What is `~` used for?

I found ~ being used in option.rs:779. I came across some old rust code using ~ for pointers, but I never saw it being used this way. This is not from some old version of rust core lib, it's current version.

Here is code example from source code:

pub const fn unwrap_or(self, default: T) -> T
    where
        T: ~const Drop + ~const Destruct,
    {
        match self {
            Some(x) => x,
            None => default,
        }
    }