message: This is unreachable code and it should never ever be reachable even in the future
diff: @@ -254,7 +254,7 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
  }
  Aggregate(..) |
  - Variant(_) => unimplemented!(),
  + Variant(_) => bug!("should not have aggregate or variant constants in MIR"),
  // function items are zero sized and thus have no readable value
  Function(..) => PrimVal::Undef,
  };
  