Overriding nixpkgs input not working

[Sapp00]

Hi,

I want to use nvim 11.x, so I wanted to make nixCats follow the unstable channel just as I would do for other flakes.

    nixCats = {
      url = "github:BirdeeHub/nixCats-nvim";
      inputs.nixpkgs.follows = "nixpkgs-unstable";
    };

It is also kind of the same as you did in your template: https://github.com/BirdeeHub/nixCats-nvim/blob/main/templates/overriding/flake.nix

Unfortunately, this does not work as I get the following warning during rebuild:
warning: input 'nixCats' has an override for a non-existent input 'nixpkgs'

[BirdeeHub]

nixCats has no flake inputs.

There is no nixpkgs to override.

It uses the nixpkgs you pass where you call the utils.baseBuilder function. So you can just pass it whatever nixpkgs you wish. If you are using the module, the nixpkgs_version option does the same.

[BirdeeHub]

in the overriding template, it is importing an already existing configuration, (the example template's configuration) which does have a nixpkgs.

Note the URL here

nixCats-nvim/templates/overriding/flake.nix

Lines 15 to 16 in e94f31a

	nixCats.url = "github:BirdeeHub/nixCats-nvim?dir=templates/example";
	nixCats.inputs.nixpkgs.follows = "nixpkgs";

And we can see that the flake of the example template does have a nixpkgs

nixCats-nvim/templates/example/flake.nix

Line 25 in e94f31a

nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";

But the base nixCats flake that outputs just the nixCats library with the builder in it has no flake inputs whatsoever.

nixCats-nvim/flake.nix

Lines 1 to 22 in e94f31a

	# Copyright (c) 2023 BirdeeHub
	# Licensed under the MIT license
	{
	description = ''
	# nixCats - nix categories for neovim #
	A neovim package manager written in nix, with normal neovim directory structure,
	easy communication from nix to your neovim configuration,
	and ability to simply categorize dependencies for outputting multiple packages.
	'';
	outputs = _: let
	# everything you will need is in utils.
	utils = import ./utils;
	nixosModule = utils.mkNixosModules {};
	homeModule = utils.mkHomeModules {};
	in {
	inherit utils homeModule nixosModule;
	inherit (utils) templates;
	nixosModules.default = nixosModule;
	homeModules.default = homeModule;
	};
	}

[BirdeeHub]

so yeah if you were wondering how the nixCats-nvim repo has no top level flake.lock, that is why.

utils/default.nix relies only on the builtin functions in nix to import and thus there is no required nixpkgs input.

This is also how it works well with or without flakes despite not using flake-compat

[BirdeeHub]

in the default template, the main builder function is called here

nixCats-nvim/templates/fresh/flake.nix

Lines 206 to 209 in e94f31a

	nixCatsBuilder = utils.baseBuilder luaPath {
	inherit nixpkgs system dependencyOverlays extra_pkg_config;
	} categoryDefinitions packageDefinitions;
	defaultPackage = nixCatsBuilder defaultPackageName;

and in the flakeless one, here

nixCats-nvim/templates/flakeless/default.nix

Line 121 in e94f31a

in utils.baseBuilder luaPath { inherit pkgs; } categoryDefinitions packageDefinitions defaultPackageName

and the modules call it for you.

And here are the docs for it https://nixcats.org/nixCats_utils.html#function-library-nixCats.utils.baseBuilder

That is what defines the pkgs that pkgs.neovim-unwrapped gets pulled from by default (although you can also set neovim-unwrapped settting in your packageDefinitions!)

It is also what controls the pkgs provided to your packageDefinitions and your categoryDefinitions

Unless you pass in a pkgs directly, (in which case, that will be used directly), nixCats will resolve a pkgs for you from the nixpkgs you provide.

In this way, nixCats can work with a variety of nix implementations, such as lix and tvix, and a variety of nixpkgs versions and implementations as well!