gst_all_1: use newScope to create package set

[B4dM4n]

Motivation for this change

Overriding gst_all_1.gstreamer is a pain, because it is contained in a rec set and manually passes itself and other dependencies from the set directly to dependent packages. So in order to propagate a overwritten gstreamer to it's dependent packages an overlay like this is required:

final: prev: {
  gst_all_1 = prev.gst_all_1 // rec {
    gstreamer = prev.gst_all_1.gstreamer.overrideAttrs (old: { ... });

    gst-plugins-base = prev.gst_all_1.gst-plugins-base.override { inherit gstreamer; };

    gst-plugins-good = prev.gst_all_1.gst-plugins-good.override { inherit gst-plugins-base; };

    ...
  };
}

This overlay would also miss new packages in the set depending on any of the current packages.

Using lib.makeScope would allow to conveniently override any package in the set and ensure it is used in all dependent packages:

final: prev: {
  gst_all_1 = prev.gst_all_1.overrideScope' (final: prev: {
    gstreamer = prev.gstreamer.overrideAttrs (old: { ... });
  });
}

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[FRidh]

I think we should avoid this pattern in package sets: using the callPackage from a different scope breaks composition. In these cases it is in my opinion much better to pass in the subpackage set.

[FRidh]

Related RFC NixOS/rfcs#83.

[jtojnar]

Alternately, we could move those packages to top-level. But scoping sound good to me too. cc @worldofpeace

[worldofpeace]

@jtojnar I think some time in the past came upon that the need for a gst_all_1 has passed. It was really confusing to have old versions of gst as the top level attributes. I would be in favor of moving them all to top-level and keeping gst_all_1 as an alias.

[stale]

I marked this as stale due to inactivity. → More info

[Princemachiavelli]

I think #131295 fixed this by removing rec. I'm able to easily override gstreamer with the following overlay (there might be an even better way but this makes sense to me):

final: prev: {
  gst_all_1 = prev.gst_all_1 // {
      gstreamer = prev.gst_all_1.gstreamer.overrideAttrs( prev: {
        pname= prev.pname + "-foo";
      });
  };
}

Checking gst_all_1.gst-plugins-base shows that the override to gstreamer is pulled in without having to manual pass the new `gstreamer.