Simple, short, and sweet, just a thinko.
2018-10-16 Ville Voutilainen <ville.voutilai...@gmail.com>
PR libstdc++/87619
* include/std/variant (__select_index): Fix an off-by-one.
* testsuite/20_util/variant/87619.cc: New.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index 2d86a70..55b6440 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -362,7 +362,7 @@ namespace __variant
template <typename... _Types>
using __select_index =
- typename __select_int::_Select_int_base<sizeof...(_Types) + 1,
+ typename __select_int::_Select_int_base<sizeof...(_Types),
unsigned char,
unsigned short>::type::value_type;
diff --git a/libstdc++-v3/testsuite/20_util/variant/87619.cc b/libstdc++-v3/testsuite/20_util/variant/87619.cc
new file mode 100644
index 0000000..a8db6b8
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/variant/87619.cc
@@ -0,0 +1,46 @@
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++17 } }
+
+#include <variant>
+#include <utility>
+
+
+template<std::size_t I>
+struct S {
+};
+
+template <std::size_t... Is>
+void f_impl(std::index_sequence<Is...>)
+{
+ using V = std::variant<S<Is>...>;
+ static_assert(sizeof(V) == 2);
+}
+
+template <std::size_t I>
+void f()
+{
+ f_impl(std::make_index_sequence<I>{});
+}
+
+int main()
+{
+ f<254>();
+ f<255>();
+}
