libcxx/test/std/diagnostics/syserr/is_error_code_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
  10
  11 // <system_error>
  12
  13 // template <> struct is_error_code_enum<> : public false_type {};
  14
  15 #include <cstddef>
  16 #include <string>
  17 #include <system_error>
  18
  19 #include "test_macros.h"
  20
  21 template <bool Expected, class T>
  22 void
  23 test()
  24 {
  25     static_assert((std::is_error_code_enum<T>::value == Expected), "");
  26 #if TEST_STD_VER > 14
  27     static_assert((std::is_error_code_enum_v<T>      == Expected), "");
  28     ASSERT_SAME_TYPE(decltype(std::is_error_code_enum_v<T>), const bool);
  29 #endif
  30 }
  31
  32 class A {
  33     A();
  34     operator std::error_code () const { return std::error_code(); }
  35 };
  36
  37 // Specialize the template for my class
  38 template <>
  39 struct std::is_error_code_enum<A> : public std::true_type {};
  40
  41 int main(int, char**)
  42 {
  43     test<false, void>();
  44     test<false, int>();
  45     test<false, std::nullptr_t>();
  46     test<false, std::string>();
  47
  48     test<true, A>();
  49
  50   return 0;
  51 }