class_of_constraints.cpp 1.4 KB

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  1. /*
  2. Copyright Barrett Adair 2016-2017
  3. Distributed under the Boost Software License, Version 1.0.
  4. (See accompanying file LICENSE.md or copy at http ://boost.org/LICENSE_1_0.txt)
  5. */
  6. #include <boost/callable_traits/class_of.hpp>
  7. #include "test.hpp"
  8. struct foo;
  9. template<typename T>
  10. struct is_substitution_failure_class_of {
  11. template<typename>
  12. static auto test(...) -> std::true_type;
  13. template<typename A,
  14. typename std::remove_reference<
  15. TRAIT(class_of, A)>::type* = nullptr>
  16. static auto test(int) -> std::false_type;
  17. static constexpr bool value = decltype(test<T>(0))::value;
  18. };
  19. int main() {
  20. auto lambda = [](){};
  21. CT_ASSERT(is_substitution_failure_class_of<decltype(lambda)>::value);
  22. CT_ASSERT(is_substitution_failure_class_of<decltype(lambda)&>::value);
  23. CT_ASSERT(is_substitution_failure_class_of<void>::value);
  24. CT_ASSERT(is_substitution_failure_class_of<void*>::value);
  25. CT_ASSERT(is_substitution_failure_class_of<int>::value);
  26. CT_ASSERT(is_substitution_failure_class_of<int &>::value);
  27. CT_ASSERT(is_substitution_failure_class_of<int()>::value);
  28. CT_ASSERT(is_substitution_failure_class_of<int(*)()>::value);
  29. CT_ASSERT(is_substitution_failure_class_of<int(**)()>::value);
  30. CT_ASSERT(is_substitution_failure_class_of<int(&)()>::value);
  31. CT_ASSERT(is_substitution_failure_class_of<int (foo::** const)()>::value);
  32. }