lib: use C99 syntax for zero-size arrays

Exported header files used by applications should allow the strictest
compiler flags. Language extensions used in many places must be explicitly
marked or removed to avoid warnings and compilation failures.

The extension keyword is used whenever the C99 syntax cannot do it.

This commit prevents the following errors:

 error: ISO C forbids zero-size array `[...]'

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

lib/librte_acl/rte_acl.h

@@ -144,7 +144,7 @@ struct rte_acl_rule_data {
 	struct rte_acl_field field[fld_num];         \
 }
 
-RTE_ACL_RULE_DEF(rte_acl_rule, 0);
+RTE_ACL_RULE_DEF(rte_acl_rule,);
 
 #define	RTE_ACL_RULE_SZ(fld_num)	\
 	(sizeof(struct rte_acl_rule) + sizeof(struct rte_acl_field) * (fld_num))

lib/librte_cryptodev/rte_cryptodev.h

@@ -759,7 +759,7 @@ struct rte_cryptodev_sym_session {
 	} __rte_aligned(8);
 	/**< Public symmetric session details */
 
-	char _private[0];
+	char _private[];
 	/**< Private session material */
 };
 

lib/librte_cryptodev/rte_cryptodev_pmd.h

@@ -71,7 +71,7 @@ struct rte_cryptodev_session {
 		struct rte_mempool *mp;
 	} __rte_aligned(8);
 
-	char _private[0];
+	__extension__ char _private[0];
 };
 
 struct rte_cryptodev_driver;

lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h

@@ -102,7 +102,7 @@ struct rte_kni_fifo {
 	volatile unsigned read;      /**< Next position to be read */
 	unsigned len;                /**< Circular buffer length */
 	unsigned elem_size;          /**< Pointer size - for 32/64 bit OS */
-	void * volatile buffer[0];   /**< The buffer contains mbuf pointers */
+	void *volatile buffer[];     /**< The buffer contains mbuf pointers */
 };
 
 /*

lib/librte_hash/rte_fbk_hash.h

@@ -115,7 +115,7 @@ struct rte_fbk_hash_table {
 	uint32_t init_val;		/**< For initialising hash function. */
 
 	/** A flat table of all buckets. */
-	union rte_fbk_hash_entry t[0];
+	union rte_fbk_hash_entry t[];
 };
 
 /**

lib/librte_ip_frag/rte_ip_frag.h

@@ -124,7 +124,7 @@ struct rte_ip_frag_tbl {
 	struct ip_frag_pkt *last;         /**< last used entry. */
 	struct ip_pkt_list lru;           /**< LRU list for table entries. */
 	struct ip_frag_tbl_stat stat;     /**< statistics counters. */
-	struct ip_frag_pkt pkt[0];        /**< hash table. */
+	struct ip_frag_pkt pkt[];         /**< hash table. */
 };
 
 /** IPv6 fragment extension header */

lib/librte_lpm/rte_lpm.h

@@ -193,7 +193,7 @@ struct rte_lpm_v20 {
 			__rte_cache_aligned; /**< LPM tbl24 table. */
 	struct rte_lpm_tbl_entry_v20 tbl8[RTE_LPM_TBL8_NUM_ENTRIES]
 			__rte_cache_aligned; /**< LPM tbl8 table. */
-	struct rte_lpm_rule_v20 rules_tbl[0] \
+	struct rte_lpm_rule_v20 rules_tbl[]
 			__rte_cache_aligned; /**< LPM rules. */
 };
 

lib/librte_mbuf/rte_mbuf.h

@@ -756,8 +756,11 @@ const char *rte_get_tx_ol_flag_name(uint64_t mask);
 
 /* define a set of marker types that can be used to refer to set points in the
  * mbuf */
+__extension__
 typedef void    *MARKER[0];   /**< generic marker for a point in a structure */
+__extension__
 typedef uint8_t  MARKER8[0];  /**< generic marker with 1B alignment */
+__extension__
 typedef uint64_t MARKER64[0]; /**< marker that allows us to overwrite 8 bytes
                                * with a single assignment */
 

lib/librte_pipeline/rte_pipeline.h

@@ -252,7 +252,7 @@ struct rte_pipeline_table_entry {
 		uint32_t table_id;
 	};
 	/** Start of table entry area for user defined actions and meta-data */
-	uint8_t action_data[0];
+	__extension__ uint8_t action_data[0];
 };
 
 /**

lib/librte_ring/rte_ring.h

@@ -187,7 +187,7 @@ struct rte_ring {
 	struct rte_ring_debug_stats stats[RTE_MAX_LCORE];
 #endif
 
-	void * ring[0] __rte_cache_aligned; /**< Memory space of ring starts here.
+	void *ring[] __rte_cache_aligned;   /**< Memory space of ring starts here.
 	                                     * not volatile so need to be careful
 	                                     * about compiler re-ordering */
 };

lib/librte_sched/rte_bitmap.h

@@ -103,7 +103,7 @@ struct rte_bitmap {
 	uint32_t go2;     /**< Bitmap scan: Go/stop condition for current array2 cache line */
 
 	/* Storage space for array1 and array2 */
-	uint8_t memory[0];
+	uint8_t memory[];
 };
 
 static inline void