libcxx/test/std/containers/views/mdspan/extents/ctor_from_integral.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 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
   9
  10 // <mdspan>
  11
  12 // Test construction from integral:
  13 //
  14 // template<class ... OtherIndexTypes>
  15 //     constexpr explicit extents(OtherIndexTypes ... exts) noexcept;
  16 //
  17 // Let N be sizeof...(OtherIndexTypes), and let
  18 // exts_arr be array<index_type, N>{static_cast<index_type>(std::move(exts))...}.
  19 //
  20 // Constraints:
  21 //   * (is_convertible_v<OtherIndexTypes, index_type> && ...) is true,
  22 //   * (is_nothrow_constructible_v<index_type, OtherIndexType> && ...) is true, and
  23 //   * N == rank_dynamic() || N == rank() is true.
  24 //
  25 // Preconditions:
  26 //   * If N != rank_dynamic() is true, exts_arr[r] equals Er for each r for which
  27 //     Er is a static extent, and
  28 //   * either
  29 //     - sizeof...(exts) == 0 is true, or
  30 //     - each element of exts is nonnegative and is representable as a value of type index_type.
  31 //
  32
  33 #include <mdspan>
  34 #include <cassert>
  35 #include <type_traits>
  36
  37 #include "../ConvertibleToIntegral.h"
  38 #include "CtorTestCombinations.h"
  39 #include "test_macros.h"
  40
  41 struct IntegralCtorTest {
  42   template <class E, class AllExtents, class Extents, size_t... Indices>
  43   static constexpr void test_construction(AllExtents all_ext, Extents ext, std::index_sequence<Indices...>) {
  44     // construction from indices
  45     ASSERT_NOEXCEPT(E(ext[Indices]...));
  46     test_runtime_observers(E(ext[Indices]...), all_ext);
  47   }
  48 };
  49
  50 int main(int, char**) {
  51   test_index_type_combo<IntegralCtorTest>();
  52   static_assert(test_index_type_combo<IntegralCtorTest>());
  53
  54   constexpr size_t D = std::dynamic_extent;
  55   using E            = std::extents<int, 1, D, 3, D>;
  56
  57   // check can't construct from too few arguments
  58   static_assert(!std::is_constructible_v<E, int>, "extents constructible from illegal arguments");
  59   // check can't construct from rank_dynamic < #args < rank
  60   static_assert(!std::is_constructible_v<E, int, int, int>, "extents constructible from illegal arguments");
  61   // check can't construct from too many arguments
  62   static_assert(!std::is_constructible_v<E, int, int, int, int, int>, "extents constructible from illegal arguments");
  63
  64   // test construction fails from types not convertible to index_type but convertible to other integer types
  65   static_assert(std::is_convertible_v<IntType, int>, "Test helper IntType unexpectedly not convertible to int");
  66   static_assert(!std::is_constructible_v< std::extents<unsigned long, D>, IntType>,
  67                 "extents constructible from illegal arguments");
  68   return 0;
  69 }