In nixvim, we recently used the new valueMeta to implement a warning that checks whether a submodule's sub-option is defined.

I was anticipating some breakage for users with an old/outdated nixpkgs revision pre-dating #391544. This seems to be the case for some users, however other users apparently have up-to-date inputs and are still reporting error: attribute 'valueMeta' missing.

Reports are in #3966 and #3960.

The nixvim test suite does not reproduce this in any of its test cases, most of which are module evals. The affected users have not yet provided complete reproducible examples.

One initial hypothesis is that type-merging (not definition merging) could be breaking v2 check+merge? E.g. if users declare programs.nixvim.* submodule options from outside the nixvim submodule, those declarations get merged into the option-type via type-merging. But that is pure conjecture at this point.

Before I dive too deep into investigating and trying to reproduce the issue, I was wondering if hsjobeki , Robert Hensing (roberth) , or anyone else familiar may have some insight or intuition?

Ah, that seems to be it.

A 25.05 (or otherwise pre-v2-checkAndMerge) host configuration importing a nixvim wrapper-module will use that host-configuration's lib as the basis for nixvim's "extended" lib:

https://github.com/nix-community/nixvim/blob/2606dc719488065e735ff0fc622d743566b21ad4/wrappers/_shared.nix#L73-L77

That should probably be changed to freshly import lib from our flake-locked nixpkgs revision, the same as we do when constructing pkgs.