Import the overlay multiple times should raise a clear error #486
Description
For some reason I did this in my config back when setting my deck up in early 2024.
imports = [ "${jovian}/modules" ];
nixpkgs.overlays = [ jovian.overlays.default ];After 414e29f this led to multiple patch applications and a subsequent build failure.
nix-repl> nixosConfigurations.artemis.pkgs.gamescope.patches
[
/nix/store/593xvgv994xlkm5mb7w4p1xxnzrs9wv6-source/pkgs/by-name/ga/gamescope/scripts-path.patch
/nix/store/593xvgv994xlkm5mb7w4p1xxnzrs9wv6-source/pkgs/by-name/ga/gamescope/shaders-path.patch
/nix/store/593xvgv994xlkm5mb7w4p1xxnzrs9wv6-source/pkgs/by-name/ga/gamescope/gamescopereaper.patch
/nix/store/p2c1m7bzxnbp7fkjap2xmfdbpjsgxkjc-source/pkgs/gamescope/32bit-crash-fix.patch
/nix/store/p2c1m7bzxnbp7fkjap2xmfdbpjsgxkjc-source/pkgs/gamescope/32bit-crash-fix.patch
]
The solution is to drop the overlay, since it is already configured via
Jovian-NixOS/modules/jovian/overlay.nix
Lines 4 to 6 in b217d3a
Apparently I'm not the first person to run into this non-obvious failure mode, so Samuel suggested creating a sentinel package that would cause a clear error when the overlay gets applied multiple times.
Affected configs on GitHub:
@matt1432 https://github.com/matt1432/nixos-configs/blob/7d7180b0aa13f750a3a57efd98708b306a95cb2c/configurations/bbsteamie/hardware-configuration.nix#L11
@wozeparrot https://github.com/wozeparrot/solarsys/blob/926d2612d1ddafdaf76d772cb778998c9be0d4dd/flake.nix#L390
@vivlim https://github.com/vivlim/nix-deck/blob/02e906353cdde08495a3adb6b16aa79427748345/flake.nix#L42
@wkral https://github.com/wkral/home-nix/blob/b8f52d34b9b83e567a98efbd2f9f6c2ebea0dc68/hosts/deck/configuration.nix#L11
@sg-qwt https://github.com/sg-qwt/nixos/blob/70ab7a06bf51b0bc31fb52291a2c7770d4f34b4c/flake.nix#L106
Remove the jovian overlay!