Use proper intrinsic type

src/libcore/intrinsics.rs

@@ -1352,12 +1352,7 @@ extern "rust-intrinsic" {
     /// Internal hook used by Miri to implement unwinding.
     /// Perma-unstable: do not use
     #[cfg(not(bootstrap))]
-    // Note that the type is data is pretty arbitrary:
-    // we just need something that's guarnateed to be a fat
-    // pointer. Using `*mut [()]` instead of the actual type
-    // `*mut (Any + Send)` allows us to avoid making `Any` and `Send`
-    // lang items
-    pub fn miri_start_panic(data: *mut [()]) -> !;
+    pub fn miri_start_panic(data: *mut (dyn crate::any::Any + crate::marker::Send)) -> !;
 }
 
 // Some functions are defined here because they accidentally got made

src/libpanic_unwind/miri.rs

@@ -6,8 +6,7 @@ pub fn payload() -> *mut u8 {
 }
 
 pub unsafe fn panic(data: Box<dyn Any + Send>) -> ! {
-    let raw_val: *mut [()] = core::mem::transmute::<*mut (dyn Any + Send), _>(Box::into_raw(data));
-    core::intrinsics::miri_start_panic(raw_val)
+    core::intrinsics::miri_start_panic(Box::into_raw(data))
 }
 
 pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {

src/librustc_typeck/check/intrinsic.rs

@@ -385,7 +385,9 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem) {
             }
 
             "miri_start_panic" => {
-                (0, vec![tcx.mk_mut_ptr(tcx.mk_slice(tcx.mk_unit()))], tcx.types.never)
+                // TODO - the relevant types aren't lang items,
+                // so it's not trivial to check this
+                return;
             }
 
             ref other => {