diff options
| author | Eric Fiselier <eric@efcs.ca> | 2017-04-15 19:32:02 +0000 |
|---|---|---|
| committer | Eric Fiselier <eric@efcs.ca> | 2017-04-15 19:32:02 +0000 |
| commit | 98d9a858da5c08085eeec92f7edabd2555225ef2 (patch) | |
| tree | a749718c034e8d310132129bf81a854d539c50c1 /include | |
| parent | 6ad335bfc0e0aa07d25575d915897fa95cf7f974 (diff) | |
Implement LWG 2857 for variant. Tests from Casey Carter @ Microsoft.
Also mark LWG 2857 as complete, since the changes to optional and
any were completed by Marshall earlier.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@300403 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include')
| -rw-r--r-- | include/variant | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/include/variant b/include/variant index 33f88e057..88f7b240d 100644 --- a/include/variant +++ b/include/variant @@ -53,16 +53,16 @@ namespace std { // 20.7.2.4, modifiers template <class T, class... Args> - void emplace(Args&&...); + T& emplace(Args&&...); template <class T, class U, class... Args> - void emplace(initializer_list<U>, Args&&...); + T& emplace(initializer_list<U>, Args&&...); template <size_t I, class... Args> - void emplace(Args&&...); + variant_alternative_t<I, variant>& emplace(Args&&...); template <size_t I, class U, class... Args> - void emplace(initializer_list<U>, Args&&...); + variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...); // 20.7.2.5, value status constexpr bool valueless_by_exception() const noexcept; @@ -764,9 +764,10 @@ public: protected: template <size_t _Ip, class _Tp, class... _Args> inline _LIBCPP_INLINE_VISIBILITY - static void __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { - ::new (_VSTD::addressof(__a)) + static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { + ::new ((void*)_VSTD::addressof(__a)) __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); + return __a.__value; } template <class _Rhs> @@ -876,11 +877,12 @@ public: template <size_t _Ip, class... _Args> inline _LIBCPP_INLINE_VISIBILITY - void __emplace(_Args&&... __args) { + auto& __emplace(_Args&&... __args) { this->__destroy(); - this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), + auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), _VSTD::forward<_Args>(__args)...); this->__index = _Ip; + return __res; } protected: @@ -1218,8 +1220,8 @@ public: class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> inline _LIBCPP_INLINE_VISIBILITY - void emplace(_Args&&... __args) { - __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); + _Tp& emplace(_Args&&... __args) { + return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); } template < @@ -1231,8 +1233,8 @@ public: enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> inline _LIBCPP_INLINE_VISIBILITY - void emplace(initializer_list<_Up> __il, _Args&&... __args) { - __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); + _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { + return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); } template < @@ -1242,8 +1244,8 @@ public: __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> inline _LIBCPP_INLINE_VISIBILITY - void emplace(_Args&&... __args) { - __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); + _Tp& emplace(_Args&&... __args) { + return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); } template < @@ -1255,8 +1257,8 @@ public: enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> inline _LIBCPP_INLINE_VISIBILITY - void emplace(initializer_list<_Up> __il, _Args&&... __args) { - __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); + _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { + return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); } inline _LIBCPP_INLINE_VISIBILITY |