[libcxx-commits] [libcxx] 35d2269 - [libc++] Re-apply the switch-based std::variant implementation
Louis Dionne via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Oct 28 14:09:56 PDT 2020
Author: Michael Park
Date: 2020-10-28T17:09:11-04:00
New Revision: 35d226911165a9aae1f01f521a0019f1a9c0a25f
URL: https://github.com/llvm/llvm-project/commit/35d226911165a9aae1f01f521a0019f1a9c0a25f
DIFF: https://github.com/llvm/llvm-project/commit/35d226911165a9aae1f01f521a0019f1a9c0a25f.diff
LOG: [libc++] Re-apply the switch-based std::variant implementation
This commit is a mass re-application of the following commits:
7d15ece79c16dc3237fc514ff56a69e3d58fbd39
e0ec7a02064968c7df11713689107148b4efb993
02197f7e50b938f8167b17b89bdf7c55feff4339
a175a96517c5d9dc05ba13a6481b1b031a53a22f
Those were temporarily reverted in 057028ed391f8, and never re-applied.
Re-committed by @ldionne (author edited for credit).
Differential Revision: https://reviews.llvm.org/D90168
Added:
Modified:
libcxx/include/variant
Removed:
################################################################################
diff --git a/libcxx/include/variant b/libcxx/include/variant
index e6da096f6c38..a7471f8592d6 100644
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -354,9 +354,9 @@ struct __valueless_t {};
enum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
-template <typename _Tp,
- template <typename> class _IsTriviallyAvailable,
- template <typename> class _IsAvailable>
+template <class _Tp,
+ template <class> class _IsTriviallyAvailable,
+ template <class> class _IsAvailable>
constexpr _Trait __trait =
_IsTriviallyAvailable<_Tp>::value
? _Trait::_TriviallyAvailable
@@ -373,7 +373,7 @@ constexpr _Trait __common_trait(initializer_list<_Trait> __traits) {
return __result;
}
-template <typename... _Types>
+template <class... _Types>
struct __traits {
static constexpr _Trait __copy_constructible_trait =
__common_trait({__trait<_Types,
@@ -434,183 +434,270 @@ struct __variant {
namespace __visitation {
-struct __base {
- template <class _Visitor, class... _Vs>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr decltype(auto)
- __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
- constexpr auto __fdiagonal =
- __make_fdiagonal<_Visitor&&,
- decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
- return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
- _VSTD::forward<_Vs>(__vs).__as_base()...);
- }
+#define _LIBCPP_VARIANT_CASES_4(_Case, _Base) \
+ _Case(_Base + 0) \
+ _Case(_Base + 1) \
+ _Case(_Base + 2) \
+ _Case(_Base + 3)
- template <class _Visitor, class... _Vs>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
- _Vs&&... __vs) {
- constexpr auto __fmatrix =
- __make_fmatrix<_Visitor&&,
- decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
- return __at(__fmatrix, __vs.index()...)(
- _VSTD::forward<_Visitor>(__visitor),
- _VSTD::forward<_Vs>(__vs).__as_base()...);
- }
+#define _LIBCPP_VARIANT_CASES_16(_Case, _Base) \
+ _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 0) \
+ _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 1) \
+ _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 2) \
+ _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 3)
-private:
- template <class _Tp>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
+#define _LIBCPP_VARIANT_CASES_64(_Case, _Base) \
+ _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 0) \
+ _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 1) \
+ _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 2) \
+ _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 3)
+
+#define _LIBCPP_VARIANT_CASES_256(_Case, _Base) \
