Function abi_stable::prefix_type::panic_on_missing_fieldname

pub fn panic_on_missing_fieldname<T, FieldTy>(
    fieldname: &&'static str, 
    actual_layout: &'static PTStructLayout
) -> ! where
    T: PrefixTypeTrait, 

Used to panic with an error message informing the user that a field is expected to be on the T type when it's not.