diff --git a/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs b/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs index d2ef648a20ff..367a8c075931 100644 --- a/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs +++ b/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs @@ -92,64 +92,61 @@ pub(super) struct ElaborateBoxDerefs; impl<'tcx> crate::MirPass<'tcx> for ElaborateBoxDerefs { fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { - if let Some(def_id) = tcx.lang_items().owned_box() { - let unique_did = tcx.adt_def(def_id).non_enum_variant().fields[FieldIdx::ZERO].did; + // If box is not present, this pass doesn't need to do anything. + let Some(def_id) = tcx.lang_items().owned_box() else { return }; - let Some(nonnull_def) = tcx.type_of(unique_did).instantiate_identity().ty_adt_def() - else { - span_bug!(tcx.def_span(unique_did), "expected Box to contain Unique") - }; + let unique_did = tcx.adt_def(def_id).non_enum_variant().fields[FieldIdx::ZERO].did; - let nonnull_did = nonnull_def.non_enum_variant().fields[FieldIdx::ZERO].did; + let Some(nonnull_def) = tcx.type_of(unique_did).instantiate_identity().ty_adt_def() else { + span_bug!(tcx.def_span(unique_did), "expected Box to contain Unique") + }; - let patch = MirPatch::new(body); + let nonnull_did = nonnull_def.non_enum_variant().fields[FieldIdx::ZERO].did; - let local_decls = &mut body.local_decls; + let patch = MirPatch::new(body); - let mut visitor = - ElaborateBoxDerefVisitor { tcx, unique_did, nonnull_did, local_decls, patch }; + let local_decls = &mut body.local_decls; - for (block, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() { - visitor.visit_basic_block_data(block, data); - } + let mut visitor = + ElaborateBoxDerefVisitor { tcx, unique_did, nonnull_did, local_decls, patch }; - visitor.patch.apply(body); - - for debug_info in body.var_debug_info.iter_mut() { - if let VarDebugInfoContents::Place(place) = &mut debug_info.value { - let mut new_projections: Option> = None; - - for (base, elem) in place.iter_projections() { - let base_ty = base.ty(&body.local_decls, tcx).ty; - - if let PlaceElem::Deref = elem - && let Some(boxed_ty) = base_ty.boxed_ty() - { - // Clone the projections before us, since now we need to mutate them. - let new_projections = - new_projections.get_or_insert_with(|| base.projection.to_vec()); - - let (unique_ty, nonnull_ty, ptr_ty) = - build_ptr_tys(tcx, boxed_ty, unique_did, nonnull_did); - - new_projections.extend_from_slice(&build_projection( - unique_ty, nonnull_ty, ptr_ty, - )); - new_projections.push(PlaceElem::Deref); - } else if let Some(new_projections) = new_projections.as_mut() { - // Keep building up our projections list once we've started it. - new_projections.push(elem); - } - } + for (block, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() { + visitor.visit_basic_block_data(block, data); + } + + visitor.patch.apply(body); + + for debug_info in body.var_debug_info.iter_mut() { + if let VarDebugInfoContents::Place(place) = &mut debug_info.value { + let mut new_projections: Option> = None; - // Store the mutated projections if we actually changed something. - if let Some(new_projections) = new_projections { - place.projection = tcx.mk_place_elems(&new_projections); + for (base, elem) in place.iter_projections() { + let base_ty = base.ty(&body.local_decls, tcx).ty; + + if let PlaceElem::Deref = elem + && let Some(boxed_ty) = base_ty.boxed_ty() + { + // Clone the projections before us, since now we need to mutate them. + let new_projections = + new_projections.get_or_insert_with(|| base.projection.to_vec()); + + let (unique_ty, nonnull_ty, ptr_ty) = + build_ptr_tys(tcx, boxed_ty, unique_did, nonnull_did); + + new_projections + .extend_from_slice(&build_projection(unique_ty, nonnull_ty, ptr_ty)); + new_projections.push(PlaceElem::Deref); + } else if let Some(new_projections) = new_projections.as_mut() { + // Keep building up our projections list once we've started it. + new_projections.push(elem); } } + + // Store the mutated projections if we actually changed something. + if let Some(new_projections) = new_projections { + place.projection = tcx.mk_place_elems(&new_projections); + } } - } else { - // box is not present, this pass doesn't need to do anything } } }