Delegate via a Call instead

Author: scottmcm

compiler/rustc_mir_dataflow/src/elaborate_drops.rs

@@ -747,6 +747,7 @@ where
     ) -> BasicBlock {
         debug!("open_drop_for_array({:?}, {:?})", element_ty, opt_size);
         let tcx = self.tcx();
+        let span = self.source_info.span;
 
         if let Some(0) = opt_size {
             span_bug!(self.source_info.span, "Opened drop for zero-length array of {element_ty:?}")
@@ -758,6 +759,9 @@ where
         let slice_ptr_ty = Ty::new_mut_ptr(tcx, slice_ty);
         let slice_ptr = self.new_temp(slice_ptr_ty);
 
+        let drop_in_place = tcx.require_lang_item(LangItem::DropInPlace, Some(span));
+        let slice_drop_in_place = Operand::function_handle(tcx, drop_in_place, [slice_ty.into()], span);
+
         let unsize_and_drop_block = BasicBlockData {
             statements: vec![
                 self.assign(Place::from(array_ptr), Rvalue::RawPtr(Mutability::Mut, self.place)),
@@ -776,11 +780,19 @@ where
             is_cleanup: self.unwind.is_cleanup(),
             terminator: Some(Terminator {
                 source_info: self.source_info,
-                kind: TerminatorKind::Drop {
-                    place: Place::from(slice_ptr).project_deeper(&[PlaceElem::Deref], tcx),
-                    target: self.succ,
+                kind: TerminatorKind::Call {
+                    func: slice_drop_in_place,
+                    args: Box::new([
+                        Spanned {
+                            node: Operand::Move(Place::from(slice_ptr)),
+                            span,
+                        }
+                    ]),
+                    destination: Place::from(self.new_temp(tcx.types.unit)),
+                    target: Some(self.succ),
                     unwind: self.unwind.into_action(),
-                    replace: false,
+                    call_source: CallSource::Misc,
+                    fn_span: span,
                 },
             }),
         };

tests/mir-opt/slice_drop_shim.core.ptr-drop_in_place.[String;42].AddMovesForPackedDrops.before.mir

@@ -4,6 +4,7 @@ fn std::ptr::drop_in_place(_1: *mut [String; 42]) -> () {
     let mut _0: ();
     let mut _2: *mut [std::string::String; 42];
     let mut _3: *mut [std::string::String];
+    let mut _4: ();
 
     bb0: {
         goto -> bb3;
@@ -20,6 +21,6 @@ fn std::ptr::drop_in_place(_1: *mut [String; 42]) -> () {
     bb3: {
         _2 = &raw mut (*_1);
         _3 = move _2 as *mut [std::string::String] (PointerCoercion(Unsize, Implicit));
-        drop((*_3)) -> [return: bb1, unwind: bb2];
+        _4 = std::ptr::drop_in_place::<[String]>(move _3) -> [return: bb1, unwind: bb2];
     }
 }