+ _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 0) \
+ _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 1) \
+ _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 2) \
+ _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 3)
+
+#define _LIBCPP_VARIANT_CASES(_NumCases, _Case) \
+ _LIBCPP_CONCAT(_LIBCPP_VARIANT_CASES_, _NumCases)(_Case, 0)
+
+#define _LIBCPP_VARIANT_SWITCH_MAX 256
- template <class _Tp, size_t _Np, typename... _Indices>
+template <class _Iter, class _Fp, size_t... _Is>
+inline _LIBCPP_INLINE_VISIBILITY
+static constexpr void __fill_cartesian_impl(
+ _Iter __iter, _Fp __f, index_sequence<_Is...>) {
+ *__iter = __f(integral_constant<size_t, _Is>{}...);
+}
+
+template <class _Iter, class _Fp, size_t... _Is, size_t... _Js, class... _Ls>
+inline _LIBCPP_INLINE_VISIBILITY
+static constexpr void __fill_cartesian_impl(
+ _Iter __iter, _Fp __f, index_sequence<_Is...>, index_sequence<_Js...>, _Ls... __ls) {
+ constexpr size_t _Mp = (1 * ... * _Ls::size());
+ (__fill_cartesian_impl(
+ __iter + _Js * _Mp, __f, index_sequence<_Is..., _Js>{}, __ls...), ...);
+}
+
+template <size_t... _Ns, class _Iter, class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+static constexpr void __fill_cartesian(_Iter __iter, _Fp __f) {
+ __fill_cartesian_impl(
+ __iter, __f, index_sequence<>{}, make_index_sequence<_Ns>{}...);
+}
+
+template <size_t _Np, size_t... _Ns>
+struct __multi {
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
- size_t __index, _Indices... __indices) {
- return __at(__elems[__index], __indices...);
- }
+ static constexpr size_t __size = (_Np * ... * _Ns);
- template <class _Fp, class... _Fs>
- static constexpr void __std_visit_visitor_return_type_check() {
- static_assert(
- __all<is_same_v<_Fp, _Fs>...>::value,
- "`std::visit` requires the visitor to have a single return type.");
+ inline _LIBCPP_INLINE_VISIBILITY
+ static constexpr size_t
+ __index(const size_t (&__is)[sizeof...(_Ns) + 1]) noexcept {
+ constexpr size_t __ns[] = {_Ns..., 1};
+ size_t __result = 0;
+ for (size_t __i = 0; __i < sizeof...(_Ns) + 1; ++__i) {
+ if (__is[__i] == variant_npos) {
+ return variant_npos;
+ }
+ __result += __is[__i];
+ __result *= __ns[__i];
+ }
+ return __result;
}
+};
- template <class... _Fs>
+template <size_t... _Ns>
+struct __indices {
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_farray(_Fs&&... __fs) {
- __std_visit_visitor_return_type_check<__uncvref_t<_Fs>...>();
- using __result = array<common_type_t<__uncvref_t<_Fs>...>, sizeof...(_Fs)>;
- return __result{{_VSTD::forward<_Fs>(__fs)...}};
- }
+ static constexpr auto __value = [] {
+ using _Tp = array<size_t, sizeof...(_Ns)>;
+ array<_Tp, (1 * ... * _Ns)> __result = {};
+ __fill_cartesian<_Ns...>(__result.begin(),
+ [](auto... __is) -> _Tp { return {__is...}; });
+ return __result;
+ }();
+};
- template <std::size_t... _Is>
- struct __dispatcher {
- template <class _Fp, class... _Vs>
+template <size_t... _Ns, class _Fp, class _Rp, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+static constexpr auto __make_vtable_impl(_Fp __f, _Rp (*)(_Args...)) {
+ array<_Rp (*)(_Args...), (1 * ... * _Ns) + 1> __result = {
+ [](_Args...) -> _Rp { __throw_bad_variant_access(); }
+ };
+ __fill_cartesian<_Ns...>(__result.begin() + 1, __f);
+ return __result;
+}
+
+template <size_t... _Ns, class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+static constexpr auto __make_vtable(_Fp __f) {
+ using _Tp = decltype(__f(integral_constant<size_t, (_Ns, 0)>{}...));
+ return __make_vtable_impl<_Ns...>(__f, _Tp{});
+}
+
+struct __base {
+ template <class _Vis, class... _Vs>
+ struct __dispatch {
