PR libstdc++/81912 make std::__iterator_category constexpr

	PR libstdc++/81912
	* include/bits/stl_iterator_base_types.h (__iterator_category): Add
	constexpr for C++11 and later.
	* testsuite/24_iterators/container_access.cc: Add target selector.
	* testsuite/24_iterators/range_access.cc: Fix clause number in
	comment.
	* testsuite/24_iterators/range_access_cpp14.cc: Likewise.
	* testsuite/24_iterators/range_access_cpp17.cc: New.

From-SVN: r251234

libstdc++-v3/ChangeLog

+2017-08-21  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/81912
+	* include/bits/stl_iterator_base_types.h (__iterator_category): Add
+	constexpr for C++11 and later.
+	* testsuite/24_iterators/container_access.cc: Add target selector.
+	* testsuite/24_iterators/range_access.cc: Fix clause number in
+	comment.
+	* testsuite/24_iterators/range_access_cpp14.cc: Likewise.
+	* testsuite/24_iterators/range_access_cpp17.cc: New.
+
 2017-08-21  Richard Biener  <rguenther@suse.de>
 
 	* testsuite/libstdc++-prettyprinters/prettyprinters.exp: Run all

libstdc++-v3/include/bits/stl_iterator_base_types.h

@@ -200,7 +200,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  sugar for internal library use only.
   */
   template<typename _Iter>
-    inline typename iterator_traits<_Iter>::iterator_category
+    inline _GLIBCXX_CONSTEXPR
+    typename iterator_traits<_Iter>::iterator_category
     __iterator_category(const _Iter&)
     { return typename iterator_traits<_Iter>::iterator_category(); }
 

libstdc++-v3/testsuite/24_iterators/container_access.cc

-// { dg-do run }
+// { dg-do run { target c++1z } }
 // { dg-options "-std=gnu++17" }
 
 // Copyright (C) 2015-2017 Free Software Foundation, Inc.
@@ -62,7 +62,6 @@ test03()
   static_assert(s == 3);
   constexpr auto e = std::empty(il3);
   static_assert(!e);
-
 }
 
 void

libstdc++-v3/testsuite/24_iterators/range_access.cc

@@ -17,7 +17,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// 24.6.5, range access [iterator.range]
+// C++ 2011 24.6.5, range access [iterator.range]
 
 #include <iterator>
 

libstdc++-v3/testsuite/24_iterators/range_access_cpp14.cc

@@ -17,7 +17,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// 24.6.5, range access [iterator.range]
+// C++ 2014 24.7, range access [iterator.range]
 
 #include <iterator>
 #include <vector>

libstdc++-v3/testsuite/24_iterators/range_access_cpp17.cc

+// { dg-do compile { target c++1z } }
+// { dg-options "-std=gnu++17" }
+
+// 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/>.
+
+// C++ 2017 27.7, range access [iterator.range]
+
+#include <iterator>
+
+void
+test01()
+{
+  using std::reverse_iterator;
+  static int i[1];
+  static_assert(std::cbegin(i) == i);
+  static_assert(std::cend(i) == i+1);
+  static_assert(std::rbegin(i) == reverse_iterator<int*>(i+1));
+  static_assert(std::rend(i) == reverse_iterator<int*>(i));
+  static_assert(std::crbegin(i) == reverse_iterator<int*>(i+1));
+  static_assert(std::crend(i) == reverse_iterator<int*>(i));
+}
+
+void
+test02()
+{
+  static int i[] = { 1, 2 };
+  static_assert(std::distance(std::begin(i), std::end(i)) == 2);
+  static_assert(std::distance(std::cbegin(i), std::cend(i)) == 2);
+}
+
+void
+test03()
+{
+  using std::reverse_iterator;
+  static std::initializer_list<int> il{1};
+  static_assert(std::cbegin(il) == il.begin());
+  static_assert(std::cend(il) == il.end());
+  static_assert(std::rbegin(il) == reverse_iterator<const int*>(il.end()));
+  static_assert(std::rend(il) == reverse_iterator<const int*>(il.begin()));
+  static_assert(std::crbegin(il) == reverse_iterator<const int*>(il.end()));
+  static_assert(std::crend(il) == reverse_iterator<const int*>(il.begin()));
+}