libcxx/test/std/diagnostics/syserr/is_error_condition_enum.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14
  10
  11 // <system_error>
  12
  13 // template <class T> constexpr bool is_error_condition_enum_v;
  14
  15 #include <cstddef>
  16 #include <string>
  17 #include <system_error>
  18 #include <type_traits>
  19
  20 #include "test_macros.h"
  21
  22 template <bool Expected, class T>
  23 void
  24 test()
  25 {
  26     static_assert((std::is_error_condition_enum<T>::value == Expected), "");
  27 #if TEST_STD_VER > 14
  28     static_assert((std::is_error_condition_enum_v<T>        == Expected), "");
  29     ASSERT_SAME_TYPE(decltype(std::is_error_condition_enum_v<T>), const bool);
  30 #endif
  31 }
  32
  33 class A {
  34     A();
  35     operator std::error_condition () const { return std::error_condition(); }
  36 };
  37
  38 // Specialize the template for my class
  39 template <>
  40 struct std::is_error_condition_enum<A> : public std::true_type {};
  41
  42 int main(int, char**)
  43 {
  44     test<false, void>();
  45     test<false, int>();
  46     test<false, std::nullptr_t>();
  47     test<false, std::string>();
  48
  49     test<true, A>();
  50
  51   return 0;
  52 }