How can you make a safe static singleton in Rust?

Question

This is something of a controversial topic, so let me start by explaining my use case, and then talk about the actual problem.

I find that for a bunch of unsafe thin

Answer 1

It looks like a use case for std::sync::Once:

use std::sync::{Once, ONCE_INIT};
static INIT: Once = ONCE_INIT;

Then in your tests call

INIT.doit(|| unsafe { init(); });

Once guarantees that your init will only be executed once, no matter how many times you call INIT.doit().