error: Validation error: document_signature can only be used on functions and methods
 --> tests/ui/duplicate_document_signature_trait.rs:8:1
  |
8 | #[document_signature]
  | ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this error originates in the attribute macro `document_signature` (in Nightly builds, run with -Z macro-backtrace for more info)
