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libstdc++: Simplify variant access functions

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libstdc++-v3/ChangeLog:

	* include/std/variant (__variant::__get(in_place_index_t<N>, U&&)):
	Rename to __get_n and remove first argument. Replace pair of
	overloads with a single function using 'if constexpr'.
	(__variant::__get(Variant&&)): Adjust to use __get_n.
This commit is contained in:
Jonathan Wakely 2021-10-14 20:37:38 +01:00
parent 373acac1c8
commit 4f87d4c5ae
1 changed files with 11 additions and 12 deletions
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23
libstdc++-v3/include/std/variant
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@ -279,27 +279,26 @@ namespace __variant
__gnu_cxx::__aligned_membuf<_Type> _M_storage;
};
template<typename _Union>
constexpr decltype(auto)
__get(in_place_index_t<0>, _Union&& __u) noexcept
{ return std::forward<_Union>(__u)._M_first._M_get(); }
template<size_t _Np, typename _Union>
constexpr decltype(auto)
__get(in_place_index_t<_Np>, _Union&& __u) noexcept
__get_n(_Union&& __u) noexcept
{
return __variant::__get(in_place_index<_Np-1>,
std::forward<_Union>(__u)._M_rest);
if constexpr (_Np == 0)
return std::forward<_Union>(__u)._M_first._M_get();
else if constexpr (_Np == 1)
return std::forward<_Union>(__u)._M_rest._M_first._M_get();
else if constexpr (_Np == 2)
return std::forward<_Union>(__u)._M_rest._M_rest._M_first._M_get();
else
return __variant::__get_n<_Np - 3>(
std::forward<_Union>(__u)._M_rest._M_rest._M_rest);
}
// Returns the typed storage for __v.
template<size_t _Np, typename _Variant>
constexpr decltype(auto)
__get(_Variant&& __v) noexcept
{
return __variant::__get(std::in_place_index<_Np>,
std::forward<_Variant>(__v)._M_u);
}
{ return __variant::__get_n<_Np>(std::forward<_Variant>(__v)._M_u); }
template<typename... _Types>
struct _Traits