libcxx/test/std/containers/sequences/array/array.cons/deduct.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 // UNSUPPORTED: c++03, c++11, c++14
  11
  12 // template <class T, class... U>
  13 //   array(T, U...) -> array<T, 1 + sizeof...(U)>;
  14 //
  15 //  Requires: (is_same_v<T, U> && ...) is true. Otherwise the program is ill-formed.
  16
  17 #include <array>
  18 #include <cassert>
  19 #include <cstddef>
  20
  21 #include "test_macros.h"
  22
  23 constexpr bool tests()
  24 {
  25     //  Test the explicit deduction guides
  26     {
  27         std::array arr{1,2,3};  // array(T, U...)
  28         static_assert(std::is_same_v<decltype(arr), std::array<int, 3>>, "");
  29         assert(arr[0] == 1);
  30         assert(arr[1] == 2);
  31         assert(arr[2] == 3);
  32     }
  33
  34     {
  35         const long l1 = 42;
  36         std::array arr{1L, 4L, 9L, l1}; // array(T, U...)
  37         static_assert(std::is_same_v<decltype(arr)::value_type, long>, "");
  38         static_assert(arr.size() == 4, "");
  39         assert(arr[0] == 1);
  40         assert(arr[1] == 4);
  41         assert(arr[2] == 9);
  42         assert(arr[3] == l1);
  43     }
  44
  45     //  Test the implicit deduction guides
  46     {
  47         std::array<double, 2> source = {4.0, 5.0};
  48         std::array arr(source);   // array(array)
  49         static_assert(std::is_same_v<decltype(arr), decltype(source)>, "");
  50         static_assert(std::is_same_v<decltype(arr), std::array<double, 2>>, "");
  51         assert(arr[0] == 4.0);
  52         assert(arr[1] == 5.0);
  53     }
  54
  55     return true;
  56 }
  57
  58 int main(int, char**)
  59 {
  60     tests();
  61     static_assert(tests(), "");
  62     return 0;
  63 }