smallvec::SmallVec::with_capacity(defs.count());
InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind {
GenericParamDefKind::Type { .. } => {
smallvec::SmallVec::with_capacity(defs.count());
InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind {
GenericParamDefKind::Type { .. } => {