From 30bddfe65b9f19d12730d6e77e8dd94fafd41b72 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Wed, 4 Jan 2023 20:10:09 +0100
Subject: [PATCH] easyOverlay: Support pkgs.system as a fallback

This is required for `exportOverlays` in `digga`, which passes a fake
`pkgs` that doesn't have a `pkgs.stdenv`, but does have a `pkgs.system`.
---
 extras/easyOverlay.nix | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/extras/easyOverlay.nix b/extras/easyOverlay.nix
index 306836a..fbb1b03 100644
--- a/extras/easyOverlay.nix
+++ b/extras/easyOverlay.nix
@@ -44,7 +44,12 @@ in
   config = {
     flake.overlays.default = final: prev:
       let
-        system = prev.stdenv.hostPlatform.system;
+        system =
+          prev.stdenv.hostPlatform.system or (
+            prev.system or (
+              throw "Could not determine the `hostPlatform` of Nixpkgs. Was this overlay loaded as a Nixpkgs overlay, or was it loaded into something else?"
+            )
+          );
         perSys = (getSystem system).extendModules {
           modules = [
             {