Register generic argument use at startup

[andriyDev]

I don't really know how to go about this, so I've come here (since I figure you all might have more understanding). Essentially what I want is to create a factory of every type that a function is called for (essentially every monomorphization).

The following is roughly my code:

fn do_something_with<T>(t: T) {
  #[ctor::ctor]
  fn register() {
    register_factory::<T>();
  }

  // Do something with t
  ...
}

fn register_factory<T>() {
  // Put T in a HashMap after making a factory type.
  ...
}

Unfortunately, I can't do this because the register function can't refer to T, due to rustc --explain E0401 (inner fns do not inherit type or const parameters from functions they are embedded in).

I'm not sure if this is even possible, or maybe there's a way to extend ctor to allow calling generic functions?