Add tests for LWG#2299. While doing so, I noticed that the tests we have for the transparent comparators don't actually call them. Fix those tests, too. Now one of them is failing, due to a missing const in <map>. Add that (twice). Next step is to do the same for <unordered_map>

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@241091 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/associative/multimap/multimap.ops/equal_range2.fail.cpp

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <map>
+
+// class multimap
+
+//       iterator find(const key_type& k);
+// const_iterator find(const key_type& k) const;
+// 
+//   The member function templates find, count, lower_bound, upper_bound, and 
+// equal_range shall not participate in overload resolution unless the 
+// qualified-id Compare::is_transparent is valid and denotes a type
+
+
+#include <map>
+#include <cassert>
+
+#include "is_transparent.h"
+
+#if _LIBCPP_STD_VER <= 11
+#error "This test requires is C++14 (or later)"
+#else
+
+int main()
+{
+    {
+    typedef std::multimap<int, double, transparent_less_private> M;
+
+    M().equal_range(C2Int{5});
+    }
+}
+#endif