Remove `std::random_shuffle` in C++17

[mclow.lists]

Summary

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4190 removed random_shuffle from C++1z. (and other stuff)

Wrap all the random_shuffle bits in an #ifdef so they disappear when compiling with -std=c++1z or later.

Introduce a new configuration option, _LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE which allows user code to continue using random_shuffle in C++1z mode if desired.

Add a test for _LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE, and mark all the rest of the random_shuffle tests to XFAIL for c++1z

[EricWF]

LGTM after fixing inline comments.

include/algorithm

3029

We should still expose these when building the library using || defined(_LIBCPP_BUILDING_LIBRARY).

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle.pass.cpp

11

REQUIRES-ANY got removed. This should be written:

// REQUIRES: c++98 || c++03 || c++11 || c++14

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle_rand.pass.cpp

11

REQUIRES-ANY got removed. This should be written:

// REQUIRES: c++98 || c++03 || c++11 || c++14

[EricWF]

@mclow.lists A couple of additional things:

• Add _LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE to the _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES list in __config.
• Add a test for that in test/libcxx/depr/enable_removed_cpp17_features.pass.cpp

include/algorithm

3029

This is specifically needed in this case because the definitions for symbols exist in the dylib and must be declared when compiling it.

[mclow.lists]

Committed as revision 298597

include/algorithm

 
 template <class RandomAccessIterator>
     void
-    random_shuffle(RandomAccessIterator first, RandomAccessIterator last); // deprecated in C++14
+    random_shuffle(RandomAccessIterator first, RandomAccessIterator last); // deprecated in C++14, removed in C++17
 
 template <class RandomAccessIterator, class RandomNumberGenerator>
     void
     random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
-                   RandomNumberGenerator& rand);  // deprecated in C++14
+                   RandomNumberGenerator& rand);  // deprecated in C++14, removed in C++17
 
 template<class PopulationIterator, class SampleIterator,
          class Distance, class UniformRandomBitGenerator>

     return static_cast<result_type>(__u + __p.a());
 }
 
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE)
 class _LIBCPP_TYPE_VIS __rs_default;
 
 _LIBCPP_FUNC_VIS __rs_default __rs_get();

         }
     }
 }
+#endif
 
 template <class _PopulationIterator, class _SampleIterator, class _Distance,
           class _UniformRandomNumberGenerator>

test/libcxx/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle.cxx1z.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// template <class RandomAccessIterator>
+//     void
+//     random_shuffle(RandomAccessIterator first, RandomAccessIterator last);
+// 
+// template <class RandomAccessIterator, class RandomNumberGenerator>
+//     void
+//     random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
+//                    RandomNumberGenerator& rand);
+
+//
+//  In C++17, random_shuffle has been removed.
+//  However, for backwards compatibility, if _LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE
+//  is defined before including <algorithm>, then random_shuffle will be restored.
+
+#define _LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE
+
+#include <algorithm>
+#include <vector>
+
+struct gen
+{
+    std::ptrdiff_t operator()(std::ptrdiff_t n)
+    {
+        return n-1;
+    }
+};
+
+
+int main()
+{
+    std::vector<int> v;
+    std::random_shuffle(v.begin(), v.end());
+    gen r;
+    std::random_shuffle(v.begin(), v.end(), r);
+}

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle.pass.cpp

 //===----------------------------------------------------------------------===//
 
 // <algorithm>
+// REQUIRES-ANY: c++98, c++03, c++11, c++14
 
 // template<RandomAccessIterator Iter>
 //   requires ShuffleIterator<Iter>

test/std/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle_rand.pass.cpp

 //===----------------------------------------------------------------------===//
 
 // <algorithm>
+// REQUIRES-ANY: c++98, c++03, c++11, c++14
 
 // template<RandomAccessIterator Iter, Callable<auto, Iter::difference_type> Rand>
 //   requires ShuffleIterator<Iter>