add_retag: ensure box-to-raw-ptr casts are preserved for Miri

compiler/rustc_mir_transform/src/lib.rs

@@ -529,11 +529,11 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         // AddMovesForPackedDrops needs to run after drop
         // elaboration.
         &add_moves_for_packed_drops::AddMovesForPackedDrops,
-        // `AddRetag` needs to run after `ElaborateDrops`. Otherwise it should run fairly late,
+        // `AddRetag` needs to run after `ElaborateDrops` but before `ElaborateBoxDerefs`. Otherwise it should run fairly late,
         // but before optimizations begin.
+        &add_retag::AddRetag,
         &elaborate_box_derefs::ElaborateBoxDerefs,
         &coroutine::StateTransform,
-        &add_retag::AddRetag,
         &Lint(known_panics_lint::KnownPanicsLint),
     ];
     pm::run_passes_no_validate(tcx, body, passes, Some(MirPhase::Runtime(RuntimePhase::Initial)));