‘iv‘ specifies undefined struct/union ‘evp_cipher_ctx_st‘

struct evp_cipher_ctx_st {
    const EVP_CIPHER *cipher;
    ENGINE *engine;             /* functional reference if 'cipher' is
                                 * ENGINE-provided */
    int encrypt;                /* encrypt or decrypt */
    int buf_len;                /* number we have left */
    unsigned char oiv[EVP_MAX_IV_LENGTH]; /* original iv */
    unsigned char iv[EVP_MAX_IV_LENGTH]; /* working iv */
    unsigned char buf[EVP_MAX_BLOCK_LENGTH]; /* saved partial block */
    int num;                    /* used by cfb/ofb/ctr mode */
    /* FIXME: Should this even exist? It appears unused */
    void *app_data;             /* application stuff */
    int key_len;                /* May change for variable length cipher */
    unsigned long flags;        /* Various flags */
    void *cipher_data;          /* per EVP data */
    int final_used;
    int block_mask;
    unsigned char final[EVP_MAX_BLOCK_LENGTH]; /* possible final block */
} /* EVP_CIPHER_CTX */ ;

crypto/evp/evp_local.h