Function payload_from_raw 

pub unsafe fn payload_from_raw<'a>(
    kind: EventKind,
    payload_ptr: *const c_void,
) -> EventPayload<'a>

Helper: convert a raw (kind, payload_ptr) pair into a typed EventPayload borrow. Used inside EventCallback trampolines.

Safety

Caller guarantees payload_ptr matches the variant indicated by kind and is valid for the borrow lifetime.