message: Rvalue::Box -> Rvalue::NullaryOp
diff: @@ -788,11 +788,15 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
  self.write_value(val, dest, dest_ty)?;
  }
  - Box(ty) => {
  + NullaryOp(mir::NullOp::Box, ty) => {
  let ptr = self.alloc_ptr(ty)?;
  self.write_primval(dest, PrimVal::Ptr(ptr), dest_ty)?;
  }
  + NullaryOp(mir::NullOp::SizeOf, _ty) => {
  + unimplemented!()
  + }
  +
  Cast(kind, ref operand, cast_ty) => {
  debug_assert_eq!(self.monomorphize(cast_ty, self.substs()), dest_ty);
  use rustc::mir::CastKind::*;
  