Idea for hashing pointers to unsized types

[durka]

Can this trick (essentially, compare sizeof &T::Target to sizeof usize) be used to eliminate the FIXME?

by_address/src/lib.rs

Lines 134 to 138 in 3bdda92

	fn hash<H: Hasher>(&self, state: &mut H) {
	// FIXME: For fat pointers to dynamically-sized types, this discards the extra data (vtable
	// pointer or length), so it may have a high collision rate in certain cases.
	(self.addr() as *const ()).hash(state)
	}

[mbrubeck]

Yes, and I just landed that in libstd: rust-lang/rust#45483.

I'm wary about using it in this crate, since it depends on assumptions about the (implementation-defined) layout of pointers to unsized types. My current plan is to wait until the implementation in libstd is stable, and then depend on that.