// This tests that the size of Option<Box<i32>> is the same as *const i32. fn option_box_deref() -> i32 { let val = Some(Box::new(42)); unsafe { let ptr: *const i32 = std::mem::transmute::<Option<Box<i32>>, *const i32>(val); let ret = *ptr; // unleak memory std::mem::transmute::<*const i32, Option<Box<i32>>>(ptr); ret } } fn main() { assert_eq!(option_box_deref(), 42); }