libstdc++-v3/testsuite/20_util/common_type/requirements/sfinae_friendly_2.cc

   1 // { dg-do compile { target c++11 } }
   2
   3 // Copyright (C) 2012-2021 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20 #include <type_traits>
  21 #include <array>
  22 #include <utility>
  23
  24 template<typename... Args>
  25 constexpr
  26 std::array<typename std::common_type<Args...>::type,
  27   sizeof...(Args)>
  28 make_array(Args&&... args)  // { dg-error "no type.*common_type<>" }
  29 {
  30   typedef typename std::common_type<Args...>::type CT;
  31   return std::array<CT, sizeof...(Args)>{static_cast<CT>
  32       (std::forward<Args>(args))...};
  33 }
  34
  35 void test01()
  36 {
  37   constexpr auto a1 = make_array(0);
  38   constexpr auto a2 = make_array(0, 1.2);
  39   constexpr auto a3 = make_array(5, true, 3.1415f, 'c');
  40
  41   int i{};
  42   double d{1.2};
  43   float f{3.1415f};
  44
  45   auto b1 = make_array(i);
  46   auto b2 = make_array(i, 1.2);
  47   auto b3 = make_array(i, d);
  48   auto b4 = make_array(0, d);
  49   auto b5 = make_array(i, true, f, 'c');
  50
  51   static_assert(std::is_same<decltype(a1), const std::array<int, 1>>(), "");
  52   static_assert(std::is_same<decltype(a2), const std::array<double, 2>>(), "");
  53   static_assert(std::is_same<decltype(a3), const std::array<float, 4>>(), "");
  54
  55   static_assert(std::is_same<decltype(b1), std::array<int, 1>>(), "");
  56   static_assert(std::is_same<decltype(b2), std::array<double, 2>>(), "");
  57   static_assert(std::is_same<decltype(b3), std::array<double, 2>>(), "");
  58   static_assert(std::is_same<decltype(b4), std::array<double, 2>>(), "");
  59   static_assert(std::is_same<decltype(b5), std::array<float, 4>>(), "");
  60 }
  61
  62 void test02()
  63 {
  64   make_array(); // { dg-error "no matching function" }
  65 }
  66 // { dg-prune-output "substitution" }
  67 // { dg-prune-output "include" }