portable static asserts

Author: lemire

include/roaring/portability.h

@@ -587,6 +587,13 @@ static inline uint32_t croaring_refcount_get(const croaring_refcount_t *val) {
     { 0 }
 #endif
 
+#if defined(__cplusplus)
+#define CROARING_STATIC_ASSERT(x,y) static_assert(x, y)
+#else
+#define CROARING_STATIC_ASSERT(x,y) _Static_assert(x, y)
+#endif
+
+
 // We need portability.h to be included first,
 // but we also always want isadetection.h to be
 // included (right after).

src/art/art.c

@@ -2284,13 +2284,13 @@ bool art_internal_validate(const art_t *art, const char **reason,
     return art_internal_validate_at(art, art->root, validator);
 }
 
-_Static_assert(alignof(art_leaf_t) == alignof(art_node4_t),
+CROARING_STATIC_ASSERT(alignof(art_leaf_t) == alignof(art_node4_t),
                "Serialization assumes node type alignment is equal");
-_Static_assert(alignof(art_leaf_t) == alignof(art_node16_t),
+CROARING_STATIC_ASSERT(alignof(art_leaf_t) == alignof(art_node16_t),
                "Serialization assumes node type alignment is equal");
-_Static_assert(alignof(art_leaf_t) == alignof(art_node48_t),
+CROARING_STATIC_ASSERT(alignof(art_leaf_t) == alignof(art_node48_t),
                "Serialization assumes node type alignment is equal");
-_Static_assert(alignof(art_leaf_t) == alignof(art_node256_t),
+CROARING_STATIC_ASSERT(alignof(art_leaf_t) == alignof(art_node256_t),
                "Serialization assumes node type alignment is equal");
 
 size_t art_size_in_bytes(const art_t *art) {
@@ -2363,7 +2363,7 @@ size_t art_frozen_view(const char *buf, size_t maxbytes, art_t *art) {
     if (maxbytes < sizeof(art->capacities)) {
         return 0;
     }
-    _Static_assert(sizeof(art->first_free) == sizeof(art->capacities),
+    CROARING_STATIC_ASSERT(sizeof(art->first_free) == sizeof(art->capacities),
                    "first_free is read from capacities");
     memcpy(art->first_free, buf, sizeof(art->capacities));
     memcpy(art->capacities, buf, sizeof(art->capacities));