mem::transmute to nevertype causes Illigal instruction

[DutchGhost]

transmuting to the never type causes an Illigal instruction: https://play.rust-lang.org/?gist=390b8739cfe0e25504f0602dcf546e7b&version=nightly&mode=release

#![feature(never_type)]

use std::mem;

fn main() {
    let _: ! = unsafe { mem::transmute( {} ) };
}

Now, it's true that this requires unsafe, and might not even considered an issue or bug, and probably never happens in real productions code. However, many transmutes give a segfault when done wrong, this instead gives an illigal instruction.

[jonas-schievink]

This is just UB, the code can do whatever. It's only an illegal instruction (ud2) because the compiler is nice. I think LLVM's trap-unreachable flag is doing this - otherwise main would just contain no instructions (since ! cannot be created main can never be reached) and fall through to whatever code happens to follow it.

[cuviper]

This is very similar to #50976.

[sfackler]

Closing as a duplicate of #50976.