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Fix SFINAE conditions on emplace<U>

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This commit is contained in:
Peter Dimov
2019-02-18 20:40:17 +02:00
parent 8f2ef7ddc1
commit 24fae0f542
1 changed files with 6 additions and 2 deletions
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8
include/boost/variant2/variant.hpp
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@ -1171,16 +1171,20 @@ public:
// modifiers
template<class U, class... A, class I = mp_find<variant<T...>, U>, class E = typename std::enable_if<std::is_constructible<U, A...>::value>::type>
template<class U, class... A,
class E = typename std::enable_if< mp_count<variant<T...>, U>::value == 1 && std::is_constructible<U, A...>::value >::type>
BOOST_CXX14_CONSTEXPR U& emplace( A&&... a )
{
using I = mp_find<variant<T...>, U>;
variant_base::template emplace<I::value>( std::forward<A>(a)... );
return _get_impl( I() );
}
template<class U, class V, class... A, class I = mp_find<variant<T...>, U>, class E = typename std::enable_if<std::is_constructible<U, std::initializer_list<V>&, A...>::value>::type>
template<class U, class V, class... A,
class E = typename std::enable_if< mp_count<variant<T...>, U>::value == 1 && std::is_constructible<U, std::initializer_list<V>&, A...>::value >::type>
BOOST_CXX14_CONSTEXPR U& emplace( std::initializer_list<V> il, A&&... a )
{
using I = mp_find<variant<T...>, U>;
variant_base::template emplace<I::value>( il, std::forward<A>(a)... );
return _get_impl( I() );
}