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// run-pass
use std::mem;
pub fn main() {
// By Ref Capture
let a = 10i32;
let b = Some(|| println!("{}", a));
// When we capture by reference we can use any of the
// captures as the discriminant since they're all
// behind a pointer.
assert_eq!(mem::size_of_val(&b), mem::size_of::<usize>());
// By Value Capture
let a = Box::new(12i32);
let b = Some(move || println!("{}", a));
// We captured `a` by value and since it's a `Box` we can use it
// as the discriminant.
assert_eq!(mem::size_of_val(&b), mem::size_of::<Box<i32>>());
// By Value Capture - Transitive case
let a = "Hello".to_string(); // String -> Vec -> Unique -> NonZero
let b = Some(move || println!("{}", a));
// We captured `a` by value and since down the chain it contains
// a `NonZero` field, we can use it as the discriminant.
assert_eq!(mem::size_of_val(&b), mem::size_of::<String>());
// By Value - No Optimization
let a = 14i32;
let b = Some(move || println!("{}", a));
// We captured `a` by value but we can't use it as the discriminant
// thus we end up with an extra field for the discriminant
assert_eq!(mem::size_of_val(&b), mem::size_of::<(i32, i32)>());
}
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