+ template <size_t... _Is>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
+ constexpr auto operator()(integral_constant<size_t, _Is>...) const noexcept {
+ return +[](_Vis&& __vis, _Vs&&... __vs) -> decltype(auto) {
return __invoke_constexpr(
- static_cast<_Fp>(__f),
- __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
+ _VSTD::forward<_Vis>(__vis),
+ __access::__base::__get_alt<_Is>(_VSTD::forward<_Vs>(__vs))...);
+ };
}
};
- template <class _Fp, class... _Vs, size_t... _Is>
+ template <class _Vis, class _Vp, class _Wp>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_dispatch(index_sequence<_Is...>) {
- return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
- }
-
- template <size_t _Ip, class _Fp, class... _Vs>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fdiagonal_impl() {
- return __make_dispatch<_Fp, _Vs...>(
- index_sequence<(__identity<_Vs>{}, _Ip)...>{});
- }
-
- template <class _Fp, class... _Vs, size_t... _Is>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
- return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
+ static constexpr decltype(auto)
+ __visit_alt_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) {
+ constexpr size_t __size = __uncvref_t<_Vp>::__size();
+ static_assert(__size == __uncvref_t<_Wp>::__size());
+ constexpr auto __dispatch_at = [](auto __i) {
+ return __dispatch<_Vis, _Vp, _Wp>{}(__i, __i);
+ };
+#define _LIBCPP_VARIANT_CASE(_Ip) \
+ case _Ip: { \
+ if constexpr (_Ip < __size) { \
+ return __dispatch_at(integral_constant<size_t, _Ip>{})( \
+ _VSTD::forward<_Vis>(__vis), \
+ _VSTD::forward<_Vp>(__v), \
+ _VSTD::forward<_Wp>(__w)); \
+ } else { \
+ _LIBCPP_UNREACHABLE(); \
+ } \
}
-
- template <class _Fp, class _Vp, class... _Vs>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fdiagonal() {
- constexpr size_t _Np = __uncvref_t<_Vp>::__size();
- static_assert(__all<(_Np == __uncvref_t<_Vs>::__size())...>::value);
- return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
+ if constexpr (__size <= _LIBCPP_VARIANT_SWITCH_MAX) {
+ switch (__index) {
+ _LIBCPP_VARIANT_CASES(_LIBCPP_VARIANT_SWITCH_MAX, _LIBCPP_VARIANT_CASE)
+ default: __throw_bad_variant_access();
+ }
+ } else {
+ constexpr auto __vtable = __make_vtable<__size>(__dispatch_at);
+ return __vtable[__index + 1](_VSTD::forward<_Vis>(__vis),
+ _VSTD::forward<_Vp>(__v),
+ _VSTD::forward<_Wp>(__w));
+ }
+#undef _LIBCPP_VARIANT_CASE
}
- template <class _Fp, class... _Vs, size_t... _Is>
+ template <size_t... _Is, class _Vis, class... _Vs>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
- return __make_dispatch<_Fp, _Vs...>(__is);
+ static constexpr decltype(auto) __visit_alt(_Vis&& __vis, _Vs&&... __vs) {
+ if constexpr (sizeof...(_Vs) == 0) {
+ return __invoke_constexpr(_VSTD::forward<_Vis>(__vis));
+ } else {
+ return __visit_alt_impl(index_sequence_for<_Vs...>{},
+ _VSTD::forward<_Vis>(__vis),
+ _VSTD::forward<_Vs>(__vs)...);
+ }
}
- template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
+ template <size_t... _Is, class _Vis, class... _Vs>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
- index_sequence<_Js...>,
- _Ls... __ls) {
- return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
- index_sequence<_Is..., _Js>{}, __ls...)...);
+ static constexpr decltype(auto)
+ __visit_alt_impl(index_sequence<_Is...>, _Vis&& __vis, _Vs&&... __vs) {
+ using __multi = __multi<__uncvref_t<_Vs>::__size()...>;
+ constexpr __dispatch<_Vis, _Vs...> __dispatch;
+#define _LIBCPP_VARIANT_CASE(_Ip) \
+ case _Ip: { \
+ if constexpr (_Ip < __multi::__size) { \
+ return __dispatch(integral_constant<size_t, __itable[_Ip][_Is]>{}...)( \
