Macro lang_extension::raw_type_converter

macro_rules! raw_type_converter {
    (inner $type: ty, $source_type: ty, $target_type: ty) => { ... };
    ($type: ty, $source_type: ty, $target_type: ty) => { ... };
    ($generic_type: tt; $source_type: tt; $target_type: tt) => { ... };
}