The rebind struct here is mandatory because we use non type template arguments for PoolAllocator. See https://en.cppreference.com/w/cpp/named_req/Allocator#cite_note-2
Declared in <support/allocators/pool.h>
template<typename U>
struct rebind;| Name | Description |
|---|---|
other | The PoolAllocator type rebound to allocate objects of type U. |