This fixes PR libstdc++/80737.
I actually can't come up with a minimal test case, because I suspect
that there is a front-end bug in GCC. See discussions in the bug.
Tested on x86_64-linux-gnu.
Thanks!
--
Regards,
Tim Shen
commit 6f362991f025069328c4901d95b657d498aad250
Author: Tim Shen <tims...@google.com>
Date: Fri May 19 22:26:58 2017 -0700
2017-05-20 Tim Shen <tims...@google.com>
PR libstdc++/80737
* include/std/variant(variant::variant): SFINAE on is_same first.
* testsuite/20_util/variant/any.cc: test case.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index 0e04a820d69..b9824a5182c 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -936,9 +936,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
noexcept((is_nothrow_move_constructible_v<_Types> && ...)) = default;
template<typename _Tp,
+ typename = enable_if_t<!is_same_v<decay_t<_Tp>, variant>>,
typename = enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
- && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>
- && !is_same_v<decay_t<_Tp>, variant>>>
+ && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>>>
constexpr
variant(_Tp&& __t)
noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>)
diff --git a/libstdc++-v3/testsuite/20_util/variant/any.cc b/libstdc++-v3/testsuite/20_util/variant/any.cc
new file mode 100644
index 00000000000..5811d0f055e
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/variant/any.cc
@@ -0,0 +1,31 @@
+// { dg-options "-std=gnu++17" }
+// { dg-do compile }
+
+// Copyright (C) 2017 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/>.
+
+#include <any>
+#include <variant>
+
+struct A { std::variant<std::any> a; };
+
+void Bar(const A&);
+
+void Foo() {
+ A a;
+ Bar(a);
+}
