Auto merge of #134625 - compiler-errors:unsafe-binders-ty, r=oli-obk

Begin to implement type system layer of unsafe binders

Mostly TODOs, but there's a lot of match arms that are basically just noops so I wanted to split these out before I put up the MIR lowering/projection part of this logic.

r? oli-obk

Tracking:

- https://github.com/rust-lang/rust/issues/130516

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -932,7 +932,8 @@ fn try_write_constant<'tcx>(
         | ty::Closure(..)
         | ty::CoroutineClosure(..)
         | ty::Coroutine(..)
-        | ty::Dynamic(..) => throw_machine_stop_str!("unsupported type"),
+        | ty::Dynamic(..)
+        | ty::UnsafeBinder(_) => throw_machine_stop_str!("unsupported type"),
 
         ty::Error(_) | ty::Infer(..) | ty::CoroutineWitness(..) => bug!(),
     }

compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs

@@ -285,7 +285,9 @@ fn ty_dtor_span<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<Span> {
         | ty::Placeholder(_)
         | ty::Infer(_)
         | ty::Slice(_)
-        | ty::Array(_, _) => None,
+        | ty::Array(_, _)
+        | ty::UnsafeBinder(_) => None,
+
         ty::Adt(adt_def, _) => {
             let did = adt_def.did();
             let try_local_did_span = |did: DefId| {