From 4973006da0243ed36e3fa5ac2fe52e582c672b0b Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <silvan.mosberger@tweag.io>
Date: Mon, 25 Nov 2024 16:58:58 +0100
Subject: [PATCH] Hacking together with @hsjobeki

---
 lib/modules.nix | 23 ++++++++++++++++++++---
 lib/types.nix   | 18 +++++++++++-------
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/lib/modules.nix b/lib/modules.nix
index 855ffaf25ed81e..bd11ce3904937c 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -751,9 +751,26 @@ let
           t' = opt.options.type;
           mergedType = t.typeMerge t'.functor;
           typesMergeable = mergedType != null;
-          typeSet = if (bothHave "type") && typesMergeable
-                       then { type = mergedType; }
-                       else {};
+
+          addDeprecatedWrapped = t:
+            t // {
+              functor = t.functor // {
+                wrapped = t.functor.wrappedDeprecationMessage {
+                  inherit loc;
+                };
+              };
+            };
+
+          typeSet =
+            if (bothHave "type") && typesMergeable then
+              { type = addDeprecatedWrapped mergedType; }
+            else if opt.options.type ? functor.wrappedDeprecationMessage then
+              {
+                type = addDeprecatedWrapped opt.options.type;
+              }
+            else
+              {};
+
           bothHave = k: opt.options ? ${k} && res ? ${k};
       in
       if bothHave "default" ||
diff --git a/lib/types.nix b/lib/types.nix
index a286f16227a0f3..ea6de3ee4fd097 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -86,6 +86,8 @@ rec {
     let mergedWrapped = f.wrapped.typeMerge f'.wrapped.functor;
         mergedPayload = f.binOp f.payload f'.payload;
 
+        mergedDeprecatedWrapped = f.wrapped.elemType.typeMerge f'.wrapped.elemType.functor;
+
         hasPayload = assert (f'.payload != null) == (f.payload != null); f.payload != null;
         hasWrapped = assert (f'.wrapped != null) == (f.wrapped != null); f.wrapped != null;
     in
@@ -95,7 +97,9 @@ rec {
     else
 
     if hasPayload then
-      if hasWrapped then
+      if f ? wrappedDeprecationMessage || ! hasWrapped then
+        if mergedPayload == null then null else f.type mergedPayload
+      else
         # Has both wrapped and payload
         throw ''
           Type ${f.name} defines both `functor.payload` and `functor.wrapped` at the same time, which is not supported.
@@ -104,9 +108,6 @@ rec {
 
           If your code worked before remove `functor.payload` from the type definition.
         ''
-      else
-        # Has payload
-        if mergedPayload == null then null else f.type mergedPayload
     else
       if hasWrapped then
         # Has wrapped
@@ -592,7 +593,11 @@ rec {
     lazyAttrsOf = elemType: attrsWith { inherit elemType; lazy = true; };
 
     # base type for lazyAttrsOf and attrsOf
-    attrsWith = {
+    attrsWith =
+      let
+        warnWrapped = loc: lib.warn "Using wrapped, use nestedTypes.elemType instead ${showOption loc}";
+      in
+    {
       elemType,
       lazy ? false,
     }:
@@ -630,8 +635,7 @@ rec {
       getSubModules = elemType.getSubModules;
       substSubModules = m: attrsWith { elemType = elemType.substSubModules m; inherit lazy; };
       functor = defaultFunctor "attrsWith" // {
-        # TODO: This breaks stuff
-        # wrapped = elemType;
+        wrappedDeprecationMessage = { loc }: warnWrapped loc elemType;
         payload = {
           # Important!: Add new function attributes here in case of future changes
           inherit elemType lazy;