How can I transmute a `MaybeUninit<T>` to a `T`?

I’d like to transmute a MaybeUninit<T> to a T.

use std::mem::transmute;
use std::mem::MaybeUninit;

fn make_init<T: Sized>(mt: MaybeUninit<T>) -> T {
    unsafe { transmute(mt) }
}

fn main() {
    make_init(MaybeUninit::new(1));
}

However this program gives me:

error[E0512]: cannot transmute between types of different sizes, or dependently-sized types

What’s the right way to do this?

>Solution :

Generally, the workaround when the compiler doesn’t know that types have the same size is to use transmute_copy(), but in your case there is MaybeUninit::assume_init() that does exactly what you want.