libcxx/test/std/containers/sequences/array/indexing.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 // reference operator[](size_type); // constexpr in C++17
  12 // Libc++ marks it as noexcept
  13
  14 #include <array>
  15 #include <cassert>
  16
  17 #include "test_macros.h"
  18
  19 // std::array is explicitly allowed to be initialized with A a = { init-list };.
  20 // Disable the missing braces warning for this reason.
  21 #include "disable_missing_braces_warning.h"
  22
  23
  24 TEST_CONSTEXPR_CXX17 bool tests()
  25 {
  26     {
  27         typedef double T;
  28         typedef std::array<T, 3> C;
  29         C c = {1, 2, 3.5};
  30         LIBCPP_ASSERT_NOEXCEPT(c[0]);
  31         ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
  32         C::reference r1 = c[0];
  33         assert(r1 == 1);
  34         r1 = 5.5;
  35         assert(c.front() == 5.5);
  36
  37         C::reference r2 = c[2];
  38         assert(r2 == 3.5);
  39         r2 = 7.5;
  40         assert(c.back() == 7.5);
  41     }
  42
  43     // Test operator[] "works" on zero sized arrays
  44     {
  45         {
  46             typedef double T;
  47             typedef std::array<T, 0> C;
  48             C c = {};
  49             LIBCPP_ASSERT_NOEXCEPT(c[0]);
  50             ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
  51             if (c.size() > (0)) { // always false
  52               C::reference r = c[0];
  53               (void)r;
  54             }
  55         }
  56         {
  57             typedef double T;
  58             typedef std::array<const T, 0> C;
  59             C c = {};
  60             LIBCPP_ASSERT_NOEXCEPT(c[0]);
  61             ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
  62             if (c.size() > (0)) { // always false
  63               C::reference r = c[0];
  64               (void)r;
  65             }
  66         }
  67     }
  68
  69     return true;
  70 }
  71
  72 int main(int, char**)
  73 {
  74     tests();
  75 #if TEST_STD_VER >= 17
  76     static_assert(tests(), "");
  77 #endif
  78     return 0;
  79 }