Function secp256k1_sys::secp256k1_xonly_pubkey_from_pubkey

pub unsafe extern "C" fn secp256k1_xonly_pubkey_from_pubkey(
    cx: *const Context,
    xonly_pubkey: *mut XOnlyPublicKey,
    pk_parity: *mut c_int,
    pubkey: *const PublicKey
) -> c_int

Available on non-secp256k1_fuzz only.