Align the associated error types of multiple traits (when you know they're actually the same type)

align_multiple_traits_associated_error.rs

trait T {
    type TErr;
}

trait U {
    type UErr;
}

#[derive(Debug)]
struct S;

impl T for S {
    type TErr = &'static str;
}

impl U for S {
    type UErr = &'static str;
}

fn setup() -> (
    impl T<TErr = &'static str> + U<UErr = &'static str> + std::fmt::Debug,
    u32,
) {
    (S, 5)
}

fn main() {
    let (s, _) = setup();
    dbg!(s);
}