Use allocate in ArenaStlAllocator

src/arena_allocator.hpp

@@ -5,7 +5,6 @@
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
-#include <iomanip>
 #include <iostream>
 #include <new>
 #include <type_traits>
@@ -595,13 +594,11 @@ public:
   T *allocate(size_type n) {
     if (n == 0)
       return nullptr;
-    return static_cast<T *>(arena_->allocate_raw(n * sizeof(T), alignof(T)));
+    return arena_->allocate<T>(n);
   }
 
-  void deallocate(T *ptr, size_type n) noexcept {
+  void deallocate(T *, size_type) noexcept {
     // Arena allocator doesn't support individual deallocation
-    (void)ptr;
-    (void)n;
   }
 
   template <typename U>