message: Return `[size]` shape if size is known for Bincount.
diff: @@ -1420,8 +1420,20 @@ REGISTER_OP("Bincount")
  // The input `size` must be a scalar.
  TF_RETURN_IF_ERROR(c->WithRank(c->input(1), 0, &unused));
  + const Tensor* size_tensor = c->input_tensor(1);
  + if (size_tensor == nullptr) {
  + // Return unknown shape if size is not known.
  c->set_output(0, c->UnknownShapeOfRank(1));
  return Status::OK();
  + }
  +
  + // Return `[size]` shape if size is known.
  + int32 size_val = size_tensor->scalar<int32>()();
  + if (size_val < 0) {
  + return errors::InvalidArgument("size (", size_val, ") must be non-negative");
  + }
  + c->set_output(0, c->MakeShape({size_val}));
  + return Status::OK();
  });
  REGISTER_OP("Cumsum")
  