Rollup merge of rust-lang#56165 - RalfJung:drop-glue-type, r=eddyb,nikomatsakis

drop glue takes in mutable references, it should reflect that in its type

When drop glue begins, it should retag, like all functions taking references do. But to do that, it needs to take the reference at a proper type: `&mut T`, not `*mut T`.

Failing to retag can mean that the memory the reference points to remains frozen, and `EscapeToRaw` on a frozen location is a NOP, meaning later mutations cause a Stacked Borrows violation.

Cc @nikomatsakis @gankro because Stacked Borrows
Cc @eddyb for the changes to miri argument passing (the intention is to allow passing `*mut [u8]` when `&mut [u8]` is expected and vice versa)

Author: pietroalbini

src/libcore/ptr.rs

@@ -189,12 +189,22 @@ pub use intrinsics::write_bytes;
 /// i.e., you do not usually have to worry about such issues unless you call `drop_in_place`
 /// manually.
 #[stable(feature = "drop_in_place", since = "1.8.0")]
+#[inline(always)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    real_drop_in_place(&mut *to_drop)
+}
+
+// The real `drop_in_place` -- the one that gets called implicitly when variables go
+// out of scope -- should have a safe reference and not a raw pointer as argument
+// type.  When we drop a local variable, we access it with a pointer that behaves
+// like a safe reference; transmuting that to a raw pointer does not mean we can
+// actually access it with raw pointers.
 #[lang = "drop_in_place"]
 #[allow(unconditional_recursion)]
-pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+unsafe fn real_drop_in_place<T: ?Sized>(to_drop: &mut T) {
     // Code here does not matter - this is replaced by the
     // real drop glue by the compiler.
-    drop_in_place(to_drop);
+    real_drop_in_place(to_drop)
 }
 
 /// Creates a null raw pointer.

src/librustc_mir/interpret/terminator.rs

@@ -182,20 +182,28 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
     }
 
     fn check_argument_compat(
+        rust_abi: bool,
         caller: TyLayout<'tcx>,
         callee: TyLayout<'tcx>,
     ) -> bool {
         if caller.ty == callee.ty {
             // No question
             return true;
         }
+        if !rust_abi {
+            // Don't risk anything
+            return false;
+        }
         // Compare layout
         match (&caller.abi, &callee.abi) {
+            // Different valid ranges are okay (once we enforce validity,
+            // that will take care to make it UB to leave the range, just
+            // like for transmute).
             (layout::Abi::Scalar(ref caller), layout::Abi::Scalar(ref callee)) =>
-                // Different valid ranges are okay (once we enforce validity,
-                // that will take care to make it UB to leave the range, just
-                // like for transmute).
                 caller.value == callee.value,
+            (layout::Abi::ScalarPair(ref caller1, ref caller2),
+             layout::Abi::ScalarPair(ref callee1, ref callee2)) =>
+                caller1.value == callee1.value && caller2.value == callee2.value,
             // Be conservative
             _ => false
         }
@@ -204,22 +212,22 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
     /// Pass a single argument, checking the types for compatibility.
     fn pass_argument(
         &mut self,
-        skip_zst: bool,
+        rust_abi: bool,
         caller_arg: &mut impl Iterator<Item=OpTy<'tcx, M::PointerTag>>,
         callee_arg: PlaceTy<'tcx, M::PointerTag>,
     ) -> EvalResult<'tcx> {
-        if skip_zst && callee_arg.layout.is_zst() {
+        if rust_abi && callee_arg.layout.is_zst() {
             // Nothing to do.
             trace!("Skipping callee ZST");
             return Ok(());
         }
         let caller_arg = caller_arg.next()
             .ok_or_else(|| EvalErrorKind::FunctionArgCountMismatch)?;
-        if skip_zst {
+        if rust_abi {
             debug_assert!(!caller_arg.layout.is_zst(), "ZSTs must have been already filtered out");
         }
         // Now, check
-        if !Self::check_argument_compat(caller_arg.layout, callee_arg.layout) {
+        if !Self::check_argument_compat(rust_abi, caller_arg.layout, callee_arg.layout) {
             return err!(FunctionArgMismatch(caller_arg.layout.ty, callee_arg.layout.ty));
         }
         // We allow some transmutes here
@@ -319,7 +327,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
                     // Figure out how to pass which arguments.
                     // We have two iterators: Where the arguments come from,
                     // and where they go to.
-                    let skip_zst = match caller_abi {
+                    let rust_abi = match caller_abi {
                         Abi::Rust | Abi::RustCall => true,
                         _ => false
                     };
@@ -344,7 +352,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
                         };
                     // Skip ZSTs
                     let mut caller_iter = caller_args.iter()
-                        .filter(|op| !skip_zst || !op.layout.is_zst())
+                        .filter(|op| !rust_abi || !op.layout.is_zst())
                         .map(|op| *op);
 
