ceph/src/boost/libs/optional/test/optional_test_path_assignment.cpp

   1 // Copyright (C) 2019 Andrzej Krzemienski.
   2 //
   3 // Use, modification, and distribution is subject to the Boost Software
   4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org/lib/optional for documentation.
   8 //
   9 // You are welcome to contact the author at:
  10 //  akrzemi1@gmail.com
  11
  12 #include "boost/optional/optional.hpp"
  13
  14 #ifdef __BORLANDC__
  15 #pragma hdrstop
  16 #endif
  17
  18 #ifndef BOOST_OPTIONAL_DETAIL_NO_IS_CONSTRUCTIBLE_TRAIT
  19 #ifndef BOOST_OPTIONAL_DETAIL_NO_SFINAE_FRIENDLY_CONSTRUCTORS
  20 template <typename, typename>
  21 struct void_t
  22 {
  23   typedef void type;
  24 };
  25
  26
  27 template <typename T, typename = void>
  28 struct trait
  29 {
  30 };
  31
  32 // the following trait emulates properties std::iterator_traits
  33 template <typename T>
  34 struct trait<T, BOOST_DEDUCED_TYPENAME void_t<BOOST_DEDUCED_TYPENAME T::value_type,
  35                                               BOOST_DEDUCED_TYPENAME boost::enable_if<boost::is_constructible<T, T&> >::type
  36                                              >::type>
  37 {
  38   typedef BOOST_DEDUCED_TYPENAME T::value_type value_type;
  39 };
  40
  41 // This class emulates the properties of std::filesystem::path
  42 struct Path
  43 {
  44
  45 #if __cplusplus >= 201103
  46     template <typename T, typename = BOOST_DEDUCED_TYPENAME trait<T>::value_type>
  47         Path(T const&);
  48 #else
  49   template <typename T>
  50     Path(T const&, BOOST_DEDUCED_TYPENAME trait<T>::value_type* = 0);
  51 #endif
  52
  53 };
  54 #endif
  55 #endif
  56
  57
  58 int main()
  59 {
  60 #ifndef BOOST_OPTIONAL_DETAIL_NO_IS_CONSTRUCTIBLE_TRAIT
  61 #ifndef BOOST_OPTIONAL_DETAIL_NO_SFINAE_FRIENDLY_CONSTRUCTORS
  62
  63     boost::optional<Path> optFs1;
  64     boost::optional<Path> optFs2;
  65
  66     optFs1 = optFs2;
  67
  68     // the following still fails although it shouldn't
  69     //BOOST_STATIC_ASSERT((std::is_copy_constructible<boost::optional<Path>>::value));
  70
  71 #endif
  72 #endif
  73 }