From ec760fc6655b2032a38507e937b388e6db67cb03 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Wed, 25 May 2022 19:53:07 +0200
Subject: [PATCH] flake.overlay -> flake.overlays (Nix 2.8)

---
 ChangeLog.md         |  2 ++
 all-modules.nix      |  2 +-
 modules/overlay.nix  | 32 --------------------------------
 modules/overlays.nix | 37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+), 33 deletions(-)
 delete mode 100644 modules/overlay.nix
 create mode 100644 modules/overlays.nix

diff --git a/ChangeLog.md b/ChangeLog.md
index 548f7cb..5fa26b3 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -27,3 +27,5 @@
     ```
 
  - `flake-modules-core` is now called `flake-parts`.
+
+ - `flake.overlay` has been removed in favor of `flake.overlays.default`.
diff --git a/all-modules.nix b/all-modules.nix
index e1e4cf9..ac8a931 100644
--- a/all-modules.nix
+++ b/all-modules.nix
@@ -10,7 +10,7 @@
     ./modules/nixosConfigurations.nix
     ./modules/nixosModules.nix
     ./modules/nixpkgs.nix
-    ./modules/overlay.nix
+    ./modules/overlays.nix
     ./modules/packages.nix
     ./modules/perSystem.nix
   ];
diff --git a/modules/overlay.nix b/modules/overlay.nix
deleted file mode 100644
index d132ac9..0000000
--- a/modules/overlay.nix
+++ /dev/null
@@ -1,32 +0,0 @@
-{ config, lib, flake-parts-lib, ... }:
-let
-  inherit (lib)
-    mkOption
-    types
-    ;
-  inherit (flake-parts-lib)
-    mkSubmoduleOptions
-    ;
-in
-{
-  options = {
-    flake = mkSubmoduleOptions {
-      overlay = mkOption {
-        # uniq should be ordered: https://github.com/NixOS/nixpkgs/issues/147052
-        # also update description when done
-        type = types.uniq (types.functionTo (types.functionTo (types.lazyAttrsOf types.unspecified)));
-        # This eta expansion exists for the sole purpose of making nix flake check happy.
-        apply = f: final: prev: f final prev;
-        default = _: _: { };
-        defaultText = lib.literalExpression or lib.literalExample ''final: prev: {}'';
-        description = ''
-          An overlay.
-
-          Note that this option's type is not mergeable. While overlays can be
-          composed, the order of composition is significant, but the module
-          system does not guarantee deterministic definition ordering.
-        '';
-      };
-    };
-  };
-}
diff --git a/modules/overlays.nix b/modules/overlays.nix
new file mode 100644
index 0000000..9363c82
--- /dev/null
+++ b/modules/overlays.nix
@@ -0,0 +1,37 @@
+{ config, lib, flake-parts-lib, ... }:
+let
+  inherit (lib)
+    mkOption
+    types
+    ;
+  inherit (flake-parts-lib)
+    mkSubmoduleOptions
+    ;
+in
+{
+  options = {
+    flake = mkSubmoduleOptions {
+      overlays = mkOption {
+        # uniq -> ordered: https://github.com/NixOS/nixpkgs/issues/147052
+        # also update description when done
+        type = types.lazyAttrsOf (types.uniq (types.functionTo (types.functionTo (types.lazyAttrsOf types.unspecified))));
+        # This eta expansion exists for the sole purpose of making nix flake check happy.
+        apply = lib.mapAttrs (k: f: final: prev: f final prev);
+        default = { };
+        example = lib.literalExpression or lib.literalExample ''
+          {
+            default = final: prev: {};
+          }
+        '';
+        description = ''
+          An attribute set of overlays.
+
+          Note that the overlays themselves are not mergeable. While overlays
+          can be composed, the order of composition is significant, but the
+          module system does not guarantee sufficiently deterministic
+          definition ordering, across versions and when changing <literal>imports</literal>.
+        '';
+      };
+    };
+  };
+}