std::set custom ordering with composition, C++ (clang)

std::set custom ordering with composition

#include <iostream>
#include <unordered_set>
#include <unordered_map>
#include <set>
 
struct S
{
    S(int order) : order(order) {}
    int order;
};
 
namespace std
{
    template<> struct less<S*>
    {
        bool operator()(const S* lhs, const S* rhs) const noexcept
        {
            std::cout << "mijau\n";
            return lhs->order < rhs->order;
        }
    };
}

void f()
{
    S x(1);
    S y(2);
    S z(3);
    std::set<S*> modules = {&x, &y, &z};
    for(const auto& module : modules)
        std::cout << module->order << '\n';
    
    std::unordered_map<int, std::set<S*>> map;
    map[0];
}

void g()
{
    const auto comparator = [](const S* lhs, const S* rhs) -> bool {
        std::cout << "mijau\n";        
        return lhs->order < rhs->order;
    };
    
    S x(1);
    S y(2);
    S z(3);
    auto modules = std::set<S*, decltype(comparator)>({&x, &y, &z}, comparator);
    for(const auto& module : modules)
        std::cout << module->order << '\n';
    
    std::unordered_map<int, std::set<S*, decltype(comparator)>> map;
    //map[0]; // breaks
}
 
int main()
{
    f();
    g();

}


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