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Fix #12563

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This commit is contained in:
Andrzej Krzemienski
2016-11-19 14:57:40 +01:00
parent 8d69e99e78
commit 7ea2ca6c40
3 changed files with 50 additions and 7 deletions
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14
include/boost/optional/optional.hpp
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@ -745,6 +745,10 @@ struct is_convertible_to_T_or_factory
, boost::true_type, boost::false_type>::type
{};
template <typename T, typename U>
struct is_optional_constructible : boost::is_constructible<T, U>
{};
#else
#define BOOST_OPTIONAL_DETAIL_NO_IS_CONSTRUCTIBLE_TRAIT
@ -753,6 +757,10 @@ template <typename, typename>
struct is_convertible_to_T_or_factory : boost::true_type
{};
template <typename T, typename U>
struct is_optional_constructible : boost::true_type
{};
#endif // is_convertible condition
template <typename T, typename U>
@ -812,7 +820,8 @@ class optional : public optional_detail::optional_base<T>
// Requires a valid conversion from U to T.
// Can throw if T::T(U const&) does
template<class U>
explicit optional ( optional<U> const& rhs )
explicit optional ( optional<U> const& rhs,
typename boost::enable_if< optional_detail::is_optional_constructible<T, U const&> >::type* = 0)
:
base()
{
@ -825,7 +834,8 @@ class optional : public optional_detail::optional_base<T>
// Requires a valid conversion from U to T.
// Can throw if T::T(U&&) does
template<class U>
explicit optional ( optional<U> && rhs )
explicit optional ( optional<U> && rhs,
typename boost::enable_if< optional_detail::is_optional_constructible<T, U> >::type* = 0 )
:
base()
{