cpp_weekly/multiple_destructors/after.cpp at master · jhthorp/cpp_weekly · GitHub

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#include <utility>
#include <string>
#include <type_traits>

template<typename Contained>
struct Optional
{
  union { Contained data; };
  bool initialized = false;

  constexpr Optional &operator=(Contained &&data) {
      this->data = std::move(data);
      initialized = true;
      return *this;
  }

  constexpr ~Optional() requires(!std::is_trivially_destructible_v<Contained>) {
      if (initialized) {
          data.~Contained();
      }
  }

  constexpr ~Optional() = default;

};

int main()
{
    Optional<int> obj;
    obj = 5;

    static_assert(std::is_trivially_destructible_v<Optional<int>>);
    static_assert(!std::is_trivially_destructible_v<Optional<std::string>>);
}