It's easy to demonstrate that destructors run after evaluating `return` in Rust:

    struct PrintOnDrop;
    
    impl Drop for PrintOnDrop {
        fn drop(&mut self) {
            println!("dropped");
        }
    }
    
    fn main() {
        let p = PrintOnDrop;
        return println!("returning");
    }

But the idea of altering the return value of a function from within a `defer` block after a `return` is evaluated is zany. Please never do that, in any language.