                     // Now we have to spread them out across the callee's locals,
@@ -359,11 +367,11 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
                             // Must be a tuple
                             for i in 0..dest.layout.fields.count() {
                                 let dest = self.place_field(dest, i as u64)?;
-                                self.pass_argument(skip_zst, &mut caller_iter, dest)?;
+                                self.pass_argument(rust_abi, &mut caller_iter, dest)?;
                             }
                         } else {
                             // Normal argument
-                            self.pass_argument(skip_zst, &mut caller_iter, dest)?;
+                            self.pass_argument(rust_abi, &mut caller_iter, dest)?;
                         }
                     }
                     // Now we should have no more caller args
@@ -374,7 +382,11 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
                     // Don't forget to check the return type!
                     if let Some(caller_ret) = dest {
                         let callee_ret = self.eval_place(&mir::Place::Local(mir::RETURN_PLACE))?;
-                        if !Self::check_argument_compat(caller_ret.layout, callee_ret.layout) {
+                        if !Self::check_argument_compat(
+                            rust_abi,
+                            caller_ret.layout,
+                            callee_ret.layout,
+                        ) {
                             return err!(FunctionRetMismatch(
                                 caller_ret.layout.ty, callee_ret.layout.ty
                             ));

src/librustc_mir/shim.rs

@@ -226,8 +226,13 @@ fn build_drop_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         // The first argument (index 0), but add 1 for the return value.
         let dropee_ptr = Place::Local(Local::new(1+0));
         if tcx.sess.opts.debugging_opts.mir_emit_retag {
-            // We use raw ptr operations, better prepare the alias tracking for that
+            // Function arguments should be retagged
             mir.basic_blocks_mut()[START_BLOCK].statements.insert(0, Statement {
+                source_info,
+                kind: StatementKind::Retag { fn_entry: true, place: dropee_ptr.clone() },
+            });
+            // We use raw ptr operations, better prepare the alias tracking for that
+            mir.basic_blocks_mut()[START_BLOCK].statements.insert(1, Statement {
                 source_info,
                 kind: StatementKind::EscapeToRaw(Operand::Copy(dropee_ptr.clone())),
             })

src/test/codegen-units/item-collection/drop_in_place_intrinsic.rs

@@ -14,7 +14,7 @@
 
 #![feature(start)]
 
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<drop_in_place_intrinsic::StructWithDtor[0]> @@ drop_in_place_intrinsic-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<drop_in_place_intrinsic::StructWithDtor[0]> @@ drop_in_place_intrinsic-cgu.0[Internal]
 struct StructWithDtor(u32);
 
 impl Drop for StructWithDtor {
@@ -26,7 +26,7 @@ impl Drop for StructWithDtor {
 #[start]
 fn start(_: isize, _: *const *const u8) -> isize {
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<[drop_in_place_intrinsic::StructWithDtor[0]; 2]> @@ drop_in_place_intrinsic-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<[drop_in_place_intrinsic::StructWithDtor[0]; 2]> @@ drop_in_place_intrinsic-cgu.0[Internal]
     let x = [StructWithDtor(0), StructWithDtor(1)];
 
     drop_slice_in_place(&x);
@@ -41,6 +41,7 @@ fn drop_slice_in_place(x: &[StructWithDtor]) {
         // not have drop-glue for the unsized [StructWithDtor]. This has to be
         // generated though when the drop_in_place() intrinsic is used.
         //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<[drop_in_place_intrinsic::StructWithDtor[0]]> @@ drop_in_place_intrinsic-cgu.0[Internal]
+        //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<[drop_in_place_intrinsic::StructWithDtor[0]]> @@ drop_in_place_intrinsic-cgu.0[Internal]
         ::std::ptr::drop_in_place(x as *const _ as *mut [StructWithDtor]);
     }
 }

src/test/codegen-units/item-collection/generic-drop-glue.rs

@@ -47,7 +47,7 @@ enum EnumNoDrop<T1, T2> {
 struct NonGenericNoDrop(i32);
 
 struct NonGenericWithDrop(i32);
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::NonGenericWithDrop[0]> @@ generic_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::NonGenericWithDrop[0]> @@ generic_drop_glue-cgu.0[Internal]
 
