Try `#$(package-source this-package)` in the builder gexp.

Or you can try `(assoc-ref inputs "source")`, but be careful, this is
undocumented behaviour and it may change without notice and break your
recipes.

OT: it's better to ask for help in help-guix@gnu.org :)

jgart <jgart@dismail.de> writes:

> On Sat, 29 Oct 2022 23:05:50 -0500 jgart <jgart@dismail.de> wrote:
>
> For example, nix allows you to reference the source checkout with the $src variable:
>
> https://github.com/NixOS/nixpkgs/blob/nixos-unstable/pkgs/development/compilers/carp/default.nix#L38


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