Macro rusticata_macros::upgrade_error_to

macro_rules! upgrade_error_to {
    ($i : expr, $ty : ty, $submac : ident! ($($args : tt) *)) => { ... };
    ($i : expr, $ty : ty, $f : expr) => { ... };
    ($ty : ty, $e : expr) => { ... };
}

Apply combinator, trying to “upgrade” error to next error type (using the Into or From traits).