 impl Drop for NonGenericWithDrop {
     //~ MONO_ITEM fn generic_drop_glue::{{impl}}[2]::drop[0]
@@ -57,11 +57,11 @@ impl Drop for NonGenericWithDrop {
 //~ MONO_ITEM fn generic_drop_glue::start[0]
 #[start]
 fn start(_: isize, _: *const *const u8) -> isize {
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::StructWithDrop[0]<i8, char>> @@ generic_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::StructWithDrop[0]<i8, char>> @@ generic_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn generic_drop_glue::{{impl}}[0]::drop[0]<i8, char>
     let _ = StructWithDrop { x: 0i8, y: 'a' }.x;
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::StructWithDrop[0]<&str, generic_drop_glue::NonGenericNoDrop[0]>> @@ generic_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::StructWithDrop[0]<&str, generic_drop_glue::NonGenericNoDrop[0]>> @@ generic_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn generic_drop_glue::{{impl}}[0]::drop[0]<&str, generic_drop_glue::NonGenericNoDrop[0]>
     let _ = StructWithDrop { x: "&str", y: NonGenericNoDrop(0) }.y;
 
@@ -70,17 +70,17 @@ fn start(_: isize, _: *const *const u8) -> isize {
 
     // This is supposed to generate drop-glue because it contains a field that
     // needs to be dropped.
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::StructNoDrop[0]<generic_drop_glue::NonGenericWithDrop[0], f64>> @@ generic_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::StructNoDrop[0]<generic_drop_glue::NonGenericWithDrop[0], f64>> @@ generic_drop_glue-cgu.0[Internal]
     let _ = StructNoDrop { x: NonGenericWithDrop(0), y: 0f64 }.y;
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::EnumWithDrop[0]<i32, i64>> @@ generic_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::EnumWithDrop[0]<i32, i64>> @@ generic_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn generic_drop_glue::{{impl}}[1]::drop[0]<i32, i64>
     let _ = match EnumWithDrop::A::<i32, i64>(0) {
         EnumWithDrop::A(x) => x,
         EnumWithDrop::B(x) => x as i32
     };
 
-    //~MONO_ITEM fn core::ptr[0]::drop_in_place[0]<generic_drop_glue::EnumWithDrop[0]<f64, f32>> @@ generic_drop_glue-cgu.0[Internal]
+    //~MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<generic_drop_glue::EnumWithDrop[0]<f64, f32>> @@ generic_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn generic_drop_glue::{{impl}}[1]::drop[0]<f64, f32>
     let _ = match EnumWithDrop::B::<f64, f32>(1.0) {
         EnumWithDrop::A(x) => x,

src/test/codegen-units/item-collection/instantiation-through-vtable.rs

@@ -34,13 +34,13 @@ impl<T> Trait for Struct<T> {
 fn start(_: isize, _: *const *const u8) -> isize {
     let s1 = Struct { _a: 0u32 };
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<instantiation_through_vtable::Struct[0]<u32>> @@ instantiation_through_vtable-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<instantiation_through_vtable::Struct[0]<u32>> @@ instantiation_through_vtable-cgu.0[Internal]
     //~ MONO_ITEM fn instantiation_through_vtable::{{impl}}[0]::foo[0]<u32>
     //~ MONO_ITEM fn instantiation_through_vtable::{{impl}}[0]::bar[0]<u32>
     let _ = &s1 as &Trait;
 
     let s1 = Struct { _a: 0u64 };
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<instantiation_through_vtable::Struct[0]<u64>> @@ instantiation_through_vtable-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<instantiation_through_vtable::Struct[0]<u64>> @@ instantiation_through_vtable-cgu.0[Internal]
     //~ MONO_ITEM fn instantiation_through_vtable::{{impl}}[0]::foo[0]<u64>
     //~ MONO_ITEM fn instantiation_through_vtable::{{impl}}[0]::bar[0]<u64>
     let _ = &s1 as &Trait;

src/test/codegen-units/item-collection/non-generic-drop-glue.rs

@@ -15,7 +15,7 @@
 #![deny(dead_code)]
 #![feature(start)]
 
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<non_generic_drop_glue::StructWithDrop[0]> @@ non_generic_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<non_generic_drop_glue::StructWithDrop[0]> @@ non_generic_drop_glue-cgu.0[Internal]
 struct StructWithDrop {
     x: i32
 }
@@ -29,7 +29,7 @@ struct StructNoDrop {
     x: i32
 }
 
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<non_generic_drop_glue::EnumWithDrop[0]> @@ non_generic_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<non_generic_drop_glue::EnumWithDrop[0]> @@ non_generic_drop_glue-cgu.0[Internal]
 enum EnumWithDrop {
     A(i32)
 }

src/test/codegen-units/item-collection/transitive-drop-glue.rs

@@ -15,11 +15,11 @@
 #![deny(dead_code)]
 #![feature(start)]
 
