yeah, there's two things..

1. I have a test box in my fleet that doesn't use lix, partly just to catch cases where something diverges, mostly because I just forgot to add the lix module and discovered that when something broke (one of the experimental features) as a result and so decided to keep it.
2. For all the other hosts, I don't want cppnix there at all, but it is pulled in somewhere and I just haven't bothered chasing down where

In reply to @sofiedotcafe:matrix.org
and make the original somehow not allowed

what I ended up doing, more or less:

{
  nixpkgs.overlays = [
    (f: p: {
      nix = f.lixPackageSets.lix_2_93.lix;

      nixVersions = {
        latest = f.nix;
        stable = f.nix;
      };
    })
  ];

  system.forbiddenDependenciesRegexes = [ "^/nix/store/[a-z0-9]+-nix-[0-9.]+.*" ];
}

of course this will break anything that relies on the c api :|

I'm trying to migrate from the dedicated Lix module to the nixpkgs built-in Lix. IIUC, the manual recommends this:

  nixpkgs.overlays = [
    (final: prev: {
      inherit (prev.lixPackageSets.stable)
        nixpkgs-review
        nix-eval-jobs
        nix-fast-build
        colmena
        ;
    })
  ];

  nix.package = pkgs.lixPackageSets.stable.lix;

However, that throws an infinite recursion for nixpkgs-review. I do have a couple more overlays, but they are not interacting with nixpkgs-review in any obvious way.

What could be the culprit, how to debug?

So, a bit more tinkering revealed that most but not all of the overrides cause the issue:

• nixpkgs-review: causes infinite recursion
• nix-eval-jobs: No problem
• nix-fast-build: causes infinite recursion
• colmena: causes infinite recursion

Here is a minimal repro for playing:

{ pkgs, ... }:

{
  nixpkgs.hostPlatform = "x86_64-linux";

  # TODO debug why this yields infinite recursion
  nixpkgs.overlays = [
    (final: prev: {
      inherit (prev.lixPackageSets.stable)
        nixpkgs-review
        nix-eval-jobs
        nix-fast-build
        colmena
        ;
    })
  ];

  nix.package = pkgs.lixPackageSets.stable.lix;
  environment.systemPackages = with pkgs; [
    nixpkgs-review
    nix-eval-jobs
    nix-fast-build
    colmena
  ];

  boot.isContainer = true;
  fileSystems."/".fsType = "tmpfs";
}