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value_or() requires that U is convertible to T

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Due to Vladimir Batov.
This commit is contained in:
Andrzej Krzemienski
2014-06-14 22:49:37 +02:00
parent 8fc2901fad
commit 31c9119266
9 changed files with 66 additions and 17 deletions
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22
include/boost/optional/optional.hpp
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@ -35,6 +35,7 @@
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/decay.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_lvalue_reference.hpp>
#include <boost/type_traits/is_nothrow_move_assignable.hpp>
#include <boost/type_traits/is_nothrow_move_constructible.hpp>
@ -1060,18 +1061,31 @@ class optional : public optional_detail::optional_base<T>
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
template <class U>
value_type value_or ( U&& v ) const&
{ return this->is_initialized() ? get() : static_cast<value_type>(boost::forward<U>(v)); }
{
BOOST_STATIC_ASSERT(is_convertible<U&&, value_type>::value);
return this->is_initialized() ? get() : static_cast<value_type>(boost::forward<U>(v));
}
template <class U>
value_type value_or ( U&& v ) &&
{ return this->is_initialized() ? boost::move(get()) : static_cast<value_type>(boost::forward<U>(v)); }
{
BOOST_STATIC_ASSERT(is_convertible<U&&, value_type>::value);
return this->is_initialized() ? boost::move(get()) : static_cast<value_type>(boost::forward<U>(v));
}
#elif !defined BOOST_NO_CXX11_RVALUE_REFERENCES
template <class U>
value_type value_or ( U&& v ) const
{ return this->is_initialized() ? get() : static_cast<value_type>(boost::forward<U>(v)); }
{
BOOST_STATIC_ASSERT(is_convertible<U&&, value_type>::value);
return this->is_initialized() ? get() : static_cast<value_type>(boost::forward<U>(v));
}
#else
template <class U>
value_type value_or ( U const& v ) const { return this->is_initialized() ? get() : static_cast<value_type>(v); }
value_type value_or ( U const& v ) const
{
BOOST_STATIC_ASSERT(is_convertible<U const&, value_type>::value);
return this->is_initialized() ? get() : static_cast<value_type>(v);
}
#endif
bool operator!() const BOOST_NOEXCEPT { return !this->is_initialized() ; }