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::Root[0]> @@ transitive_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::Root[0]> @@ transitive_drop_glue-cgu.0[Internal]
 struct Root(Intermediate);
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::Intermediate[0]> @@ transitive_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::Intermediate[0]> @@ transitive_drop_glue-cgu.0[Internal]
 struct Intermediate(Leaf);
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::Leaf[0]> @@ transitive_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::Leaf[0]> @@ transitive_drop_glue-cgu.0[Internal]
 struct Leaf;
 
 impl Drop for Leaf {
@@ -40,15 +40,15 @@ impl<T> Drop for LeafGen<T> {
 fn start(_: isize, _: *const *const u8) -> isize {
     let _ = Root(Intermediate(Leaf));
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::RootGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::IntermediateGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::LeafGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::RootGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::IntermediateGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::LeafGen[0]<u32>> @@ transitive_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn transitive_drop_glue::{{impl}}[1]::drop[0]<u32>
     let _ = RootGen(IntermediateGen(LeafGen(0u32)));
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::RootGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::IntermediateGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<transitive_drop_glue::LeafGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::RootGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::IntermediateGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<transitive_drop_glue::LeafGen[0]<i16>> @@ transitive_drop_glue-cgu.0[Internal]
     //~ MONO_ITEM fn transitive_drop_glue::{{impl}}[1]::drop[0]<i16>
     let _ = RootGen(IntermediateGen(LeafGen(0i16)));
 

src/test/codegen-units/item-collection/tuple-drop-glue.rs

@@ -15,7 +15,7 @@
 #![deny(dead_code)]
 #![feature(start)]
 
-//~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<tuple_drop_glue::Dropped[0]> @@ tuple_drop_glue-cgu.0[Internal]
+//~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<tuple_drop_glue::Dropped[0]> @@ tuple_drop_glue-cgu.0[Internal]
 struct Dropped;
 
 impl Drop for Dropped {
@@ -26,11 +26,11 @@ impl Drop for Dropped {
 //~ MONO_ITEM fn tuple_drop_glue::start[0]
 #[start]
 fn start(_: isize, _: *const *const u8) -> isize {
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<(u32, tuple_drop_glue::Dropped[0])> @@ tuple_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<(u32, tuple_drop_glue::Dropped[0])> @@ tuple_drop_glue-cgu.0[Internal]
     let x = (0u32, Dropped);
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<(i16, (tuple_drop_glue::Dropped[0], bool))> @@ tuple_drop_glue-cgu.0[Internal]
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<(tuple_drop_glue::Dropped[0], bool)> @@ tuple_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<(i16, (tuple_drop_glue::Dropped[0], bool))> @@ tuple_drop_glue-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<(tuple_drop_glue::Dropped[0], bool)> @@ tuple_drop_glue-cgu.0[Internal]
     let x = (0i16, (Dropped, true));
 
     0

src/test/codegen-units/item-collection/unsizing.rs

@@ -59,13 +59,13 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Wrapper<U>> for Wrapper<T>
 fn start(_: isize, _: *const *const u8) -> isize {
     // simple case
     let bool_sized = &true;
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<bool> @@ unsizing-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<bool> @@ unsizing-cgu.0[Internal]
     //~ MONO_ITEM fn unsizing::{{impl}}[0]::foo[0]
     let _bool_unsized = bool_sized as &Trait;
 
     let char_sized = &'a';
 
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<char> @@ unsizing-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<char> @@ unsizing-cgu.0[Internal]
     //~ MONO_ITEM fn unsizing::{{impl}}[1]::foo[0]
     let _char_unsized = char_sized as &Trait;
 
@@ -75,13 +75,13 @@ fn start(_: isize, _: *const *const u8) -> isize {
         _b: 2,
         _c: 3.0f64
     };
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<f64> @@ unsizing-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<f64> @@ unsizing-cgu.0[Internal]
     //~ MONO_ITEM fn unsizing::{{impl}}[2]::foo[0]
     let _struct_unsized = struct_sized as &Struct<Trait>;
 
     // custom coercion
     let wrapper_sized = Wrapper(&0u32);
-    //~ MONO_ITEM fn core::ptr[0]::drop_in_place[0]<u32> @@ unsizing-cgu.0[Internal]
+    //~ MONO_ITEM fn core::ptr[0]::real_drop_in_place[0]<u32> @@ unsizing-cgu.0[Internal]
     //~ MONO_ITEM fn unsizing::{{impl}}[3]::foo[0]
     let _wrapper_sized = wrapper_sized as Wrapper<Trait>;