#![feature(custom_mir, core_intrinsics)] use std::intrinsics::mir::*; #[repr(packed)] struct S { field: [u32; 2], } #[custom_mir(dialect = "runtime", phase = "optimized")] fn test() { mir! { let s: S; { // Store a repeat expression directly into a field of a packed struct. s.field = [0; 2]; Return() } } } fn main() { // Run this a bunch of time to make sure it doesn't pass by chance. for _ in 0..20 { test(); } }