Retag argument to drop_in_place unconditionally

compiler/rustc_mir_transform/src/shim.rs

@@ -174,7 +174,6 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
     let mut body =
         new_body(source, blocks, local_decls_for_sig(&sig, span), sig.inputs().len(), span);
 
-    if ty.is_some() {
     // The first argument (index 0), but add 1 for the return value.
     let mut dropee_ptr = Place::from(Local::new(1 + 0));
     if tcx.sess.opts.unstable_opts.mir_emit_retag {
@@ -203,6 +202,8 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
                 .push(Statement { source_info, kind: s });
         }
     }
+
+    if ty.is_some() {
         let patch = {
             let param_env = tcx.param_env_reveal_all_normalized(def_id);
             let mut elaborator =

src/tools/miri/tests/fail/stacked_borrows/drop_in_place_protector.rs

@@ -10,7 +10,7 @@ impl Drop for HasDrop {
     fn drop(&mut self) {
         unsafe {
             let _val = *P;
-            //~^ ERROR: /not granting access .* because that would remove .* which is protected/
+            //~^ ERROR: /not granting access .* because that would remove .* which is strongly protected/
         }
     }
 }

src/tools/miri/tests/fail/stacked_borrows/drop_in_place_protector.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is protected because it is an argument of call ID
+error: Undefined Behavior: not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is strongly protected because it is an argument of call ID
   --> $DIR/drop_in_place_protector.rs:LL:CC
    |
 LL |             let _val = *P;
-   |                        ^^ not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is protected because it is an argument of call ID
+   |                        ^^ not granting access to tag <TAG> because that would remove [Unique for <TAG>] which is strongly protected because it is an argument of call ID
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
    = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information

src/tools/miri/tests/fail/stacked_borrows/drop_in_place_retag.rs

@@ -3,16 +3,9 @@
 
 //@error-pattern: /retag .* for Unique permission .* only grants SharedReadOnly permission/
 
-#[repr(transparent)]
-struct HasDrop;
-
-impl Drop for HasDrop {
-    fn drop(&mut self) {}
-}
-
 fn main() {
     unsafe {
-        let x = (0u8, HasDrop);
+        let x = 0u8;
         let x = core::ptr::addr_of!(x);
         core::ptr::drop_in_place(x.cast_mut());
     }

src/tools/miri/tests/fail/stacked_borrows/drop_in_place_retag.stderr

@@ -15,7 +15,7 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x0..0x1]
 LL |         let x = core::ptr::addr_of!(x);
    |                 ^^^^^^^^^^^^^^^^^^^^^^
    = note: BACKTRACE:
-   = note: inside `std::ptr::drop_in_place::<(u8, HasDrop)> - shim(Some((u8, HasDrop)))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
+   = note: inside `std::ptr::drop_in_place::<u8> - shim(None)` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
 note: inside `main` at $DIR/drop_in_place_retag.rs:LL:CC
   --> $DIR/drop_in_place_retag.rs:LL:CC
    |

src/tools/miri/tests/pass/drop_in_place_null.rs

@@ -1,7 +0,0 @@
-// Make sure that dropping types with no drop glue is DB even for invalid pointers.
-
-fn main() {
-    unsafe {
-        core::ptr::drop_in_place::<u8>(core::ptr::null_mut());
-    }
-}