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[libcxx/variant] Implement workaround for GCC bug. 

A parameter pack is deemed to be uncaptured, which is bogus... but it seems to
be because it's within an expression that involves `decltype` of an uncaptured
pack or something: https://godbolt.org/z/b8z3sh

Drive-by fix for uglified name.

Differential Revision: https://reviews.llvm.org/D86827
This commit is contained in:
Michael Park 2020-08-30 12:42:35 -04:00 committed by Louis Dionne
parent 2d3e12818e
commit 7d15ece79c
1 changed files with 20 additions and 20 deletions
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40
libcxx/include/variant
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@ -537,25 +537,32 @@ static constexpr auto __make_vtable(_Fp __f) {
}
struct __base {
template <class _Vis, class... _Vs>
struct __dispatch {
template <size_t... _Is>
inline _LIBCPP_INLINE_VISIBILITY
constexpr auto operator()(integral_constant<size_t, _Is>...) const noexcept {
return +[](_Vis&& __vis, _Vs&&... __vs) -> decltype(auto) {
return __invoke_constexpr(
_VSTD::forward<_Vis>(__vis),
__access::__base::__get_alt<_Is>(_VSTD::forward<_Vs>(__vs))...);
};
}
};
template <class _Vis, class _Vp, class _Wp>
inline _LIBCPP_INLINE_VISIBILITY
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 = [](auto __i) {
return +[](_Vis&& __vis_, _Vp&& __v_, _Wp&& __w_) -> decltype(auto) {
constexpr size_t _Ip = decltype(__i)::value;
return __invoke_constexpr(
_VSTD::forward<_Vis>(__vis_),
__access::__base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v_)),
__access::__base::__get_alt<_Ip>(_VSTD::forward<_Wp>(__w_)));
};
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(integral_constant<size_t, _Ip>{})( \
return __dispatch_at(integral_constant<size_t, _Ip>{})( \
_VSTD::forward<_Vis>(__vis), \
_VSTD::forward<_Vp>(__v), \
_VSTD::forward<_Wp>(__w)); \
@ -569,7 +576,7 @@ struct __base {
default: __throw_bad_variant_access();
}
} else {
constexpr auto __vtable = __make_vtable<__size>(__dispatch);
constexpr auto __vtable = __make_vtable<__size>(__dispatch_at);
return __vtable[__index + 1](_VSTD::forward<_Vis>(__vis),
_VSTD::forward<_Vp>(__v),
_VSTD::forward<_Wp>(__w));
@ -594,14 +601,7 @@ struct __base {
static constexpr decltype(auto)
__visit_alt_impl(index_sequence<_Is...>, _Vis&& __vis, _Vs&&... __vs) {
using __multi = __multi<__uncvref_t<_Vs>::__size()...>;
constexpr auto __dispatch = [](auto... __is) {
return +[](_Vis&& __vis_, _Vs&&... __vs_) -> decltype(auto) {
return __invoke_constexpr(
_VSTD::forward<_Vis>(__vis_),
__access::__base::__get_alt<decltype(__is)::value>(
_VSTD::forward<_Vs>(__vs_))...);
};
};
constexpr __dispatch<_Vis, _Vs...> __dispatch;
#define _LIBCPP_VARIANT_CASE(_Ip) \
case _Ip: { \
if constexpr (_Ip < __multi::__size) { \
@ -874,9 +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) {
auto* result = ::new ((void*)_VSTD::addressof(__a))
auto* __result = ::new ((void*)_VSTD::addressof(__a))
__alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
return result->__value;
return __result->__value;
}
template <class _Rhs>