mkGoEnv cannot find go package in nixpkgs

[iamfraggle]

With the following flake:

{
  description = "A reimplementation of Sandstorm in Go";

  inputs = {
    nixpkgs.url = "nixpkgs/nixos-23.05";
    gomod2nix.url = "github:nix-community/gomod2nix";
  };

  outputs = { self, nixpkgs, gomod2nix }:
    let
      supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
    in
    {
      packages = forAllSystems (system:
        let
          pkgs = nixpkgsFor.${system};
          gonix = (gomod2nix.legacyPackages.${system});
          tempest-src = pkgs.fetchFromGitHub {
            name = "tempest-src";
            owner = "troyjfarrell";
            repo = "tempest";
            rev = "main";
            hash = "sha256-V2+4VXqxbUpTWYrfzxpblzbsJKhAPXe5SoCii3+zxow=";
          };
        in
        {
          tempest = gonix.mkGoEnv {
            pwd = "${tempest-src}";
            modules = ./gomod2nix.toml;
          };
        });

      defaultPackage = forAllSystems (system: self.packages.${system}.tempest);
    };
}

evaluation during nix build fails with:
error: go.mod specified Go version 1.20, but no compatible Go attribute could be found.

Yet the following works in the repl:

nix-repl> :l <nixpkgs>
Added 19222 variables.

nix-repl> :t buildPackages
a set

nix-repl> lib.reverseList (builtins.filter (attr: lib.hasPrefix "go_" attr && lib.versionAtLeast buildPackages.${attr}.version "1.20")(lib.attrNames buildPackages))
[ "go_1_20" ]

[ninjapanzer]

So I don't exactly know why this was complaining since the current go version is 1.23 and I am using 1.22 which according to the comments on https://github.com/nix-community/gomod2nix/blob/master/builder/default.nix#L129

but I did this to resolve the error and make it happy

I added a go attribute pointing to the correct go package for the project

 devShells = forEachSupportedSystem ({ pkgs, gomod2nix }: {
   default = pkgs.mkShell {
     packages = with pkgs; [
       (gomod2nix.mkGoEnv { pwd = ./.; go = go_1_22; })
       gnumake
       gomod2nix
     ];
   };
 });