Function module_speak_sync 

pub unsafe extern "C" fn module_speak_sync(
    data: *const c_char,
    len: usize,
    msgtype: MessageType,
) -> c_int

Synchonous speak

Your module implementation must export it’s own version of either module_speak or function as:

#[unsafe(no_mangle)]
unsafe extern "C" fn module_speak_sync(data: *const raw::c_char, len: usize, msgtype: MessageType) -> raw::c_int {
    // Implementation
}