{"ast_node_type":"impl","tokens":[{"end":67,"kind":"keyword","start":0,"text":")"}]}
    ) -> impl Iterator<Item = (&'tcx FieldDef, RevealedTy<'tcx>)> {
        variant: &'tcx VariantDef,
        let ty::Adt(_, args) = ty.kind() else { bug!() };