Compile error with vector

[gshirreffs]

With a custom allocator which specifies 16-bit size and difference types, the next_capacity calculation of vector causes an error:

#include <boost/container/vector.hpp>

class CustomAllocator
{
public:
    typedef int value_type;
    typedef value_type* pointer;
    typedef const value_type* const_pointer;
    typedef unsigned short size_type;
    typedef short difference_type;

    pointer allocate(size_type count);
    void deallocate(pointer ptr, size_type count);
};

int main()
{
    boost::container::vector<int, CustomAllocator> test;
    test.push_back(1);
    return 0;
}

Compiling with Visual C++ 2019, the above gives an error at container/detail/next_capacity.hpp(56)

'boost::container::dtl::max_value': no matching overloaded function found

The issue is caused by cur_cap+min_cap automatically widening to int, which then fails to match any max_value implementation. Adding a cast around the addition resolves the issue:

  return max_value(SizeType(Minimum), max_value(SizeType(cur_cap+add_min_cap), min_value(max_cap, new_cap)));