Is assignment to an uninit but non-Drop place okay?

[ChayimFriedman2]

I don't see an issue about this (although #307) is close, and I'm pretty sure this is undecided.

Can we use assignment (and not ptr::write()) to write to an uninitialized place of a type that does not have a drop glue? That is, this:

fn main() {
    let mut v = std::mem::MaybeUninit::<i32>::uninit();
    unsafe {
        *v.as_mut_ptr() = 123;
    }
}

Miri does not flag this.

[RalfJung]

Seems fairly clear to me that this is fine. How could this code plausibly have UB?

[ChayimFriedman2]

If we say that dropping a value always touches it, even if it does not has a drop glue.