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I was reading Why is there no reallocation functionality in C++ allocators? and Is it possible to create an array on the heap at run-time, and then allocate more space whenever needed?, which clearly state that reallocation of a dynamic array of objects is impossible.
However, in The C++ Standard Library by Josuttis, it states an Allocator, allocator, has a function allocate with the following syntax
pointer allocator::allocate(size_type num, allocator<void>::pointer hint = 0)
where the hint has an implementation defined meaning, which may be used to help improve performance.
Are there any implementations that take advantage of this?