Implement constexpr support for reverse_iterator. Reviewed as https://reviews.llvm.org/D25534

llvm-svn: 284602

23 files changed, 366 insertions, 23 deletions

diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/default.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/default.pass.cpp
index 72a767d1711..855dbd7ba31 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/default.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/default.pass.cpp
@@ -11,10 +11,13 @@
 
 // reverse_iterator
 
-// reverse_iterator();
+// constexpr reverse_iterator();
+//
+// constexpr in c++17
 
 #include <iterator>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -30,4 +33,10 @@ int main()
     test<random_access_iterator<char*> >();
     test<char*>();
     test<const char*>();
+
+#if TEST_STD_VER > 14
+    {
+        constexpr std::reverse_iterator<const char *> it;
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/iter.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/iter.pass.cpp
index ea213c0dcf0..9bded7c5a42 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/iter.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/iter.pass.cpp
@@ -11,11 +11,14 @@
 
 // reverse_iterator
 
-// explicit reverse_iterator(Iter x);
+// explicit constexpr reverse_iterator(Iter x);
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -32,4 +35,12 @@ int main()
     test(bidirectional_iterator<const char*>(s));
     test(random_access_iterator<const char*>(s));
     test(s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        constexpr std::reverse_iterator<const char *> it(p);
+        static_assert(it.base() == p);
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/reverse_iterator.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/reverse_iterator.pass.cpp
index 280e7d59ae8..2c15743db50 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/reverse_iterator.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.cons/reverse_iterator.pass.cpp
@@ -13,11 +13,14 @@
 
 // template <class U>
 //   requires HasConstructor<Iter, const U&>
-//   reverse_iterator(const reverse_iterator<U> &u);
+//   constexpr reverse_iterator(const reverse_iterator<U> &u);
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It, class U>
@@ -39,4 +42,13 @@ int main()
     test<bidirectional_iterator<Base*> >(bidirectional_iterator<Derived*>(&d));
     test<random_access_iterator<const Base*> >(random_access_iterator<Derived*>(&d));
     test<Base*>(&d);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const Derived *p = nullptr;
+        constexpr std::reverse_iterator<const Derived *>     it1 = std::make_reverse_iterator(p);
+        constexpr std::reverse_iterator<const Base *>        it2(it1);
+        static_assert(it2.base() == p);
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.make/make_reverse_iterator.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.make/make_reverse_iterator.pass.cpp
index 7ec287e5cd3..cd155988b11 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.make/make_reverse_iterator.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.make/make_reverse_iterator.pass.cpp
@@ -12,12 +12,16 @@
 
 // reverse_iterator
 
-// template <class Iterator> reverse_iterator<Iterator>
+// template <class Iterator>
+//   constexpr reverse_iterator<Iterator>
 //     make_reverse_iterator(Iterator i);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -35,5 +39,13 @@ int main()
     random_access_iterator<const char*>e(s+10);
     while ( b != e )
         test ( b++ );
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        constexpr auto it1 = std::make_reverse_iterator(p);
+        static_assert(it1.base() == p, "");
+    }
+#endif
 }
 
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op!=/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op!=/test.pass.cpp
index 29da57e3b5a..f5162a7c5dc 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op!=/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op!=/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <BidirectionalIterator Iter1, BidirectionalIterator Iter2>
 //   requires HasEqualTo<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator!=(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,16 @@ int main()
     test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
     test(s, s, false);
     test(s, s+1, true);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert(!(it1 != it2), "");
+        static_assert( (it1 != it3), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/post.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/post.pass.cpp
index bd936060c4d..6a2ab2797ca 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/post.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/post.pass.cpp
@@ -11,11 +11,14 @@
 
 // reverse_iterator
 
-// reverse_iterator operator++(int);
+// constexpr reverse_iterator operator++(int);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,17 @@ int main()
     test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
     test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s));
     test(s+1, s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p+1);
+        static_assert(it1 != it2, "");
+        constexpr RI it3 = std::make_reverse_iterator(p+1) ++;
+        static_assert(it1 != it3, "");
+        static_assert(it2 == it3, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/pre.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/pre.pass.cpp
index f68a612fae6..51024224444 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/pre.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op++/pre.pass.cpp
@@ -11,11 +11,14 @@
 
