text: //===----------------------------------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  // UNSUPPORTED: c++03, c++11, c++14, c++17
  // UNSUPPORTED: libcpp-has-no-incomplete-ranges
  
  // AppleClang 12.0.0 doesn't fully support ranges/concepts
  // XFAIL: apple-clang-12.0.0
  
  // <span>
  
  // template <class ElementType, size_t Extent>
  //     span<const byte,
  //          Extent == dynamic_extent
  //              ? dynamic_extent
  //              : sizeof(ElementType) * Extent>
  //     as_bytes(span<ElementType, Extent> s) noexcept;
  
  
  #include <span>
  #include <cassert>
  #include <string>
  
  #include "test_macros.h"
  
  template<typename Span>
  void testRuntimeSpan(Span sp)
  {
      ASSERT_NOEXCEPT(std::as_bytes(sp));
  
      auto spBytes = std::as_bytes(sp);
      using SB = decltype(spBytes);
      ASSERT_SAME_TYPE(const std::byte, typename SB::element_type);
  
      if constexpr (sp.extent == std::dynamic_extent)
          assert(spBytes.extent == std::dynamic_extent);
      else
          assert(spBytes.extent == sizeof(typename Span::element_type) * sp.extent);
  
      assert((void *) spBytes.data() == (void *) sp.data());
      assert(spBytes.size() == sp.size_bytes());
  }
  
  struct A{};
  int iArr2[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9};
  
  int main(int, char**)
  {
      testRuntimeSpan(std::span<int>        ());
      testRuntimeSpan(std::span<long>       ());
      testRuntimeSpan(std::span<double>     ());
      testRuntimeSpan(std::span<A>          ());
      testRuntimeSpan(std::span<std::string>());
  
      testRuntimeSpan(std::span<int, 0>        ());
      testRuntimeSpan(std::span<long, 0>       ());
      testRuntimeSpan(std::span<double, 0>     ());
      testRuntimeSpan(std::span<A, 0>          ());
      testRuntimeSpan(std::span<std::string, 0>());
  
      testRuntimeSpan(std::span<int>(iArr2, 1));
      testRuntimeSpan(std::span<int>(iArr2, 2));
      testRuntimeSpan(std::span<int>(iArr2, 3));
      testRuntimeSpan(std::span<int>(iArr2, 4));
      testRuntimeSpan(std::span<int>(iArr2, 5));
  
      testRuntimeSpan(std::span<int, 1>(iArr2 + 5, 1));
      testRuntimeSpan(std::span<int, 2>(iArr2 + 4, 2));
      testRuntimeSpan(std::span<int, 3>(iArr2 + 3, 3));
      testRuntimeSpan(std::span<int, 4>(iArr2 + 2, 4));
      testRuntimeSpan(std::span<int, 5>(iArr2 + 1, 5));
  
      std::string s;
      testRuntimeSpan(std::span<std::string>(&s, (std::size_t) 0));
      testRuntimeSpan(std::span<std::string>(&s, 1));
  
    return 0;
  }
  