lib.packagesFromDirectoryRecursive: reject unknown arguments

see [discussion](NixOS#270537 (comment))

lib/filesystem.nix

@@ -311,7 +311,7 @@ in
       newScope? :: AttrSet -> scope,
       directory :: Path,
       recurseIntoDirectory? :: (args -> AttrSet) -> args -> AttrSet,
-      ...
+      recurseArgs? :: Any
     }) -> AttrSet
     ```
 
@@ -349,6 +349,9 @@ in
       ```
       :::
 
+    `recurseArgs`
+    : Optional argument, which can be hold data used by `recurseIntoDirectory`
+
     # Examples
     :::{.example}
     ## Basic use of `lib.packagesFromDirectoryRecursive`
@@ -421,8 +424,11 @@ in
     in
     {
       callPackage,
+      newScope ? throw "lib.packagesFromDirectoryRecursive: newScope wasn't passed in args",
       directory,
-      # recurseIntoDirectory can modify the function used when processing directory entries; see nixdoc above
+      # recurseIntoDirectory can modify the function used when processing directory entries
+      #  and recurseArgs can (optionally) hold data for its use ; see nixdoc above
+      recurseArgs ? throw "lib.packagesFromDirectoryRecursive: recurseArgs wasn't passed in args",
       recurseIntoDirectory ?
         if args ? newScope then
           # `processDir` is the same function as defined above
@@ -442,7 +448,6 @@ in
         else
           # otherwise, no modification is necessary
           id,
-      ...
     }@args:
     let
       defaultPath = append directory "package.nix";

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

@@ -311,6 +311,10 @@
   - [`lib.types.enum`](https://nixos.org/manual/nixos/unstable/#sec-option-types-basic): Previously the `functor.payload` was the list of enum values directly. Now it is an attribute set containing the values in the `values` attribute.
   - [`lib.types.separatedString`](https://nixos.org/manual/nixos/unstable/#sec-option-types-string): Previously the `functor.payload` was the seperator directly. Now it is an attribute set containing the seperator in the `sep` attribute.
 
+- [`lib.packagesFromDirectoryRecursive`] now rejects unknown arguments, and applies [`lib.recurseIntoAttrs`] when recursing into a directory.
+  [`lib.packagesFromDirectoryRecursive`]: https://nixos.org/manual/nixpkgs/stable/#function-library-lib.filesystem.packagesFromDirectoryRecursive
+  [`lib.recurseIntoAttrs`]: https://nixos.org/manual/nixpkgs/stable/#function-library-lib.attrsets.recurseIntoAttrs
+
 ### Other notable changes {#sec-release-25.05-lib-notable-changes}
 
-- `lib.packagesFromDirectoryRecursive` can now construct nested scopes matching the directory tree passed as input.
+- [`lib.packagesFromDirectoryRecursive`] can now construct nested scopes matching the directory tree passed as input.