+ _VSTD::forward<_Vis>(__vis), _VSTD::forward<_Vs>(__vs)...); \
+ } else { \
+ _LIBCPP_UNREACHABLE(); \
+ } \
}
-
- template <class _Fp, class... _Vs>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_fmatrix() {
- return __make_fmatrix_impl<_Fp, _Vs...>(
- index_sequence<>{}, make_index_sequence<__uncvref_t<_Vs>::__size()>{}...);
+ if constexpr (__multi::__size <= _LIBCPP_VARIANT_SWITCH_MAX) {
+ constexpr const auto& __itable =
+ __indices<__uncvref_t<_Vs>::__size()...>::__value;
+ switch (__multi::__index({__vs.index()...})) {
+ _LIBCPP_VARIANT_CASES(_LIBCPP_VARIANT_SWITCH_MAX, _LIBCPP_VARIANT_CASE)
+ default: __throw_bad_variant_access();
+ }
+ } else {
+ constexpr auto __vtable =
+ __make_vtable<__uncvref_t<_Vs>::__size()...>(__dispatch);
+ return __vtable[__multi::__index({__vs.index()...}) + 1](
+ _VSTD::forward<_Vis>(__vis), _VSTD::forward<_Vs>(__vs)...);
+ }
+#undef _LIBCPP_VARIANT_CASE
}
};
struct __variant {
- template <class _Visitor, class... _Vs>
+ template <class _Vis, class _Vp, class _Wp>
inline _LIBCPP_INLINE_VISIBILITY
static constexpr decltype(auto)
- __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
+ __visit_alt_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) {
return __base::__visit_alt_at(__index,
- _VSTD::forward<_Visitor>(__visitor),
- _VSTD::forward<_Vs>(__vs).__impl...);
+ _VSTD::forward<_Vis>(__vis),
+ _VSTD::forward<_Vp>(__v).__impl,
+ _VSTD::forward<_Wp>(__w).__impl);
}
- template <class _Visitor, class... _Vs>
+ template <class _Vis, class... _Vs>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
- _Vs&&... __vs) {
- return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor),
+ static constexpr decltype(auto) __visit_alt(_Vis&& __vis, _Vs&&... __vs) {
+ return __base::__visit_alt(_VSTD::forward<_Vis>(__vis),
_VSTD::forward<_Vs>(__vs).__impl...);
}
- template <class _Visitor, class... _Vs>
+ template <class _Vis, class _Vp, class _Wp>
inline _LIBCPP_INLINE_VISIBILITY
static constexpr decltype(auto)
- __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
- return __visit_alt_at(
- __index,
- __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
- _VSTD::forward<_Vs>(__vs)...);
+ __visit_value_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) {
+ return __visit_alt_at(__index,
+ __make_value_visitor(_VSTD::forward<_Vis>(__vis)),
+ _VSTD::forward<_Vp>(__v),
+ _VSTD::forward<_Wp>(__w));
}
- template <class _Visitor, class... _Vs>
+ template <class _Vis, class... _Vs>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
- _Vs&&... __vs) {
- return __visit_alt(
- __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
- _VSTD::forward<_Vs>(__vs)...);
+ static constexpr decltype(auto) __visit_value(_Vis&& __vis, _Vs&&... __vs) {
+ return __visit_alt(__make_value_visitor(_VSTD::forward<_Vis>(__vis)),
+ _VSTD::forward<_Vs>(__vs)...);
}
private:
- template <class _Visitor, class... _Values>
+ template <class _Vis, class... _Values>
+ inline _LIBCPP_INLINE_VISIBILITY
static constexpr void __std_visit_exhaustive_visitor_check() {
- static_assert(is_invocable_v<_Visitor, _Values...>,
+ static_assert(is_invocable_v<_Vis, _Values...>,
"`std::visit` requires the visitor to be exhaustive.");
}
- template <class _Visitor>
+ template <class _Vis>
struct __value_visitor {
template <class... _Alts>
inline _LIBCPP_INLINE_VISIBILITY
constexpr decltype(auto) operator()(_Alts&&... __alts) const {
__std_visit_exhaustive_visitor_check<
- _Visitor,
- decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
- return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
+ _Vis, decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
