From 6b0c5d594ac88e7765c97deeda10c5b6e812f7a7 Mon Sep 17 00:00:00 2001
From: Matt Sturgeon <matt@sturgeon.me.uk>
Date: Fri, 27 Sep 2024 01:02:57 +0100
Subject: [PATCH] lib/modules: assert that `specialArgs` has a valid `lib`
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End-users have ran into issues before when attempting to re-use a `lib`
from elsewhere in nixvim's configuration.

If a `lib` without the `nixvim` extension is used, this assertion will
inform the user that this isn't supported.

In the future we can also provide better ways for end-users to overlay
their own lib with nixvim's extensions, but this is not yet implemented.

Co-authored-by: Gaétan Lepage <33058747+GaetanLepage@users.noreply.github.com>
---
 lib/modules.nix | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/modules.nix b/lib/modules.nix
index 897b6890..1da6f337 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -23,6 +23,11 @@ in
     # NOTE: this argument was always marked as experimental
     assert lib.assertMsg (!args ? "check")
       "`evalNixvim`: passing `check` is no longer supported. Checks are now done when evaluating `config.build.package` and can be avoided by using `config.build.packageUnchecked` instead.";
+    # Ensure a suitable `lib` is used
+    # TODO: offer a lib overlay that end-users could use to apply nixvim's extensions to their own `lib`
+    assert lib.assertMsg (extraSpecialArgs ? lib -> extraSpecialArgs.lib ? nixvim) ''
+      Nixvim requires a lib that includes some custom extensions, however the `lib` from `specialArgs` does not have a `nixvim` attr.
+      Remove `lib` from nixvim's `specialArgs` or ensure you apply nixvim's extensions to your `lib`.'';
     lib.evalModules {
       modules = [ ../modules/top-level ] ++ modules;
       specialArgs = {