _file = ./flake.nix;
-          key = _file;
-          config = {
-            _module.args = {
-              pkgs = pkgs.lib.mkForce pkgs;
-              inherit (pkgs) lib;
-            };
-          };
-        };
-      in
-      [
-        ../modules
-        nixpkgsMaintainersList
-        nixvimExtraArgsModule
-        (
-          { lib, ... }:
-          with lib;
-          {
-            # Attribute may contain the following fields:
-            #  - path: Path to the module, e.g. [ "plugins" "<name>" ]
-            #  - description: A short description of the plugin
-            #  - url: Url for the plugin
-            #
-            # We need to use an attrs instead of a submodule to handle the merge.
-            options.meta.nixvimInfo = mkOption {
-              type = (types.nullOr types.attrs) // {
-                # This will create an attrset of the form:
-                #
-                # { path.to.plugin.name = <info>; }
-                #
-                #
-                # Where <info> is an attrset of the form:
-                # {
-                #   file = "path";
-                #   description = null or "<DESCRIPTION>";
-                #   url = null or "<URL>";
-                # }
-                merge =
-                  _: defs:
-                  lib.foldl'
-                    (
-                      acc: def:
-                      lib.recursiveUpdate acc (
-                        setAttrByPath def.value.path {
-                          inherit (def) file;
-                          url = def.value.url or null;
-                          description = def.value.description or null;
-                        }
-                      )
-                    )
-                    {
-                      plugins = { };
-                      colorschemes = { };
-                    }
-                    defs;
-              };
-              internal = true;
-              default = null;
-              description = ''
-                Nixvim related information on the module
-              '';
-            };
-          }
-        )
-      ];
-  };
-
-  perSystem =
-    { pkgs, config, ... }:
-    {
-      _module.args = {
-        modules = modules pkgs;
-        rawModules = modules;
-      };
-    };
-}

flake-modules/packages.nix

@@ -3,13 +3,12 @@
     {
       pkgsUnfree,
       config,
-      rawModules,
       helpers,
       ...
     }:
     {
       packages = import ../docs {
-        inherit rawModules helpers;
+        inherit helpers;
         # Building the docs evaluates each plugin's default package, some of which are unfree
         pkgs = pkgsUnfree;
       };

flake-modules/wrappers.nix

@@ -1,13 +1,11 @@
 {
   inputs,
-  modules,
   getHelpers,
   self,
   ...
 }:
 let
   wrapperArgs = {
-    inherit modules;
     inherit self;
     inherit getHelpers;
   };

modules/default.nix

@@ -1,5 +1,6 @@
 {
   imports = [
+    ./misc
     ./autocmd.nix
     ./clipboard.nix
     ./colorscheme.nix

modules/misc/default.nix

@@ -0,0 +1,13 @@
+{ defaultPkgs, ... }:
+let
+  # We can't use config._module.args to define imports,
+  # so we're forced to use specialArgs.defaultPkgs's path
+  nixosModules = defaultPkgs.path + "/nixos/modules/";
+in
+{
+  imports = [
+    ./nixpkgs.nix
+    ./nixvim-info.nix
+    (nixosModules + "/misc/meta.nix")
+  ];
+}

modules/misc/nixpkgs.nix

@@ -0,0 +1,24 @@
+{
+  defaultPkgs,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  # TODO: https://github.com/nix-community/nixvim/issues/1784
+  finalPackage = defaultPkgs;
+in
+{
+  config = {
+    _module.args = {
+      # We explicitly set the default override priority, so that we do not need
+      # to evaluate finalPkgs in case an override is placed on `_module.args.pkgs`.
+      # After all, to determine a definition priority, we need to evaluate `._type`,
+      # which is somewhat costly for Nixpkgs. With an explicit priority, we only
+      # evaluate the wrapper to find out that the priority is lower, and then we
+      # don't need to evaluate `finalPkgs`.
+      pkgs = lib.mkOverride lib.modules.defaultOverridePriority finalPackage;
+      inherit (pkgs) lib;
+    };
+  };
+}

modules/misc/nixvim-info.nix

@@ -0,0 +1,48 @@
+{ lib, ... }:
+with lib;
+{
+  # Attribute may contain the following fields:
+  #  - path: Path to the module, e.g. [ "plugins" "<name>" ]
+  #  - description: A short description of the plugin
+  #  - url: Url for the plugin
+  #
+  # We need to use an attrs instead of a submodule to handle the merge.
+  options.meta.nixvimInfo = mkOption {
+    type = (types.nullOr types.attrs) // {
+      # This will create an attrset of the form:
+      #
+      # { path.to.plugin.name = <info>; }
+      #
+      #
+      # Where <info> is an attrset of the form:
+      # {
+      #   file = "path";
+      #   description = null or "<DESCRIPTION>";
+      #   url = null or "<URL>";
+      # }
+      merge =
+        _: defs:
+        lib.foldl'
+          (
+            acc: def:
+            lib.recursiveUpdate acc (
+              setAttrByPath def.value.path {
+                inherit (def) file;
+                url = def.value.url or null;
+                description = def.value.description or null;
+              }
+            )
+          )
+          {
+            plugins = { };
+            colorschemes = { };
+          }
+          defs;
+    };
+    internal = true;
+    default = null;
+    description = ''
+      Nixvim related information on the module
+    '';
+  };
+}

