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Fix: prevented the binding illegal temporary to optional<const int&>

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Older MSVC versions add illegal temporary when you want to assign from const integral value.
This commit is contained in:
Andrzej Krzemienski
2016-02-18 23:18:01 +01:00
parent 1671966380
commit 44d57a1d8b
20 changed files with 161 additions and 109 deletions
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28
include/boost/optional/detail/optional_reference_spec.hpp
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@ -12,6 +12,11 @@
#ifndef BOOST_OPTIONAL_DETAIL_OPTIONAL_REFERENCE_SPEC_AJK_03OCT2015_HPP
#define BOOST_OPTIONAL_DETAIL_OPTIONAL_REFERENCE_SPEC_AJK_03OCT2015_HPP
#ifdef BOOST_OPTIONAL_CONFIG_NO_PROPER_ASSIGN_FROM_CONST_INT
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_const.hpp>
#endif
# if 1
namespace boost {
@ -39,6 +44,19 @@ BOOST_DEDUCED_TYPENAME boost::remove_reference<T>::type& forward_reference(T&& r
#endif // BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
template <class From>
void prevent_assignment_from_false_const_integral()
{
#ifndef BOOST_OPTIONAL_CONFIG_ALLOW_BINDING_TO_RVALUES
#ifdef BOOST_OPTIONAL_CONFIG_NO_PROPER_ASSIGN_FROM_CONST_INT
// MSVC compiler without rvalue refernces: we need to disable the asignment from
// const integral lvalue reference, as it may be an invalid temporary
BOOST_STATIC_ASSERT_MSG(!(boost::is_const<From>::value && boost::is_integral<From>::value),
"binding const lvalue references to integral types is disabled in this compiler");
#endif
#endif
}
template <class T>
struct is_optional_
{
@ -140,11 +158,15 @@ public:
template <class U>
optional(bool cond, U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) BOOST_NOEXCEPT : ptr_(cond ? boost::addressof(v) : 0) {}
template <class U>
BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U>, optional<T&>&>::type
operator=(U& v) BOOST_NOEXCEPT { ptr_ = boost::addressof(v); return *this; }
operator=(U& v) BOOST_NOEXCEPT
{
detail::prevent_assignment_from_false_const_integral<U>();
ptr_ = boost::addressof(v); return *this;
}
template <class U>
void emplace(U& v, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<U> >::type* = 0) BOOST_NOEXCEPT
{ ptr_ = boost::addressof(v); }