1// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
2// Copyright (C) 2016 Andrzej Krzemienski.
3//
4// Use, modification, and distribution is subject to the Boost Software
5// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt)
7//
8// See http://www.boost.org/libs/optional for documentation.
9//
10// You are welcome to contact the author at:
11// fernando_cacciola@hotmail.com
12// akrzemi1@gmail.com
13
14#ifndef BOOST_OPTIONAL_OPTIONAL_DETAIL_OPTIONAL_ALIGNED_STORAGE_AJK_12FEB2016_HPP
15#define BOOST_OPTIONAL_OPTIONAL_DETAIL_OPTIONAL_ALIGNED_STORAGE_AJK_12FEB2016_HPP
16
17namespace boost {
18
19namespace optional_detail {
20// This local class is used instead of that in "aligned_storage.hpp"
21// because I've found the 'official' class to ICE BCB5.5
22// when some types are used with optional<>
23// (due to sizeof() passed down as a non-type template parameter)
24template <class T>
25class aligned_storage
26{
27 // Borland ICEs if unnamed unions are used for this!
28 union
29 // This works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
30#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
31 __attribute__((__may_alias__))
32#endif
33 dummy_u
34 {
35 char data[ sizeof(T) ];
36 BOOST_DEDUCED_TYPENAME type_with_alignment<
37 ::boost::alignment_of<T>::value >::type aligner_;
38 } dummy_ ;
39
40 public:
41
42#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
43 void const* address() const { return &dummy_; }
44 void * address() { return &dummy_; }
45#else
46 void const* address() const { return dummy_.data; }
47 void * address() { return dummy_.data; }
48#endif
49
50#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
51 // This workaround is supposed to silence GCC warnings about broken strict aliasing rules
52 T const* ptr_ref() const
53 {
54 union { void const* ap_pvoid; T const* as_ptype; } caster = { address() };
55 return caster.as_ptype;
56 }
57 T * ptr_ref()
58 {
59 union { void* ap_pvoid; T* as_ptype; } caster = { address() };
60 return caster.as_ptype;
61 }
62#else
63 T const* ptr_ref() const { return static_cast<T const*>(address()); }
64 T * ptr_ref() { return static_cast<T *> (address()); }
65#endif
66
67 T const& ref() const { return *ptr_ref(); }
68 T & ref() { return *ptr_ref(); }
69
70} ;
71
72} // namespace optional_detail
73} // namespace boost
74
75#endif // header guard
76