Rework overlays

There are now two separate overlays:
- backports
- mitigations

flake.nix

@@ -87,7 +87,10 @@
       })
 
       # various temporary fixes that automatically revert
-      (import ./overlays self)
+      self.overlays.mitigations
+
+      # auto backports from nixpkgs unstable
+      self.overlays.backports
 
       inputs.hyprwm-contrib.overlays.default
       inputs.rust-overlay.overlays.default
@@ -284,6 +287,8 @@
     apps = eachSystem (system: import ./pkgs/apps.nix
       { inherit (self.outputs) packages; inherit system; });
 
+    overlays = import ./overlays self;
+
     nixosConfigurations = {
       slab = mkSystem {
         system = "x86_64-linux";

overlays/README.md

@@ -1,9 +1,20 @@
-# backports
-This is a nixpkgs overlay that contains temporary fixes for build failures or
-other issues, usually backported from the nixpkgs master branch. Each package
-defined in this overlay shall automatically disable itself once a certain
-condition is met, such as the upstream package being updated or the nixpkgs
-modification date passing a certain time.
+# Overlays
+This directory contains nixpkgs overlays which each serve some specific purpose.
+
+## backports
+This overlay defines programs that should be unconditionally backported from
+nixpkgs-unstable. Packages backported in this overlay will be built using
+inputs from the current system when possible, as to not unnecessarily increase
+the closure size. This may result in unexpected breakages, as packages in
+nixpkgs-unstable are built and tested against other such packages.
+
+
+## mitigations
+This overlay contains temporary fixes for build failures or other issues,
+usually backported from the nixpkgs master branch. Each package defined in this
+overlay shall automatically disable itself once a certain condition is met,
+such as the upstream package being updated or the nixpkgs modification date
+passing a certain time.
 
 This is in place because I am extremely forgetful; I will almost certainly
 forget to undo a temporary fix later, so this takes care of it for me.

overlays/backports.nix

@@ -0,0 +1,20 @@
+nixfiles: final: prev:
+let
+  pkgs-unstable = import nixfiles.inputs.nixpkgs-unstable { config.allowUnfree = true; inherit (final) system; };
+  inherit (final) callPackage lib electron_28;
+
+  backport = pkg: let
+    inherit (lib) getAttrFromPath;
+    inherit (builtins) getAttr isString;
+    getAttr' = name: attrs: if isString pkg then getAttr name attrs else getAttrFromPath name attrs;
+    oldPkg = getAttr' pkg prev;
+    newPkg = getAttr' pkg pkgs-unstable;
+  in if oldPkg.version == newPkg.version
+    then oldPkg
+    else (callPackage newPkg.override);
+
+in {
+
+  vesktop = backport "vesktop" { };
+  obsidian = backport "obsidian" { electron = final.electron_28; };
+}

overlays/default.nix

@@ -1,25 +1,16 @@
-nixfiles: final: prev:
+nixfiles:
 let
-  inherit (prev) callPackage fetchFromGitHub;
-  inherit (prev.lib) recurseIntoAttrs optionalAttrs;
-  isNewer = ref: ver: (builtins.compareVersions ver ref) == 1;
-
-  # if you can't do version based just make it time based and deal with it in a
-  # month if it's not fixed
-  # 2024-04-10T08:11:11
-  gap-hold = (nixfiles.inputs.nixpkgs-unstable.lastModified <= 1712751071);
-  gimpPlugins-gap = let
-    src = fetchFromGitHub {
-      owner = "Scrumplex";
-      repo = "nixpkgs";
-      rev = "cca25fd345f2c48de66ff0a950f4ec3f63e0420f";
-      hash="sha256-oat4TwOorFevUMZdBFgaQHx/UKqGW7CGMoOHVgQxVdM="; 
-    };
-  in recurseIntoAttrs (callPackage "${src}/pkgs/applications/graphics/gimp/plugins" {});
-in (optionalAttrs gap-hold { gimpPlugins = gimpPlugins-gap; }) //
-  # can't optionalAttrs for version checks because it breaks lazy eval and causes infinite recursion
-  {
-    obsidian = let
-      pkg = final.callPackage "${nixfiles.inputs.nixpkgs-unstable}/pkgs/applications/misc/obsidian" { electron = final.electron_28; };
-    in if isNewer "1.4.16" prev.obsidian.version then prev.obsidian else pkg;
-  }
+  inherit (nixfiles.inputs.nixpkgs) lib;
+  # this name is awful. maybe i don't know anything about functional
+  # programming or something, but the naming isn't very self explanatory
+  # - why is it "compose" instead of "combine"
+  # - why is it "extensions" instead of "overlays"
+  inherit (lib) composeManyExtensions;
+in rec {
+  backports = import ./backports.nix nixfiles;
+  mitigations = import ./mitigations.nix nixfiles;
+  default = composeManyExtensions [
+    backports
+    mitigations
+  ];
+}

overlays/mitigations.nix

@@ -0,0 +1,25 @@
+nixfiles: final: prev:
+let
+  inherit (prev) callPackage fetchFromGitHub;
+  inherit (prev.lib) recurseIntoAttrs optionalAttrs;
+  isNewer = ref: ver: (builtins.compareVersions ver ref) == 1;
+
+  # if you can't do version based just make it time based and deal with it in a
+  # month if it's not fixed
+  # 2024-04-10T08:11:11
+  gap-hold = (nixfiles.inputs.nixpkgs-unstable.lastModified <= 1712751071);
+  gimpPlugins-gap = let
+    src = fetchFromGitHub {
+      owner = "Scrumplex";
+      repo = "nixpkgs";
+      rev = "cca25fd345f2c48de66ff0a950f4ec3f63e0420f";
+      hash="sha256-oat4TwOorFevUMZdBFgaQHx/UKqGW7CGMoOHVgQxVdM="; 
+    };
+  in recurseIntoAttrs (callPackage "${src}/pkgs/applications/graphics/gimp/plugins" {});
+in (optionalAttrs gap-hold { gimpPlugins = gimpPlugins-gap; })
+  # # can't optionalAttrs for version checks because it breaks lazy eval and causes infinite recursion
+  # // {
+  #   obsidian = let
+  #     pkg = final.callPackage "${nixfiles.inputs.nixpkgs-unstable}/pkgs/applications/misc/obsidian" { electron = final.electron_28; };
+  #   in if isNewer "1.4.16" prev.obsidian.version then prev.obsidian else pkg;
+  # }