Describe the bug
Doing something like:

if constexpr(std::constructible_from<tf::cudaGraph_t, std::string>) {
  return tf::cudaGraph_t("hello");
else {
  return tf::cudaGrapg_t();
}

cause a compilation error as the constructor in tf::cudaGrapg_t just delegates to it's creator. Adding a simple requires(std::invocable<Creator, Args...>) to the constructor would probably solve the issue.