libcxx/test/std/containers/views/mdspan/layout_right/ctor.layout_left.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 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
  10
  11 // <mdspan>
  12
  13 // template<class OtherExtents>
  14 //   constexpr explicit(!is_convertible_v<OtherExtents, extents_type>)
  15 //     mapping(const layout_left::mapping<OtherExtents>&) noexcept;
  16
  17 // Constraints:
  18 //   - extents_type::rank() <= 1 is true, and
  19 //   - is_constructible_v<extents_type, OtherExtents> is true.
  20 //
  21 // Preconditions: other.required_span_size() is representable as a value of type index_type
  22
  23 #include <mdspan>
  24 #include <type_traits>
  25 #include <cassert>
  26 #include <limits>
  27
  28 #include "test_macros.h"
  29
  30 template <class To, class From>
  31 constexpr void test_implicit_conversion(To dest, From src) {
  32   assert(dest.extents() == src.extents());
  33 }
  34
  35 template <bool implicit, class ToE, class FromE>
  36 constexpr void test_conversion(FromE src_exts) {
  37   using To   = std::layout_right::mapping<ToE>;
  38   using From = std::layout_left::mapping<FromE>;
  39   From src(src_exts);
  40
  41   ASSERT_NOEXCEPT(To(src));
  42   To dest(src);
  43
  44   assert(dest.extents() == src.extents());
  45   if constexpr (implicit) {
  46     dest = src;
  47     assert(dest.extents() == src.extents());
  48     test_implicit_conversion<To, From>(src, src);
  49   }
  50 }
  51
  52 template <class T1, class T2>
  53 constexpr void test_conversion() {
  54   constexpr size_t D = std::dynamic_extent;
  55   constexpr bool idx_convertible =
  56       static_cast<size_t>(std::numeric_limits<T1>::max()) >= static_cast<size_t>(std::numeric_limits<T2>::max());
  57
  58   // clang-format off
  59   test_conversion<idx_convertible && true,  std::extents<T1>>(std::extents<T2>());
  60   test_conversion<idx_convertible && true,  std::extents<T1, D>>(std::extents<T2, D>(5));
  61   test_conversion<idx_convertible && false, std::extents<T1, 5>>(std::extents<T2, D>(5));
  62   test_conversion<idx_convertible && true,  std::extents<T1, 5>>(std::extents<T2, 5>());
  63   // clang-format on
  64 }
  65
  66 template <class IdxT, size_t... Extents>
  67 using lr_mapping_t = std::layout_right::mapping<std::extents<IdxT, Extents...>>;
  68 template <class IdxT, size_t... Extents>
  69 using ll_mapping_t = std::layout_left::mapping<std::extents<IdxT, Extents...>>;
  70
  71 constexpr void test_no_implicit_conversion() {
  72   constexpr size_t D = std::dynamic_extent;
  73
  74   // Sanity check that one static to dynamic conversion works
  75   static_assert(std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int, 5>>);
  76   static_assert(std::is_convertible_v<ll_mapping_t<int, 5>, lr_mapping_t<int, D>>);
  77
  78   // Check that dynamic to static conversion only works explicitly
  79   static_assert(std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<int, D>>);
  80   static_assert(!std::is_convertible_v<ll_mapping_t<int, D>, lr_mapping_t<int, 5>>);
  81
  82   // Sanity check that smaller index_type to larger index_type conversion works
  83   static_assert(std::is_constructible_v<lr_mapping_t<size_t, 5>, ll_mapping_t<int, 5>>);
  84   static_assert(std::is_convertible_v<ll_mapping_t<int, 5>, lr_mapping_t<size_t, 5>>);
  85
  86   // Check that larger index_type to smaller index_type conversion works explicitly only
  87   static_assert(std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<size_t, 5>>);
  88   static_assert(!std::is_convertible_v<ll_mapping_t<size_t, 5>, lr_mapping_t<int, 5>>);
  89 }
  90
  91 constexpr void test_rank_mismatch() {
  92   constexpr size_t D = std::dynamic_extent;
  93
  94   static_assert(!std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int>>);
  95   static_assert(!std::is_constructible_v<lr_mapping_t<int>, ll_mapping_t<int, D, D>>);
  96   static_assert(!std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int, D, D>>);
  97   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D, D>, ll_mapping_t<int, D, D>>);
  98 }
  99
 100 constexpr void test_static_extent_mismatch() {
 101   static_assert(!std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<int, 4>>);
 102 }
 103
 104 constexpr void test_rank_greater_one() {
 105   constexpr size_t D = std::dynamic_extent;
 106
 107   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D>, ll_mapping_t<int, D, D>>);
 108   static_assert(!std::is_constructible_v<lr_mapping_t<int, 1, 1>, ll_mapping_t<int, 1, 1>>);
 109   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D, D>, ll_mapping_t<int, D, D, D>>);
 110 }
 111
 112 constexpr bool test() {
 113   test_conversion<int, int>();
 114   test_conversion<int, size_t>();
 115   test_conversion<size_t, int>();
 116   test_conversion<size_t, long>();
 117   test_no_implicit_conversion();
 118   test_rank_mismatch();
 119   test_static_extent_mismatch();
 120   test_rank_greater_one();
 121   return true;
 122 }
 123
 124 int main(int, char**) {
 125   test();
 126   static_assert(test());
 127   return 0;
 128 }