lib/types: types.coercedTo deprecate functor.wrapped in favor of functor.payload.elemType

doc/release-notes/rl-2505.section.md

@@ -78,6 +78,7 @@
     - `lib.types.unique` and `lib.types.uniq`
     - `lib.types.nullOr`
     - `lib.types.functionTo`
+    - `lib.types.coercedTo`
 
 - Plasma 5 and Qt 5 based versions of associated software are deprecated in NixOS 25.05, and will be removed in NixOS 25.11. Users are encouraged to upgrade to Plasma 6.
 

lib/tests/modules.sh

@@ -434,6 +434,12 @@ NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribu
 NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.functionTo.type.nestedTypes.elemType.functor.wrapped ./deprecated-wrapped.nix
 NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.mergedFunctionTo.type.nestedTypes.elemType.functor.wrapped ./deprecated-wrapped.nix
 
+# coercedTo
+# Note: test 'nestedTypes.finalType' and 'nestedTypes.coercedType'
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.nestedTypes.finalType.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.nestedTypes.coercedType.functor.wrapped ./deprecated-wrapped.nix
+
 # Even with multiple assignments, a type error should be thrown if any of them aren't valid
 checkConfigError 'A definition for option .* is not of type .*' \
   config.value ./declare-int-unsigned-value.nix ./define-value-list.nix ./define-value-int-positive.nix

lib/tests/modules/deprecated-wrapped.nix

@@ -9,6 +9,7 @@ let
     unique
     nullOr
     functionTo
+    coercedTo
     ;
 in
 {
@@ -43,13 +44,18 @@ in
         options.mergedNullOr = mkOption {
           type = nullOr (listOf types.str);
         };
-        # nullOr
+        # functionTo
         options.functionTo = mkOption {
           type = functionTo (listOf types.str);
         };
         options.mergedFunctionTo = mkOption {
           type = functionTo (listOf types.str);
         };
+        # coercedTo
+        # Note: coercedTo is a non-mergeable option-type
+        options.coercedTo = mkOption {
+          type = coercedTo (listOf types.str) lib.id (listOf types.str);
+        };
       }
     )
     # Module B

lib/types.nix

@@ -75,6 +75,7 @@ let
   # Note that individual attributes can be overriden if needed.
   elemTypeFunctor = name: { elemType, ... }@payload: {
     inherit name payload;
+    wrappedDeprecationMessage = makeWrappedDeprecationMessage payload;
     type    = outer_types.types.${name};
     binOp   = a: b:
       let
@@ -85,10 +86,10 @@ let
           null
         else
           { elemType = merged; };
-    wrappedDeprecationMessage = { loc }: lib.warn ''
-      The deprecated `${lib.optionalString (loc != null) "type."}functor.wrapped` attribute ${lib.optionalString (loc != null) "of the option `${showOption loc}` "}is accessed, use `${lib.optionalString (loc != null) "type."}nestedTypes.elemType` instead.
-    '' payload.elemType;
   };
+  makeWrappedDeprecationMessage = payload: { loc }: lib.warn ''
+    The deprecated `${lib.optionalString (loc != null) "type."}functor.wrapped` attribute ${lib.optionalString (loc != null) "of the option `${showOption loc}` "}is accessed, use `${lib.optionalString (loc != null) "type."}nestedTypes.elemType` instead.
+  '' payload.elemType;
 
 
   outer_types =
@@ -1163,7 +1164,9 @@ rec {
         getSubModules = finalType.getSubModules;
         substSubModules = m: coercedTo coercedType coerceFunc (finalType.substSubModules m);
         typeMerge = t: null;
-        functor = (defaultFunctor name) // { wrapped = finalType; };
+        functor = (defaultFunctor name) // {
+          wrappedDeprecationMessage = makeWrappedDeprecationMessage { elemType = finalType; };
+        };
         nestedTypes.coercedType = coercedType;
         nestedTypes.finalType = finalType;
       };