modules/keymaps: fix lua option deprecation warning

[MattSturgeon]

The deprecation warning for the keymap-submocule lua option relied on getSubOptions, however this is fundamentally flawed because that function uses a different module eval from the one that merges submodule definitions.

Since definitions are not used by getSubOptions, options.lua.isDefined will never be true.

Instead, we have two choices:

1. Add a luaIsDefined option to the keymap submodule
2. Use the new v2 merge's valueMeta to access the actual module eval

In this PR I've implemented option 2, and added tests to ensure the warning actually works. Actually testing that warnings and deprecated options work as expected is important, as demonstrated by this one being broken so long without us noticing.

Since the warning will not have been shown to any users, I've pushed back the "will be removed after" epoch. (Sadly, I started working on this because I was hoping to delete all the deprecated lua option code... Then I noticed it was fundamentally flawed).

[GaetanLepage]

Good catch!!!

[VvSsNPk]

… while evaluating the option system.build.toplevel':

   … while evaluating definitions from `/nix/store/hr5pl7m833kkr0zv98iydy7mxyl10qld-source/nixos/modules/system/activation/top-level.nix':

   … while evaluating the option `warnings':

   … while evaluating definitions from `/nix/store/a4la088hi5id7sw77gy9zdvwn83dgczz-source/nixos/common.nix':

   … while evaluating the option `home-manager.users.royaleinstein.warnings':

   … while evaluating definitions from `/nix/store/ykn2jzkrv3k7zcafjkyddyj31bd6f9bx-source/wrappers/_shared.nix':

   … while evaluating the option `home-manager.users.royaleinstein.programs.nixvim.warnings':

   … while evaluating definitions from `/nix/store/ykn2jzkrv3k7zcafjkyddyj31bd6f9bx-source/modules/keymaps.nix':

   (stack trace truncated; use '--show-trace' to show the full, detailed trace)

   error: attribute 'valueMeta' missing
   at /nix/store/ykn2jzkrv3k7zcafjkyddyj31bd6f9bx-source/modules/keymaps.nix:61:15:
       60|             [
       61|               options.keymaps.valueMeta.list
         |               ^
       62|               (lib.concatMap (ev: ev.list) (lib.attrValues options.keymapsOnEvents.valueMeta.attrs))

~`

Getting this error when updating nixvim, feel like this error has something to do with this change

[MattSturgeon]

Thanks for reporting!

Do you have a really old nixpkgs revision somewhere?

If lib is being constructed from a nixpkgs revision that doesn't have NixOS/nixpkgs#391544, then this error is expected.

We can handle that edge-case better, though 🤔

[AleAndForCode]

Thanks for reporting!

Do you have a really old nixpkgs revision somewhere?

If lib is being constructed from a nixpkgs revision that doesn't have NixOS/nixpkgs#391544, then this error is expected.

We can handle that edge-case better, though 🤔

I've just updated my flake inputs and got the same error for latest both stable and unstable nixpkgs

[SJ-Fang23]

Same here, In my case, Nixvim is following NixOS-Unstable branch of the NixPkgs. Maybe the ValueMeta update hasn't made it way into downstream NixOS-Unstable branch?