Ivan Mincik (imincik):

{
  outputs = { nixpkgs, self }:
    let
      lib = nixpkgs.lib;
      forAllSystems = lib.genAttrs lib.systems.flakeExposed;
    in
    {
      legacyPackages = forAllSystems (system:
        nixpkgs.legacyPackages.${system}.extend (self: super: {
          myHello = self.hello.overrideAttrs (old: {
            name = "my-hello";
          });
        })
      );
    };
}

# Run with `nix-instantiate --eval --strict --json`
let
  pkgs = import <nixpkgs> {};
  inherit (pkgs) lib;

  ifSuccess = value: f:
    let
      result = builtins.tryEval value;
    in
    if result.success then
      f result.value
    else
      "<eval failure>";

  recurse = path: attrs:
    ifSuccess (lib.isDerivation attrs) (isDrv:
      if isDrv then
        ifSuccess (lib.getVersion attrs) (version:
          {
            inherit path version;
          }
        )
      else if lib.isAttrs attrs && (attrs.recurseForDerivations or false) then
        lib.mapAttrs (n: recurse (path ++ [n])) attrs
      else
        null
    );

  mapped = lib.mapAttrs (n: recurse [n]) pkgs;

# WHY does this fail if filterAttrsRecursive is uncommented!?!?
in /*lib.filterAttrsRecursive (path: value: value != null) */mapped

please look at:

• https://github.com/NixOS/nixpkgs/pull/358461

Ivan Mincik (imincik):

{
  outputs = { nixpkgs, self }:
    let
      lib = nixpkgs.lib;
      forAllSystems = lib.genAttrs lib.systems.flakeExposed;

      recurseByDefault = attrs:
        lib.mapAttrs (
          if lib.isDerivation attrs then
            attrs
          else if lib.isAttrs attrs then
            lib.recurseIntoAttrs (recurseByDefault attrs)
          else
            attrs
        ) attrs;

      overlay = self: super: recurseByDefault {
        my.florp = self.hello.overrideAttrs (old: {
          name = "my-florp";
        });
      };
    in
    {
      legacyPackages = forAllSystems (system:
        nixpkgs.legacyPackages.${system}.extend overlay
      );
    };
}

i'm participating virtually from the train 😆 currently trying to figure out how to force logseq to evaluate on aarch64-linux, with this override that has worked on 24.05:

      (pkgs.logseq.overrideAttrs (_: {
          src = lib.mkForce repoFlake.inputs.logseq_0_10_9_aarch64_appimage;
          meta.platforms = lib.mkForce [ "aarch64-linux" ];
      }))

i'm participating virtually from the train 😆 currently trying to figure out how to force logseq to evaluate on aarch64-linux, with this override that has worked on 24.05:

      (pkgs.logseq.overrideAttrs (
        attrs:
        lib.attrsets.recursiveUpdate attrs (
          lib.attrsets.optionalAttrs pkgs.stdenv.isAarch64 {
            src = repoFlake.inputs.logseq_0_10_9_aarch64_appimage;
            meta.platforms = [ "aarch64-linux" ];
          }
        )
      ))

edit: posted the code that actually worked on 24.05

for some reason the src override isn't effective and it still (eagerly?) evaluates the selectSystem function in losgeq.nix:

       … while calling the 'throw' builtin
         at /nix/store/idq1bmwwy9rlkc21hccvx42wlwpxsx1f-source/pkgs/by-name/lo/logseq/package.nix:20:45:
           19|   inherit (stdenv.hostPlatform) system;
           20|   selectSystem = attrs: attrs.${system} or (throw "Unsupported system: ${system}");
             |                                             ^
           21|   suffix = selectSystem {

       error: Unsupported system: aarch64-linux