prevector: Avoid unnamed struct, which is a GNU extension

src/prevector.h

@@ -152,7 +152,7 @@ private:
         struct {
             char* indirect;
             size_type capacity;
-        };
+        } indirect_contents;
     };
 #pragma pack(pop)
     alignas(char*) direct_or_indirect _union = {};
@@ -163,8 +163,8 @@ private:
 
     T* direct_ptr(difference_type pos) { return reinterpret_cast<T*>(_union.direct) + pos; }
     const T* direct_ptr(difference_type pos) const { return reinterpret_cast<const T*>(_union.direct) + pos; }
-    T* indirect_ptr(difference_type pos) { return reinterpret_cast<T*>(_union.indirect) + pos; }
-    const T* indirect_ptr(difference_type pos) const { return reinterpret_cast<const T*>(_union.indirect) + pos; }
+    T* indirect_ptr(difference_type pos) { return reinterpret_cast<T*>(_union.indirect_contents.indirect) + pos; }
+    const T* indirect_ptr(difference_type pos) const { return reinterpret_cast<const T*>(_union.indirect_contents.indirect) + pos; }
     bool is_direct() const { return _size <= N; }
 
     void change_capacity(size_type new_capacity) {
@@ -182,17 +182,17 @@ private:
                 /* FIXME: Because malloc/realloc here won't call new_handler if allocation fails, assert
                     success. These should instead use an allocator or new/delete so that handlers
                     are called as necessary, but performance would be slightly degraded by doing so. */
-                _union.indirect = static_cast<char*>(realloc(_union.indirect, ((size_t)sizeof(T)) * new_capacity));
-                assert(_union.indirect);
-                _union.capacity = new_capacity;
+                _union.indirect_contents.indirect = static_cast<char*>(realloc(_union.indirect_contents.indirect, ((size_t)sizeof(T)) * new_capacity));
+                assert(_union.indirect_contents.indirect);
+                _union.indirect_contents.capacity = new_capacity;
             } else {
                 char* new_indirect = static_cast<char*>(malloc(((size_t)sizeof(T)) * new_capacity));
                 assert(new_indirect);
                 T* src = direct_ptr(0);
                 T* dst = reinterpret_cast<T*>(new_indirect);
                 memcpy(dst, src, size() * sizeof(T));
-                _union.indirect = new_indirect;
-                _union.capacity = new_capacity;
+                _union.indirect_contents.indirect = new_indirect;
+                _union.indirect_contents.capacity = new_capacity;
                 _size += N + 1;
             }
         }
@@ -301,7 +301,7 @@ public:
         if (is_direct()) {
             return N;
         } else {
-            return _union.capacity;
+            return _union.indirect_contents.capacity;
         }
     }
 
@@ -468,8 +468,8 @@ public:
             clear();
         }
         if (!is_direct()) {
-            free(_union.indirect);
-            _union.indirect = nullptr;
+            free(_union.indirect_contents.indirect);
+            _union.indirect_contents.indirect = nullptr;
         }
     }
 
@@ -521,7 +521,7 @@ public:
         if (is_direct()) {
             return 0;
         } else {
-            return ((size_t)(sizeof(T))) * _union.capacity;
+            return ((size_t)(sizeof(T))) * _union.indirect_contents.capacity;
         }
     }