{"ast_node_type":"other","tokens":[{"end":53,"kind":"keyword","start":0,"text":"///"}]}
/// an attribute may have been mistakenly duplicated.
/// Emit a warning if the item is annotated with the given attribute. This is used to diagnose when
pub(crate) fn warn_on_duplicate_attribute(ecx: &ExtCtxt<'_>, item: &Annotatable, name: Symbol) {