libcxx/test/std/numerics/bit/bit.endian/endian.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++98, c++03, c++11, c++14, c++17
  10
  11 // enum class endian;
  12 // <bit>
  13
  14 #include <bit>
  15 #include <cstring>
  16 #include <cassert>
  17 #include <cstdint>
  18
  19 #include "test_macros.h"
  20
  21 int main(int, char**) {
  22     static_assert(std::is_enum<std::endian>::value, "");
  23
  24 // Check that E is a scoped enum by checking for conversions.
  25     typedef std::underlying_type<std::endian>::type UT;
  26     static_assert(!std::is_convertible<std::endian, UT>::value, "");
  27
  28 // test that the enumeration values exist
  29     static_assert( std::endian::little == std::endian::little );
  30     static_assert( std::endian::big    == std::endian::big );
  31     static_assert( std::endian::native == std::endian::native );
  32     static_assert( std::endian::little != std::endian::big );
  33
  34 //  Technically not required, but true on all existing machines
  35     static_assert( std::endian::native == std::endian::little ||
  36                    std::endian::native == std::endian::big );
  37
  38 //  Try to check at runtime
  39     {
  40     uint32_t i = 0x01020304;
  41     char c[4];
  42     static_assert(sizeof(i) == sizeof(c));
  43     std::memcpy(c, &i, sizeof(c));
  44
  45     assert ((c[0] == 1) == (std::endian::native == std::endian::big));
  46     }
  47
  48   return 0;
  49 }