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 <cassert>
  24 #include <cstddef>
  25 #include <limits>
  26 #include <mdspan>
  27 #include <span> // dynamic_extent
  28 #include <type_traits>
  29
  30 #include "test_macros.h"
  31
  32 template <class To, class From>
  33 constexpr void test_implicit_conversion(To dest, From src) {
  34   assert(dest.extents() == src.extents());
  35 }
  36
  37 template <bool implicit, class ToE, class FromE>
  38 constexpr void test_conversion(FromE src_exts) {
  39   using To   = std::layout_right::mapping<ToE>;
  40   using From = std::layout_left::mapping<FromE>;
  41   From src(src_exts);
  42
  43   ASSERT_NOEXCEPT(To(src));
  44   To dest(src);
  45
  46   assert(dest.extents() == src.extents());
  47   if constexpr (implicit) {
  48     dest = src;
  49     assert(dest.extents() == src.extents());
  50     test_implicit_conversion<To, From>(src, src);
  51   }
  52 }
  53
  54 template <class T1, class T2>
  55 constexpr void test_conversion() {
  56   constexpr size_t D = std::dynamic_extent;
  57   constexpr bool idx_convertible =
  58       static_cast<size_t>(std::numeric_limits<T1>::max()) >= static_cast<size_t>(std::numeric_limits<T2>::max());
  59
  60   // clang-format off
  61   test_conversion<idx_convertible && true,  std::extents<T1>>(std::extents<T2>());
  62   test_conversion<idx_convertible && true,  std::extents<T1, D>>(std::extents<T2, D>(5));
  63   test_conversion<idx_convertible && false, std::extents<T1, 5>>(std::extents<T2, D>(5));
  64   test_conversion<idx_convertible && true,  std::extents<T1, 5>>(std::extents<T2, 5>());
  65   // clang-format on
  66 }
  67
  68 template <class IdxT, size_t... Extents>
  69 using lr_mapping_t = std::layout_right::mapping<std::extents<IdxT, Extents...>>;
  70 template <class IdxT, size_t... Extents>
  71 using ll_mapping_t = std::layout_left::mapping<std::extents<IdxT, Extents...>>;
  72
  73 constexpr void test_no_implicit_conversion() {
  74   constexpr size_t D = std::dynamic_extent;
  75
  76   // Sanity check that one static to dynamic conversion works
  77   static_assert(std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int, 5>>);
  78   static_assert(std::is_convertible_v<ll_mapping_t<int, 5>, lr_mapping_t<int, D>>);
  79
  80   // Check that dynamic to static conversion only works explicitly
  81   static_assert(std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<int, D>>);
  82   static_assert(!std::is_convertible_v<ll_mapping_t<int, D>, lr_mapping_t<int, 5>>);
  83
  84   // Sanity check that smaller index_type to larger index_type conversion works
  85   static_assert(std::is_constructible_v<lr_mapping_t<size_t, 5>, ll_mapping_t<int, 5>>);
  86   static_assert(std::is_convertible_v<ll_mapping_t<int, 5>, lr_mapping_t<size_t, 5>>);
  87
  88   // Check that larger index_type to smaller index_type conversion works explicitly only
  89   static_assert(std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<size_t, 5>>);
  90   static_assert(!std::is_convertible_v<ll_mapping_t<size_t, 5>, lr_mapping_t<int, 5>>);
  91 }
  92
  93 constexpr void test_rank_mismatch() {
  94   constexpr size_t D = std::dynamic_extent;
  95
  96   static_assert(!std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int>>);
  97   static_assert(!std::is_constructible_v<lr_mapping_t<int>, ll_mapping_t<int, D, D>>);
  98   static_assert(!std::is_constructible_v<lr_mapping_t<int, D>, ll_mapping_t<int, D, D>>);
  99   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D, D>, ll_mapping_t<int, D, D>>);
 100 }
 101
 102 constexpr void test_static_extent_mismatch() {
 103   static_assert(!std::is_constructible_v<lr_mapping_t<int, 5>, ll_mapping_t<int, 4>>);
 104 }
 105
 106 constexpr void test_rank_greater_one() {
 107   constexpr size_t D = std::dynamic_extent;
 108
 109   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D>, ll_mapping_t<int, D, D>>);
 110   static_assert(!std::is_constructible_v<lr_mapping_t<int, 1, 1>, ll_mapping_t<int, 1, 1>>);
 111   static_assert(!std::is_constructible_v<lr_mapping_t<int, D, D, D>, ll_mapping_t<int, D, D, D>>);
 112 }
 113
 114 constexpr bool test() {
 115   test_conversion<int, int>();
 116   test_conversion<int, size_t>();
 117   test_conversion<size_t, int>();
 118   test_conversion<size_t, long>();
 119   test_no_implicit_conversion();
 120   test_rank_mismatch();
 121   test_static_extent_mismatch();
 122   test_rank_greater_one();
 123   return true;
 124 }
 125
 126 int main(int, char**) {
 127   test();
 128   static_assert(test());
 129   return 0;
 130 }