From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 14 Oct 2021 19:37:38 +0000 (+0100)
Subject: libstdc++: Simplify variant access functions
X-Git-Tag: basepoints/gcc-13~3894
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f87d4c5aec9a1eaca7be61e5c8aab4d6e61b1d8;p=thirdparty%2Fgcc.git

libstdc++: Simplify variant access functions

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.
---

diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index 6377b6731ea4..b85a89d0b7bd 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -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