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>
This minimal implementation allows `nixpkgs.pkgs` to be defined, but
does not implement evaluating an instance from a pkgsPath when _not_
defined.
The `defaultPkgs` specialArg is dropped in favour of `nixpkgs.pkgs`
being defined. If it's not defined, an assertion is thrown.
In the future, a nixpkgs source path can be supplied, defaulting to the
flake's `inputs.nixpkgs`. Along with other `nixpkgs.*` options, this
will allow a `pkgs` instance to be evaluated within the module eval.
Splits everything that depends on a `pkgs` instance into an optional
attrs, allowing `helpers.nix` to be bootstrapped without `pkgs`.
This required some refactoring:
- `modules.specialArgs` is only available when `pkgs` is used
- `modules.specialArgsWith` now requires `defaultPkgs` be provided
- `builders.*` now have `*With` variants that take `pkgs` as an argument
and a `withPkgs` function that returns the old interface
- Had to define the fixed part of `builders` outside the attrs for now,
to avoid infinite recursion.
- The old `builders` are now deprecated, and print a warning when
evaluated
- `withOptoinalFns` was introduced to merge the optional attrs into the
final lib.
