--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill/constrained.cc	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,137 @@
+// 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 run { target c++2a } }
+
+#include <algorithm>
+#include <cstring>
+#include <deque>
+#include <list>
+#include <memory>
+#include <span>
+#include <string>
+#include <vector>
+
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_forward_range;
+
+namespace ranges = std::ranges;
+
+template<typename T>
+void
+test01(const T& value)
+{
+  static_assert(std::equality_comparable<T>);
+
+  for (int k = 0; k < 6; k++)
+    {
+      constexpr int size = 1024;
+      auto buffer = std::unique_ptr<char[]>(new char[sizeof(T)*size]);
+      std::span<T> rx((T *)buffer.get(), size);
+
+      auto i = rx.begin();
+      if (k == 0)
+	i = ranges::uninitialized_fill(rx.begin(), rx.end(), value);
+      else if (k == 1)
+	i = ranges::uninitialized_fill(rx, value);
+      else if (k == 2)
+	i = ranges::uninitialized_fill_n(rx.begin(), 1024, value);
+      else if (k == 3)
+	i = ranges::uninitialized_fill(rx.begin(), rx.end(), value);
+      else if (k == 4)
+	i = ranges::uninitialized_fill(std::as_const(rx), value);
+      else if (k == 5)
+	i = ranges::uninitialized_fill_n(rx.begin(), 1024, value);
+      else
+	__builtin_abort();
+
+      VERIFY( i == rx.end() );
+      VERIFY( ranges::find_if(rx, [&value](const T& v) { return value != v; }) == i );
+
+      ranges::destroy(rx);
+    }
+}
+
+struct X
+{
+  static constexpr int limit = 67;
+  static inline int construct_count = 0;
+  static inline int destruct_count = 0;
+
+  struct exception {};
+
+  bool live = false;
+
+  X(int)
+  {
+    if (construct_count >= limit)
+      throw exception{};
+    construct_count++;
+    live = true;
+  }
+
+  ~X()
+  {
+    VERIFY( live );
+    live = false;
+    destruct_count++;
+  }
+};
+
+template<bool test_sized>
+void
+test02()
+{
+  constexpr int size = 100;
+  auto buffer = std::unique_ptr<char[]>(new char[sizeof(X)*size]);
+  test_forward_range<X> rx((X *)buffer.get(), (X *)buffer.get() + size);
+  int value = 5;
+  try
+    {
+      X::construct_count = 0;
+      X::destruct_count = 0;
+      if constexpr (test_sized)
+	ranges::uninitialized_fill_n(rx.begin(), size, value);
+      else
+	ranges::uninitialized_fill(rx, value);
+      VERIFY( false && "exception not thrown" );
+    }
+  catch (const X::exception&)
+    {
+      VERIFY( X::construct_count == X::limit );
+      VERIFY( X::destruct_count == X::limit );
+    }
+}
+
+int
+main()
+{
+  test01<char>(5);
+  test01<int>(3);
+  test01<long long>(17);
+  test01<float>(2.18);
+  test01<double>(3.98);
+  test01<std::vector<char>>({'a', 'b', 'c', 'd'});
+  test01<std::string>("hello");
+  test01<std::deque<double>>({1.1,2.1,3.1});
+  test01<std::list<std::vector<std::deque<double>>>>({{{3.4},{1}},{{7.9}}});
+
+  test02<false>();
+  test02<true>();
+}