| ty::Bound(..)
| ty::Param(_)
| ty::Placeholder(_)
- | ty::Foreign(_)
| ty::Projection(_) => {
// We don't know if these are `~const Drop`, at least
// not structurally... so don't push a candidate.
| ty::FnDef(..)
| ty::FnPtr(_)
| ty::Never
+ | ty::Foreign(_)
| ty::Array(..)
| ty::Slice(_)
| ty::Closure(..)