#![feature(core_intrinsics, rustc_attrs)] use std::intrinsics::rustc_peek; #[rustc_mir(rustc_peek_liveness, stop_after_dataflow)] fn foo() { { let mut x: (i32, i32) = (42, 0); // Assignment to a projection does not cause `x` to become live unsafe { rustc_peek(x); } //~ ERROR bit not set x.1 = 42; x = (0, 42); // ...but a read from a projection does. unsafe { rustc_peek(x); } println!("{}", x.1); } { let mut x = 42; // Derefs are treated like a read of a local even if they are on the LHS of an assignment. let p = &mut x; unsafe { rustc_peek(&p); } *p = 24; unsafe { rustc_peek(&p); } //~ ERROR bit not set } } fn main() {}