template<typename _Range>
explicit join_view(_Range&&) -> join_view<views::all_t<_Range>>;
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 3474. Nesting join_views is broken because of CTAD
+ template<typename _View>
+ explicit join_view(join_view<_View>) -> join_view<join_view<_View>>;
+
namespace views
{
inline constexpr __adaptor::_RangeAdaptorClosure join
--- /dev/null
+// Copyright (C) 2020 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++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <ranges>
+#include <vector>
+
+void
+test01()
+{
+ // LWG 3474. Nesting join_views is broken because of CTAD
+ std::vector<std::vector<std::vector<int>>> nested_vectors = {
+ {{1, 2, 3}, {4, 5}, {6}},
+ {{7}, {8, 9}, {10, 11, 12}},
+ {{13}}
+ };
+ auto joined = nested_vectors | std::views::join | std::views::join;
+
+ using V = decltype(joined);
+ static_assert( std::same_as<std::ranges::range_value_t<V>, int> );
+}