macro_rules! expand_type_bound {
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal, $($rest:tt)*) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:ty, $($rest:tt)*) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:ty) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal <: $ub:ty, $($rest:tt)*) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal <: $ub:ty) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal >: $lb:ty, $($rest:tt)*) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal >: $lb:ty) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal <: $ub:ty >: $lb:ty, $($rest:tt)*) => { ... };
    ($nth:expr, $frame:expr, $svec_ref:expr, $t:literal <: $ub:ty >: $lb:ty) => { ... };
}