std::numpunct::~numpunct

From cppreference.com
< cpplrm; | localelrm; | numpunct
Defined in header <locale>
protected: ~numpunct();

Destructs a std::numpunct facet. This destructor is protected and virtual (due to base class destructor being virtual). An object of type std::numpunct, like most facets, can only be destroyed when the last std::locale object that implements this facet goes out of scope or if a user-defined class is derived from std::numpunct and implements a public destructor.

Example

#include <iostream>
#include <locale>
struct Destructible_numpunct : public std::numpunct<wchar_t>
{
    Destructible_numpunct(std::size_t refs = 0) : numpunct(refs) {}
    // note: the implicit destructor is public
};
int main()
{
    Destructible_numpunct dc;
    // std::numpunct<wchar_t> c;  // compile error: protected destructor
}