nixos/cups-pdf: fix settings type

[eclairevoyant]

Things done

fixes #438459

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

---

Add a 👍 reaction to pull requests you find important.

[eclairevoyant]

@ofborg test cups-pdf

[Yarny0]

While I don't really understand the freeform system, from looking at https://github.com/NixOS/nixpkgs/blob/dfb2f12e899db4876308eba6d93455ab7da304cd/nixos/doc/manual/development/freeform-modules.section.md , you're right that there is an attrsOf missing here.

This works fine -- nixosTests.cups-pdf passes as is, as well as with the diff from #438459 (comment) applied (tested after cherry-picking the commit onto current nixos-unstable).

[MattSturgeon]

While I don't really understand the freeform system, from looking at dfb2f12/nixos/doc/manual/development/freeform-modules.section.md , you're right that there is an attrsOf missing here.

Yes, "freeform" types must always be an attrs type (either attrsOf or lazyAttrsOf should be fine, IIRC). That's because a submodule is itself another module eval, so its resulting config must be an attrset.