| /// A trait implemented for all `X<'a>` types that can be safely and |
| /// efficiently converted to `X<'tcx>` as long as they are part of the |
| /// provided `TyCtxt<'tcx>`. |
| /// This can be done, for example, for `Ty<'tcx>` or `GenericArgsRef<'tcx>` |
| /// by looking them up in their respective interners. |
| /// |
| /// However, this is still not the best implementation as it does |
| /// need to compare the components, even for interned values. |
| /// It would be more efficient if `TypedArena` provided a way to |
| /// determine whether the address is in the allocated range. |
| /// |
| /// `None` is returned if the value or one of the components is not part |
| /// of the provided context. |
| /// For `Ty`, `None` can be returned if either the type interner doesn't |
| /// contain the `TyKind` key or if the address of the interned |
| /// pointer differs. The latter case is possible if a primitive type, |
| /// e.g., `()` or `u8`, was interned in a different context. |
| pub trait Lift<I>: std::fmt::Debug { |
| type Lifted: std::fmt::Debug; |
| fn lift_to_tcx(self, tcx: I) -> Option<Self::Lifted>; |
| } |
