Match Ergonomics Issue B: Lifetime semantics change

main.rs

macro_rules! fn_handler {
    () => {

        struct Final<'a> {
            _ptr_a: *const i32,
            _ptr_b: *const i32,
            _marker: ::std::marker::PhantomData<&'a ()>,
        }

        fn handle<'a, 'b>(data: &Data<'a, 'b>) -> Final<'a> {
            let (a, b) = get(data);
            Final {
                _ptr_a: a as *const _,
                _ptr_b: b as *const _,
                _marker: ::std::marker::PhantomData,
            }
        }
    }
}

mod single {

    struct Data<'a, 'b> {
        first: &'a (i32, i32),
        _second: &'b i32,
    }

    pub fn run() {
        handle(&Data {
            first: &(23, 42),
            _second: &93,
        });
    }

    fn get<'a, 'b>(data: &Data<'a, 'b>) -> &'a (i32, i32) { data.first }

    fn_handler!();
}

mod multiple {

    struct Data<'a, 'b> {
        first_a: &'a i32,
        first_b: &'b i32,
        _second: &'b i32,
    }

    fn get<'a, 'b>(data: &Data<'a, 'b>) -> (&'a i32, &'b i32) { (data.first_a, data.first_b) }
    
    pub fn run() {
        handle(&Data {
            first_a: &23,
            first_b: &42,
            _second: &93,
        });
    }

    fn_handler!();
}

fn main() {
    single::run();
    multiple::run();
}