cryptodev: fix clang C++ include

When compiling on FreeBSD with clang and include checking enabled,
errors are emitted due to differences in how empty structs/unions are
handled in C and C++, as C++ structs cannot have zero size.

lib/cryptodev/rte_crypto.h:127:2: error:
union has size 0 in C, non-zero size in C++

Since the contents of the union are all themselves of zero size,
the actual union wrapper is unnecessary. We therefore remove it for C++
builds - though keep it for C builds for safety and clarity of
understanding the code.

Fixes: c0f87eb5252b ("cryptodev: change burst API to be crypto op oriented")
Fixes: d2a4223c4c6d ("cryptodev: do not store pointer to op specific params")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

diff --git a/lib/cryptodev/rte_crypto.h b/lib/cryptodev/rte_crypto.h
index a864f5036f3a6d7da35fd405ef5ebcbc66925f7e..aeb3bf6e383ac03a291d21a372e1fc77cff6aaed 100644 (file)
--- a/lib/cryptodev/rte_crypto.h
+++ b/lib/cryptodev/rte_crypto.h
@@ -123,15 +123,24 @@ struct rte_crypto_op {
        rte_iova_t phys_addr;
        /**< physical address of crypto operation */
 
+/* empty structures do not have zero size in C++ leading to compilation errors
+ * with clang about structure/union having different sizes in C and C++.
+ * While things are clearer with an explicit union, since each field is
+ * zero-sized it's not actually needed, so omit it for C++
+ */
+#ifndef __cplusplus
        __extension__
        union {
+#endif
                struct rte_crypto_sym_op sym[0];
                /**< Symmetric operation parameters */
 
                struct rte_crypto_asym_op asym[0];
                /**< Asymmetric operation parameters */
 
+#ifndef __cplusplus
        }; /**< operation specific parameters */
+#endif
 };
 
 /**