Add negative impls for *const T and *mut T

src/libcore/lib.rs

@@ -68,6 +68,7 @@
 #![feature(staged_api)]
 #![feature(unboxed_closures)]
 #![feature(rustc_attrs)]
+#![feature(optin_builtin_traits)]
 
 #[macro_use]
 mod macros;

src/libcore/marker.rs

@@ -49,6 +49,9 @@ pub unsafe trait Send : MarkerTrait {
     // empty.
 }
 
+impl<T> !Send for *const T { }
+impl<T> !Send for *mut T { }
+
 /// Types with a constant size known at compile-time.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[lang="sized"]
@@ -214,6 +217,9 @@ pub unsafe trait Sync : MarkerTrait {
     // Empty
 }
 
+impl<T> !Sync for *const T { }
+impl<T> !Sync for *mut T { }
+
 /// A type which is considered "not POD", meaning that it is not
 /// implicitly copyable. This is typically embedded in other types to
 /// ensure that they are never copied, even if they lack a destructor.

src/librustc/middle/traits/select.rs

@@ -1377,8 +1377,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
                     ty::BoundSync |
                     ty::BoundSend => {
-                        // sync and send are not implemented for *const, *mut
+                        self.tcx().sess.bug(
-                        Err(Unimplemented)
+                            &format!(
+                                "raw pointers should have a negative \
+                                 impl for `Send` and `Sync`")[]);
                     }
                 }
             }