This made me think about what you could potentially do to get a similar sort of thing using the type system instead of the built-in effect of unsafe.

Seems like you could create a sort of userland-unsafe by using a closed trait[1] and requiring its use on a 'dangerous' method or struct or whatever:

   mod my_unsafe {
      pub trait MyUnsafe {}
   }
   pub struct MyUnsafe;
   impl my_unsafe::MyUnsafe for MyUnsafe;

   pub fn dangerous_function<U: my_unsafe::MyUnsafe>() {}

   fn main() {
     dangerous_function::<MyUnsafe>()
   }

Obviously this doesn't let you do a block of unsafe without having to repeat it like `unsafe {}` does, but it doesn't leave you much room to do the dangerous things without the shrinkwrap agreement either (and turbofish are so ugly at least for me they'd be a deterrent).

That said I find the named use-case kind of weird. The whole point of the library is to do these unsafe things, so it's kind of silly to be like "don't forget it's dangerous!"