ceph/src/boost/boost/dll/detail/aggressive_ptr_cast.hpp

   1 // Copyright 2014 Renato Tegon Forti, Antony Polukhin.
   2 // Copyright 2015-2017 Antony Polukhin.
   3 //
   4 // Distributed under the Boost Software License, Version 1.0.
   5 // (See accompanying file LICENSE_1_0.txt
   6 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_DLL_DETAIL_AGGRESSIVE_PTR_CAST_HPP
   9 #define BOOST_DLL_DETAIL_AGGRESSIVE_PTR_CAST_HPP
  10
  11 #include <boost/config.hpp>
  12 #ifdef BOOST_HAS_PRAGMA_ONCE
  13 #   pragma once
  14 #endif
  15
  16 #include <boost/core/enable_if.hpp>
  17 #include <boost/static_assert.hpp>
  18 #include <boost/type_traits/is_pointer.hpp>
  19 #include <boost/type_traits/is_member_pointer.hpp>
  20 #include <boost/type_traits/is_void.hpp>
  21 #include <boost/type_traits/is_reference.hpp>
  22 #include <boost/type_traits/remove_pointer.hpp>
  23 #include <boost/type_traits/remove_reference.hpp>
  24 #include <cstring>              // std::memcpy
  25
  26 #if defined(__GNUC__) && defined(__GNUC_MINOR__) && (__GNUC__ * 100 + __GNUC_MINOR__ > 301)
  27 #   pragma GCC system_header
  28 #endif
  29
  30 namespace boost { namespace dll { namespace detail {
  31
  32 // GCC warns when reinterpret_cast between function pointer and object pointer occur.
  33 // This method suppress the warnings and ensures that such casts are safe.
  34 template <class To, class From>
  35 BOOST_FORCEINLINE typename boost::disable_if_c<boost::is_member_pointer<To>::value || boost::is_reference<To>::value || boost::is_member_pointer<From>::value, To>::type
  36     aggressive_ptr_cast(From v) BOOST_NOEXCEPT
  37 {
  38     BOOST_STATIC_ASSERT_MSG(
  39         boost::is_pointer<To>::value && boost::is_pointer<From>::value,
  40         "`agressive_ptr_cast` function must be used only for pointer casting."
  41     );
  42
  43     BOOST_STATIC_ASSERT_MSG(
  44         boost::is_void< typename boost::remove_pointer<To>::type >::value
  45         || boost::is_void< typename boost::remove_pointer<From>::type >::value,
  46         "`agressive_ptr_cast` function must be used only for casting to or from void pointers."
  47     );
  48
  49     BOOST_STATIC_ASSERT_MSG(
  50         sizeof(v) == sizeof(To),
  51         "Pointer to function and pointer to object differ in size on your platform."
  52     );
  53
  54     return reinterpret_cast<To>(v);
  55 }
  56
  57 #ifdef BOOST_MSVC
  58 #   pragma warning(push)
  59 #   pragma warning(disable: 4172) // "returning address of local variable or temporary" but **v is not local!
  60 #endif
  61
  62 template <class To, class From>
  63 BOOST_FORCEINLINE typename boost::disable_if_c<!boost::is_reference<To>::value || boost::is_member_pointer<From>::value, To>::type
  64     aggressive_ptr_cast(From v) BOOST_NOEXCEPT
  65 {
  66     BOOST_STATIC_ASSERT_MSG(
  67         boost::is_pointer<From>::value,
  68         "`agressive_ptr_cast` function must be used only for pointer casting."
  69     );
  70
  71     BOOST_STATIC_ASSERT_MSG(
  72         boost::is_void< typename boost::remove_pointer<From>::type >::value,
  73         "`agressive_ptr_cast` function must be used only for casting to or from void pointers."
  74     );
  75
  76     BOOST_STATIC_ASSERT_MSG(
  77         sizeof(v) == sizeof(typename boost::remove_reference<To>::type*),
  78         "Pointer to function and pointer to object differ in size on your platform."
  79     );
  80     return static_cast<To>(
  81         **reinterpret_cast<typename boost::remove_reference<To>::type**>(
  82             v
  83         )
  84     );
  85 }
  86
  87 #ifdef BOOST_MSVC
  88 #   pragma warning(pop)
  89 #endif
  90
  91 template <class To, class From>
  92 BOOST_FORCEINLINE typename boost::disable_if_c<!boost::is_member_pointer<To>::value || boost::is_member_pointer<From>::value, To>::type
  93     aggressive_ptr_cast(From v) BOOST_NOEXCEPT
  94 {
  95     BOOST_STATIC_ASSERT_MSG(
  96         boost::is_pointer<From>::value,
  97         "`agressive_ptr_cast` function must be used only for pointer casting."
  98     );
  99
 100     BOOST_STATIC_ASSERT_MSG(
 101         boost::is_void< typename boost::remove_pointer<From>::type >::value,
 102         "`agressive_ptr_cast` function must be used only for casting to or from void pointers."
 103     );
 104
 105     To res = 0;
 106     std::memcpy(&res, &v, sizeof(From));
 107     return res;
 108 }
 109
 110 template <class To, class From>
 111 BOOST_FORCEINLINE typename boost::disable_if_c<boost::is_member_pointer<To>::value || !boost::is_member_pointer<From>::value, To>::type
 112     aggressive_ptr_cast(From /* v */) BOOST_NOEXCEPT
 113 {
 114     BOOST_STATIC_ASSERT_MSG(
 115         boost::is_pointer<To>::value,
 116         "`agressive_ptr_cast` function must be used only for pointer casting."
 117     );
 118
 119     BOOST_STATIC_ASSERT_MSG(
 120         boost::is_void< typename boost::remove_pointer<To>::type >::value,
 121         "`agressive_ptr_cast` function must be used only for casting to or from void pointers."
 122     );
 123
 124     BOOST_STATIC_ASSERT_MSG(
 125         !sizeof(From),
 126         "Casting from member pointers to void pointer is not implemnted in `agressive_ptr_cast`."
 127     );
 128
 129     return 0;
 130 }
 131
 132 }}} // boost::dll::detail
 133
 134 #endif // BOOST_DLL_DETAIL_AGGRESSIVE_PTR_CAST_HPP
 135