ptr::read docs are bogus

[kmcallister]

Reads the value from src without dropping it.

But in fact this code does run the destructor:

use std::{ptr, mem};

struct Foo;

impl Drop for Foo {
    fn drop(&mut self) {
        println!("drop day");
    }
} 

fn main() {
    let x = Foo;
    unsafe {
        ptr::read(&x as *const Foo);
        mem::forget(x);
    }
} 

It's not clear what "without dropping it" means. I suspect the point is that it won't mark the target (hence *const T) as destroyed, from an era when this was more of a dynamic notion than today. But at any rate, the docs should reflect reality. As far as I know this is the way to explicitly run a destructor in Rust — a nice duality because ptr::write is the "placement new" for uninitialized memory.

[kmcallister]

cc @steveklabnik

[Gankra]

I actually recently wrote this 😓

I think maybe this should instead say "without moving it"?