// General test of maybe_uninits state computed by MIR dataflow. #![feature(core_intrinsics, rustc_attrs)] use std::intrinsics::rustc_peek; use std::mem::{drop, replace}; struct S(i32); #[rustc_mir(rustc_peek_maybe_uninit,stop_after_dataflow)] fn foo(x: &mut S) { // `x` is initialized here, so maybe-uninit bit is 0. unsafe { rustc_peek(&x) }; //~ ERROR rustc_peek: bit not set ::std::mem::drop(x); // `x` definitely uninitialized here, so maybe-uninit bit is 1. unsafe { rustc_peek(&x) }; } fn main() { foo(&mut S(13)); foo(&mut S(13)); }