Merge 2c9202a48b into cb7ff874e2

`vim.undoFile.enable` and `vim.undoFile.path` can be used to manipulate whether undofile will be enabled, and the location if it is enabled.

modules/neovim/init/basic.nix

@@ -3,12 +3,11 @@
   lib,
   ...
 }: let
-  inherit (lib.options) mkOption mkEnableOption literalExpression literalMD;
+  inherit (lib.options) mkOption mkEnableOption literalExpression;
   inherit (lib.strings) optionalString;
-  inherit (lib.types) enum bool str int either;
-  inherit (lib.generators) mkLuaInline;
+  inherit (lib.types) enum bool str int nullOr either;
   inherit (lib.nvim.dag) entryAfter;
-  inherit (lib.nvim.lua) toLuaObject;
+  inherit (lib.nvim.lua) toLuaObject mkLuaInline;
   inherit (lib.nvim.types) luaInline;
 
   cfg = config.vim;
@@ -162,21 +161,31 @@ in {
     };
 
     undoFile = {
-      enable = mkEnableOption "undofile for Neovim";
+      enable = mkEnableOption ''
+        undofile for Neovim.
+
+        ::: {.warning}
+        [{option}`vim.undoFile.path`](#opt-vim.undoFile.path) **must** be set to a valid
+        path for this option to have any effect.
+        :::
+      '';
+
       path = mkOption {
-        type = either str luaInline;
-        default = mkLuaInline "vim.fn.stdpath('state') .. '/nvf/undo'";
-        defaultText = literalMD ''
-          ```nix
-          mkLuaInline "vim.fn.stdpath('state') .. '/nvf/undo'"
-          ```
+        type = nullOr (either str luaInline);
+        default = null;
+        example = "os.getenv('XDG_DATA_HOME') .. '/nvf/undo'";
+        description = ''
+          Path to the file in which undo history will be saved. Must
+          an absolute path in a world-writable directory such as
+          {file}`~/.local/share`.
+
+          ::: {.tip}
+          You can use use variable substitution as you normally would in Neovim to
+          pick directories that conform with XDG spec. **nvf**, by, default creates
+          {file}`$XDG_DATA_HOME/nvf` - which you may choose to use for storing
+          state such as the undofile.
+          :::
         '';
-        example = literalMD ''
-          ```nix
-          mkLuaInline "os.getenv('XDG_DATA_HOME') .. '/nvf/undo'"
-          ```
-        '';
-        description = "Path to the file in which undo history will be saved";
       };
     };
   };
@@ -293,5 +302,16 @@ in {
         vim.o.ignorecase = false
       ''}
     '';
+
+    assertions = [
+      {
+        assertion = cfg.undoFile.enable -> cfg.undoFile.path != null;
+        message = ''
+          `vim.undoFile.enable` is set to true, but `vim.undoFile.path` is not set
+          as a valid path. Please set `vim.undoFile.path` to a valid path, or disable
+          the undoFile feature.
+        '';
+      }
+    ];
   };
 }