+ return __invoke_constexpr(_VSTD::forward<_Vis>(__vis),
_VSTD::forward<_Alts>(__alts).__value...);
}
- _Visitor&& __visitor;
+ _Vis&& __vis;
};
- template <class _Visitor>
+ template <class _Vis>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
- return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
+ static constexpr auto __make_value_visitor(_Vis&& __vis) {
+ return __value_visitor<_Vis>{_VSTD::forward<_Vis>(__vis)};
}
};
+#undef _LIBCPP_VARIANT_SWITCH_MAX
+#undef _LIBCPP_VARIANT_CASES
+#undef _LIBCPP_VARIANT_CASES_256
+#undef _LIBCPP_VARIANT_CASES_64
+#undef _LIBCPP_VARIANT_CASES_16
+#undef _LIBCPP_VARIANT_CASES_4
+
} // namespace __visitation
template <size_t _Index, class _Tp>
@@ -633,7 +720,7 @@ union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \
template <size_t _Index, class _Tp, class... _Types> \
- union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \
+ union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \
_Index, \
_Tp, \
_Types...> { \
@@ -787,9 +874,9 @@ protected:
template <size_t _Ip, class _Tp, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
- ::new ((void*)_VSTD::addressof(__a))
+ auto* __result = ::new ((void*)_VSTD::addressof(__a))
__alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
- return __a.__value;
+ return __result->__value;
}
template <class _Rhs>
@@ -856,7 +943,7 @@ class _LIBCPP_TEMPLATE_VIS __copy_constructor;
#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \
copy_constructor) \
template <class... _Types> \
- class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \
+ class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \
copy_constructible_trait> \
: public __move_constructor<__traits<_Types...>> { \
using __base_type = __move_constructor<__traits<_Types...>>; \
@@ -902,7 +989,7 @@ public:
auto& __emplace(_Args&&... __args) {
this->__destroy();
auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
- _VSTD::forward<_Args>(__args)...);
+ _VSTD::forward<_Args>(__args)...);
this->__index = _Ip;
return __res;
}
@@ -955,7 +1042,7 @@ class _LIBCPP_TEMPLATE_VIS __move_assignment;
#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \
move_assignment) \
template <class... _Types> \
- class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \
+ class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \
move_assignable_trait> \
: public __assignment<__traits<_Types...>> { \
using __base_type = __assignment<__traits<_Types...>>; \
@@ -996,7 +1083,7 @@ class _LIBCPP_TEMPLATE_VIS __copy_assignment;
#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \
copy_assignment) \
template <class... _Types> \
- class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \
+ class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \
copy_assignable_trait> \
: public __move_assignment<__traits<_Types...>> { \
using __base_type = __move_assignment<__traits<_Types...>>; \
@@ -1590,18 +1677,12 @@ constexpr bool operator>=(const variant<_Types...>& __lhs,
__lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs);
}
-template <class _Visitor, class... _Vs>
+template <class _Vis, class... _Vs>
inline _LIBCPP_INLINE_VISIBILITY
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
+constexpr decltype(auto) visit(_Vis&& __vis, _Vs&&... __vs) {
using __variant_detail::__visitation::__variant;
- bool __results[] = {__vs.valueless_by_exception()...};
- for (bool __result : __results) {
- if (__result) {
- __throw_bad_variant_access();
- }
- }
- return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
+ return __variant::__visit_value(_VSTD::forward<_Vis>(__vis),
_VSTD::forward<_Vs>(__vs)...);
}
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