nixpkgs (flake input): 2023-05-06 -> 2023-05-14

```
• Updated input 'nixpkgs-unpatched':
    'github:nixos/nixpkgs/897876e4c484f1e8f92009fd11b7d988a121a4e7' (2023-05-06)
  → 'github:nixos/nixpkgs/0470f36b02ef01d4f43c641bbf07020bcab71bf1' (2023-05-14)
```

flake.lock

@@ -82,11 +82,11 @@
     },
     "nixpkgs-unpatched": {
       "locked": {
-        "lastModified": 1683408522,
-        "narHash": "sha256-9kcPh6Uxo17a3kK3XCHhcWiV1Yu1kYj22RHiymUhMkU=",
+        "lastModified": 1684049129,
+        "narHash": "sha256-7WB9LpnPNAS8oI7hMoHeKLNhRX7k3CI9uWBRSfmOCCE=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "897876e4c484f1e8f92009fd11b7d988a121a4e7",
+        "rev": "0470f36b02ef01d4f43c641bbf07020bcab71bf1",
         "type": "github"
       },
       "original": {

flake.nix

@@ -92,38 +92,31 @@
         nixpkgs = nixpkgs-unpatched;
       };
 
-      nixpkgsCompiledBy = local: nixpkgs.legacyPackages."${local}";
+      nixpkgsCompiledBy = system: nixpkgs.legacyPackages."${system}";
 
-      evalHost = { name, local, target }:
-        let
-          # XXX: we'd prefer to use `nixosSystem = (nixpkgsCompiledBy target).nixos`
-          # but it doesn't propagate config to the underlying pkgs, meaning it doesn't let you use
-          # non-free packages even after setting nixpkgs.allowUnfree.
-          # XXX: patch using the target -- not local -- otherwise the target will
-          # need to emulate the host in order to rebuild!
-          nixosSystem = import ((nixpkgsCompiledBy target).path + "/nixos/lib/eval-config.nix");
-        in
-          (nixosSystem {
-            modules = [
-              (import ./hosts/instantiate.nix { localSystem = local; hostName = name; })
-              self.nixosModules.default
-              self.nixosModules.passthru
-              {
-                nixpkgs.overlays = [
-                  self.overlays.disable-flakey-tests
-                  self.overlays.passthru
-                  self.overlays.pins
-                  self.overlays.pkgs
-                  # self.overlays.optimizations
-                ];
-              }
-              ({ lib, ... }: {
-                nixpkgs.hostPlatform.system = target;
-                # nixpkgs.buildPlatform = local;  # set by instantiate.nix instead
-                # nixpkgs.config.replaceStdenv = { pkgs }: pkgs.ccacheStdenv;
-              })
+      evalHost = { name, local, target }: nixpkgs.lib.nixosSystem {
+        system = target;
+        modules = [
+          (import ./hosts/instantiate.nix { localSystem = local; hostName = name; })
+          self.nixosModules.default
+          self.nixosModules.passthru
+          {
+            nixpkgs.overlays = [
+              self.overlays.disable-flakey-tests
+              self.overlays.passthru
+              self.overlays.pins
+              self.overlays.pkgs
+              # self.overlays.optimizations
             ];
-          });
+          }
+          ({ lib, ... }: {
+            # TODO: does the earlier `system` arg to nixosSystem make its way here?
+            nixpkgs.hostPlatform.system = target;
+            # nixpkgs.buildPlatform = local;  # set by instantiate.nix instead
+            # nixpkgs.config.replaceStdenv = { pkgs }: pkgs.ccacheStdenv;
+          })
+        ];
+      };
     in {
       nixosConfigurations =
         let

nixpatches/flake.nix

@@ -1,5 +1,6 @@
 {
   inputs = {
+    # user is expected to define this from their flake via `inputs.nixpkgs.follows = ...`
     nixpkgs = {};
   };
   outputs = { self, nixpkgs }@inputs:
@@ -16,6 +17,8 @@
         (patchedFlakeFor system).outputs { inherit self; };
     in
     {
+      lib.nixosSystem = args: (patchedFlakeOutputsFor args.system).lib.nixosSystem args;
+
       legacyPackages = builtins.mapAttrs
         (system: _:
           (patchedFlakeOutputsFor system).legacyPackages."${system}"