Fix compiler error on MSVC with c++latest (#3954)

src/lockfree.h

@@ -30,32 +30,38 @@
  * we use this to avoid instantiating multiple free lists for objects of the
  * same size and it can be replaced by a variable template in C++14
  *
- * template <std::size_t TSize, size_t CAPACITY>
- * boost::lockfree::stack<void*, boost::lockfree::capacity<CAPACITY> lockfreeFreeList;
+ * template <size_t TSize, size_t Capacity>
+ * boost::lockfree::stack<void*, boost::lockfree::capacity<Capacity> lockfreeFreeList;
  */
-template <std::size_t TSize, size_t CAPACITY>
+template <size_t TSize, size_t Capacity>
 struct LockfreeFreeList
 {
-	using FreeList = boost::lockfree::stack<void*, boost::lockfree::capacity<CAPACITY>>;
+	using FreeList = boost::lockfree::stack<void*, boost::lockfree::capacity<Capacity>>;
 	static FreeList& get()
 	{
 		static FreeList freeList;
 		return freeList;
 	}
 };
 
-template <typename T, size_t CAPACITY>
-class LockfreePoolingAllocator : public std::allocator<T>
+template <typename T, size_t Capacity>
+class LockfreePoolingAllocator
 {
 	public:
+		template <class U>
+		struct rebind
+		{
+			using other = LockfreePoolingAllocator<U, Capacity>;
+		};
+
 		LockfreePoolingAllocator() = default;
 
-		template <typename U, class = typename std::enable_if<!std::is_same<U, T>::value>::type>
-		explicit constexpr LockfreePoolingAllocator(const U&) {}
+		template <typename U>
+		explicit constexpr LockfreePoolingAllocator(const LockfreePoolingAllocator<U, Capacity>&) {}
 		using value_type = T;
 
 		T* allocate(size_t) const {
-			auto& inst = LockfreeFreeList<sizeof(T), CAPACITY>::get();
+			auto& inst = LockfreeFreeList<sizeof(T), Capacity>::get();
 			void* p; // NOTE: p doesn't have to be initialized
 			if (!inst.pop(p)) {
 				//Acquire memory without calling the constructor of T
@@ -65,7 +71,7 @@ class LockfreePoolingAllocator : public std::allocator<T>
 		}
 
 		void deallocate(T* p, size_t) const {
-			auto& inst = LockfreeFreeList<sizeof(T), CAPACITY>::get();
+			auto& inst = LockfreeFreeList<sizeof(T), Capacity>::get();
 			if (!inst.bounded_push(p)) {
 				//Release memory without calling the destructor of T
 				//(it has already been called at this point)