Function secp256k1_sys::secp256k1_ec_pubkey_serialize

pub unsafe extern "C" fn secp256k1_ec_pubkey_serialize(
    cx: *const Context,
    output: *mut c_uchar,
    out_len: *mut size_t,
    pk: *const PublicKey,
    compressed: c_uint
) -> c_int

Available on non-secp256k1_fuzz only.