--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libstdc++-v3/testsuite/25_algorithms/equal/94013.cc	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,69 @@
+// 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-do run }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  volatile int i[] = { 0, 1, 2, 3 };
+  volatile int j[] = { 1, 2, 3 };
+  int k[] = { 2, 3, 4 };
+
+  VERIFY( std::equal(i+1, i+4, j) );	  // volatile, volatile
+  VERIFY( std::equal(i+2, i+4, k) );	  // volatile, unqual
+  VERIFY( ! std::equal(k, k+3, i+1) );	  // unqual, volatile
+
+  const volatile int* cj = j;
+  VERIFY( ! std::equal(cj, cj+2, cj+1) ); // const volatile, const volatile
+  VERIFY( std::equal(cj, cj+3, i+1) );	  // const volatile, volatile
+  VERIFY( ! std::equal(i, i+2, cj) );	  // volatile, const volatile
+  VERIFY( std::equal(cj+1, cj+3, k) );	  // const volatile, unqual
+  VERIFY( ! std::equal(k, k+2, cj) );	  // unqual, const volatile
+  const int* ck = k;
+  VERIFY( std::equal(ck, ck+2, i+2) );	  // const, volatile
+  VERIFY( ! std::equal(i, i+3, ck) );	  // volatile, const
+  VERIFY( std::equal(cj+1, cj+3, ck) );	  // const volatile, const
+  VERIFY( ! std::equal(ck, ck+1, cj) );	  // const, const volatile
+
+#if __cplusplus > 201703L
+  using std::ranges::equal;
+  VERIFY( equal(i+1, i+4, j, j+3) );	  // volatile, volatile
+  VERIFY( equal(i+2, i+4, k, k+2) );	  // volatile, unqual
+  VERIFY( ! equal(k, k+3, i+1, i+4) );	  // unqual, volatile
+
+  VERIFY( ! equal(cj, cj+2, cj+1, cj+3) );// const volatile, const volatile
+  VERIFY( equal(cj, cj+3, i+1, i+4) );	  // const volatile, volatile
+  VERIFY( ! equal(i, i+2, cj, cj+2) );	  // volatile, const volatile
+  VERIFY( equal(cj+1, cj+3, k, k+2) );	  // const volatile, unqual
+  VERIFY( ! equal(k, k+2, cj, cj+2) );	  // unqual, const volatile
+
+  VERIFY( equal(ck, ck+2, i+2, i+4) );	  // const, volatile
+  VERIFY( ! equal(i, i+3, ck, ck+3) );	  // volatile, const
+  VERIFY( equal(cj+1, cj+3, ck, ck+2) );  // const volatile, const
+  VERIFY( ! equal(ck, ck+1, cj, cj+1) );  // const, const volatile
+#endif
+}
+
+int
+main()
+{
+  test01();
+}