Function clean_fn_or_proc_macro 

fn clean_fn_or_proc_macro<'tcx>(
    item: &Item<'tcx>,
    sig: &FnSig<'tcx>,
    generics: &Generics<'tcx>,
    body_id: BodyId,
    name: &mut Symbol,
    cx: &mut DocContext<'tcx>,
) -> ItemKind