PR libstdc++/90008 remove unused capture from variant rel ops

	PR libstdc++/90008
	* include/std/variant (_VARIANT_RELATION_FUNCTION_TEMPLATE): Remove
	unused capture.
	* testsuite/20_util/variant/90008.cc: New test.

From-SVN: r270236

libstdc++-v3/ChangeLog

+2019-04-09  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/90008
+	* include/std/variant (_VARIANT_RELATION_FUNCTION_TEMPLATE): Remove
+	unused capture.
+	* testsuite/20_util/variant/90008.cc: New test.
+
 2019-04-09  Thomas Rodgers  <trodgers@redhat.com>
 
 	* include/pstl/algorithm_impl.h: Add namespace qualification.

libstdc++-v3/include/std/variant

@@ -1160,7 +1160,7 @@ namespace __variant
     { \
       bool __ret = true; \
       __do_visit<__detail::__variant::__visit_with_index>( \
-        [&__ret, &__lhs, __rhs] \
+        [&__ret, &__lhs] \
 		 (auto&& __rhs_mem, auto __rhs_index) mutable \
 		   -> __detail::__variant::__variant_idx_cookie \
         { \

libstdc++-v3/testsuite/20_util/variant/90008.cc

+// Copyright (C) 2019 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>
+
+struct NoCopy
+{
+  NoCopy();
+  NoCopy(const NoCopy&) = delete;
+};
+
+bool operator==(const NoCopy&, const NoCopy&);
+
+using V = std::variant<NoCopy, int>;
+
+bool
+test01(const V& lhs, const V& rhs)
+{
+  return lhs == rhs;
+}