Preserve output of raw pointers in mir dump.

src/librustc/mir/mod.rs

@@ -2602,9 +2602,16 @@ impl<'tcx> Debug for Constant<'tcx> {
 impl<'tcx> Display for Constant<'tcx> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         write!(fmt, "const ")?;
+        // FIXME make the default pretty printing of raw pointers more detailed. Here we output the
+        // debug representation of raw pointers, so that the raw pointers in the mir dump output are
+        // detailed and just not '{pointer}'.
+        if let ty::RawPtr(_) = self.literal.ty.kind {
+            write!(fmt, "{:?} : {}", self.literal.val, self.literal.ty)
+        } else {
             write!(fmt, "{}", self.literal)
         }
     }
+}
 
 impl<'tcx> graph::DirectedGraph for Body<'tcx> {
     type Node = BasicBlock;