wrappers/_shared.nix

@@ -1,26 +1,15 @@
-{ modules, helpers }:
-{
-  lib,
-  pkgs,
-  config,
-  ...
-}:
+helpers:
+{ lib, config, ... }:
 let
-  inherit (lib)
-    mkEnableOption
-    mkOption
-    mkOptionType
-    mkForce
-    mkMerge
-    mkIf
-    types
-    ;
+  inherit (lib) mkOption mkOptionType;
+  cfg = config.programs.nixvim;
 in
 {
   topLevelModules = [
+    ../modules
     ./modules/output.nix
-    (import ./modules/files.nix (modules pkgs))
-  ] ++ (modules pkgs);
+    ./modules/files.nix
+  ];
 
   helpers = mkOption {
     type = mkOptionType {
@@ -33,9 +22,6 @@ in
   };
 
   configFiles =
-    let
-      cfg = config.programs.nixvim;
-    in
     (lib.mapAttrs' (_: file: lib.nameValuePair "nvim/${file.path}" { text = file.content; }) cfg.files)
     // (lib.mapAttrs' (
       path: content: lib.nameValuePair "nvim/${path}" { text = content; }

wrappers/darwin.nix

@@ -1,8 +1,4 @@
-{
-  modules,
-  self,
-  getHelpers,
-}:
+{ self, getHelpers }:
 {
   pkgs,
   config,
@@ -20,7 +16,7 @@ let
     types
     ;
   helpers = getHelpers pkgs false;
-  shared = import ./_shared.nix { inherit modules helpers; } args;
+  shared = import ./_shared.nix helpers args;
   cfg = config.programs.nixvim;
 in
 {
@@ -31,6 +27,7 @@ in
         shorthandOnlyDefinesConfig = true;
         specialArgs = {
           darwinConfig = config;
+          defaultPkgs = pkgs;
           inherit helpers;
         };
         modules = [ ./modules/darwin.nix ] ++ shared.topLevelModules;

wrappers/hm.nix

@@ -1,8 +1,4 @@
-{
-  modules,
-  self,
-  getHelpers,
-}:
+{ self, getHelpers }:
 {
   pkgs,
   config,
@@ -19,7 +15,7 @@ let
     types
     ;
   helpers = getHelpers pkgs false;
-  shared = import ./_shared.nix { inherit modules helpers; } args;
+  shared = import ./_shared.nix helpers args;
   cfg = config.programs.nixvim;
   files = shared.configFiles // {
     "nvim/init.lua".text = cfg.initContent;
@@ -33,6 +29,7 @@ in
         shorthandOnlyDefinesConfig = true;
         specialArgs = {
           hmConfig = config;
+          defaultPkgs = pkgs;
           inherit helpers;
         };
         modules = [ ./modules/hm.nix ] ++ shared.topLevelModules;

wrappers/modules/files.nix

@@ -1,4 +1,3 @@
-modules:
 {
   pkgs,
   config,
@@ -10,12 +9,15 @@ let
   inherit (lib) types;
   fileModuleType = types.submoduleWith {
     shorthandOnlyDefinesConfig = true;
-    specialArgs.helpers = helpers;
+    specialArgs = {
+      inherit helpers;
+      defaultPkgs = pkgs;
+    };
     modules = [
       (
         { name, config, ... }:
         {
-          imports = modules;
+          imports = [ ../../modules ];
           options.plugin = lib.mkOption {
             type = types.package;
             description = "A derivation with the content of the file in it";

wrappers/nixos.nix

@@ -1,8 +1,4 @@
-{
-  modules,
-  self,
-  getHelpers,
-}:
+{ self, getHelpers }:
 {
   pkgs,
   config,
@@ -20,7 +16,7 @@ let
     types
     ;
   helpers = getHelpers pkgs false;
-  shared = import ./_shared.nix { inherit modules helpers; } args;
+  shared = import ./_shared.nix helpers args;
   cfg = config.programs.nixvim;
   files = shared.configFiles // {
     "nvim/sysinit.lua".text = cfg.initContent;
@@ -34,6 +30,7 @@ in
         shorthandOnlyDefinesConfig = true;
         specialArgs = {
           nixosConfig = config;
+          defaultPkgs = pkgs;
           inherit helpers;
         };
         modules = [ ./modules/nixos.nix ] ++ shared.topLevelModules;

wrappers/standalone.nix

@@ -1,9 +1,5 @@
 default_pkgs:
-{
-  modules,
-  self,
-  getHelpers,
-}:
+{ self, getHelpers }:
 {
   pkgs ? default_pkgs,
   extraSpecialArgs ? { },
@@ -14,23 +10,11 @@ let
   inherit (pkgs) lib;
 
   helpers = getHelpers pkgs _nixvimTests;
-  shared = import ./_shared.nix { inherit modules helpers; } {
+  shared = import ./_shared.nix helpers {
     inherit pkgs lib;
     config = { };
   };
 
-  mkEval =
-    mod:
-    lib.evalModules {
-      modules = [
-        mod
-        { wrapRc = true; }
-      ] ++ shared.topLevelModules;
-      specialArgs = {
-        inherit helpers;
-      } // extraSpecialArgs;
-    };
-
   handleAssertions =
     config:
     let
@@ -44,7 +28,16 @@ let
   mkNvim =
     mod:
     let
-      evaledModule = mkEval mod;
+      evaledModule = lib.evalModules {
+        modules = [
+          mod
+          { wrapRc = true; }
+        ] ++ shared.topLevelModules;
+        specialArgs = {
+          inherit helpers;
+          defaultPkgs = pkgs;
+        } // extraSpecialArgs;
+      };
       config = handleAssertions evaledModule.config;
     in
     (pkgs.symlinkJoin {