--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/92878_92947.cc	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,78 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+// 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/>.
+
+#include <unordered_set>
+#include <testsuite_hooks.h>
+
+struct aggressive_aggregate
+{
+    int a;
+    int b;
+};
+
+bool operator==(const aggressive_aggregate& a,
+	       const aggressive_aggregate& b)
+{
+  return a.a == b.a;
+};
+
+namespace std {
+  template<> struct hash<aggressive_aggregate> {
+    size_t operator()(const aggressive_aggregate& x) const {
+      return std::hash<int>()(x.a);
+    }
+  };
+}
+
+void test_emplace()
+{
+  std::unordered_set<aggressive_aggregate> x;
+  auto emplaced = x.emplace(1, 2);
+  VERIFY(emplaced.first->a == 1);
+  VERIFY(emplaced.first->b == 2);
+  emplaced = x.emplace(2);
+  VERIFY(emplaced.first->a == 2);
+  VERIFY(emplaced.first->b == 0);
+  emplaced = x.emplace();
+  VERIFY(emplaced.first->a == 0);
+  VERIFY(emplaced.first->b == 0);
+}
+
+void test_emplace_hint()
+{
+  std::unordered_set<aggressive_aggregate> x;
+  auto it = x.emplace_hint(x.begin(),
+		      3, 2);
+  VERIFY(it->a == 3);
+  VERIFY(it->b == 2);
+  it = x.emplace_hint(x.begin(),
+		      4);
+  VERIFY(it->a == 4);
+  VERIFY(it->b == 0);
+  it = x.emplace_hint(x.begin());
+  VERIFY(it->a == 0);
+  VERIFY(it->b == 0);
+}
+
+int main()
+{
+  test_emplace();
+  test_emplace_hint();
+}