libcxx/test/std/containers/sequences/array/front_back_const.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 // <array>
  10
  11 // const_reference front() const; // constexpr in C++14
  12 // const_reference back() const;  // constexpr in C++14
  13
  14 #include <array>
  15 #include <cassert>
  16
  17 #include "test_macros.h"
  18
  19 TEST_CONSTEXPR_CXX14 bool tests()
  20 {
  21     {
  22         typedef double T;
  23         typedef std::array<T, 3> C;
  24         C const c = {1, 2, 3.5};
  25         C::const_reference r1 = c.front();
  26         assert(r1 == 1);
  27
  28         C::const_reference r2 = c.back();
  29         assert(r2 == 3.5);
  30     }
  31     {
  32         typedef double T;
  33         typedef std::array<T, 0> C;
  34         C const c = {};
  35         ASSERT_SAME_TYPE(decltype(c.back()), C::const_reference);
  36         LIBCPP_ASSERT_NOEXCEPT(c.back());
  37         ASSERT_SAME_TYPE(decltype(c.front()), C::const_reference);
  38         LIBCPP_ASSERT_NOEXCEPT(c.front());
  39         if (c.size() > (0)) { // always false
  40             TEST_IGNORE_NODISCARD c.front();
  41             TEST_IGNORE_NODISCARD c.back();
  42         }
  43     }
  44     {
  45         typedef double T;
  46         typedef std::array<const T, 0> C;
  47         C const c = {};
  48         ASSERT_SAME_TYPE(decltype(c.back()), C::const_reference);
  49         LIBCPP_ASSERT_NOEXCEPT(c.back());
  50         ASSERT_SAME_TYPE(decltype(c.front()), C::const_reference);
  51         LIBCPP_ASSERT_NOEXCEPT(c.front());
  52         if (c.size() > (0)) {
  53             TEST_IGNORE_NODISCARD c.front();
  54             TEST_IGNORE_NODISCARD c.back();
  55         }
  56     }
  57
  58     return true;
  59 }
  60
  61 int main(int, char**)
  62 {
  63     tests();
  64 #if TEST_STD_VER >= 14
  65     static_assert(tests(), "");
  66 #endif
  67     return 0;
  68 }