DebugValue

A Wrapper type for values that are only needed with debug assertions.

lib.rs:

A DebugValue<T> is a T that is only present if debug assertions are enabled. On debug builds it has the exact same layout as T. On release builds it is a zero-sized-type.

let mut x = String::from("Mutated but restored by f");
let passed_in = DebugValue::new_cloned(&x);
f(&mut x);
passed_in.assert_eq(&x);