 // reverse_iterator
 
-// reverse_iterator& operator++();
+// constexpr reverse_iterator& operator++();
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,18 @@ int main()
     test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
     test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s));
     test(s+1, s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p+1);
+        static_assert(it1 != it2, "");
+        constexpr RI it3 = ++ std::make_reverse_iterator(p+1);
+        static_assert(it1 == it3, "");
+        static_assert(it2 != it3, "");
+        static_assert(*(++std::make_reverse_iterator(p+2)) == '1', "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+/difference_type.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+/difference_type.pass.cpp
index 39129d6b64d..0c9682f45c1 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+/difference_type.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+/difference_type.pass.cpp
@@ -12,11 +12,14 @@
 // reverse_iterator
 
 // requires RandomAccessIterator<Iter>
-//   reverse_iterator operator+(difference_type n) const;
+//   constexpr reverse_iterator operator+(difference_type n) const;
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -33,4 +36,17 @@ int main()
     const char* s = "1234567890";
     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
     test(s+5, 5, s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p + 5);
+        constexpr RI it3 = it2 + 5;
+        static_assert(it1 != it2, "");
+        static_assert(it1 == it3, "");
+        static_assert(it2 != it3, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+=/difference_type.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+=/difference_type.pass.cpp
index ac97aaf8c20..67ad1ae888e 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+=/difference_type.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op+=/difference_type.pass.cpp
@@ -12,11 +12,14 @@
 // reverse_iterator
 
 // requires RandomAccessIterator<Iter>
-//   reverse_iterator& operator+=(difference_type n);
+//   constexpr reverse_iterator& operator+=(difference_type n);
+//
+// constexpr in C++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,13 @@ int main()
     const char* s = "1234567890";
     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
     test(s+5, 5, s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        constexpr auto it1 = std::make_reverse_iterator(p);
+        constexpr auto it2 = std::make_reverse_iterator(p+5) += 5;
+        static_assert(it1 == it2, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/post.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/post.pass.cpp
index c3126e8c21f..5a06ea5ad14 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/post.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/post.pass.cpp
@@ -11,11 +11,14 @@
 
 // reverse_iterator
 
-// reverse_iterator operator--(int);
+// constexpr reverse_iterator operator--(int);
+//
+// constexpr in C++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,17 @@ int main()
     test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s+2));
     test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s+2));
     test(s+1, s+2);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p+1);
+        static_assert(it1 != it2, "");
+        constexpr RI it3 = std::make_reverse_iterator(p) --;
+        static_assert(it1 == it3, "");
+        static_assert(it2 != it3, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/pre.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/pre.pass.cpp
index f9361cf9c72..3265624765e 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/pre.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op--/pre.pass.cpp
@@ -11,11 +11,14 @@
 
 // reverse_iterator
 
-// reverse_iterator& operator--();
+// constexpr reverse_iterator& operator--();
+//
+// constexpr in C++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,18 @@ int main()
     test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s+2));
     test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s+2));
     test(s+1, s+2);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p+1);
+        static_assert(it1 != it2, "");
+        constexpr RI it3 = -- std::make_reverse_iterator(p);
+        static_assert(it1 != it3, "");
+        static_assert(it2 == it3, "");
+        static_assert(*(--std::make_reverse_iterator(p)) == '1', "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-/difference_type.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-/difference_type.pass.cpp
index 79d477976fb..9148cc117ca 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-/difference_type.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-/difference_type.pass.cpp
@@ -12,11 +12,14 @@
 // reverse_iterator
 
 // requires RandomAccessIterator<Iter>
-//   reverse_iterator operator-(difference_type n) const;
+//   constexpr reverse_iterator operator-(difference_type n) const;
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -33,4 +36,17 @@ int main()
     const char* s = "1234567890";
     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
     test(s+5, 5, s+10);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p + 5);
+        constexpr RI it3 = it1 - 5;
+        static_assert(it1 != it2, "");
+        static_assert(it1 != it3, "");
+        static_assert(it2 == it3, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-=/difference_type.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-=/difference_type.pass.cpp
index 93addf99dc6..3bed189dc6a 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-=/difference_type.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-=/difference_type.pass.cpp
@@ -12,11 +12,14 @@
 // reverse_iterator
 
 // requires RandomAccessIterator<Iter>
-//   reverse_iterator& operator-=(difference_type n);
+//   constexpr reverse_iterator& operator-=(difference_type n);
+//
+// constexpr in C++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,13 @@ int main()
     const char* s = "1234567890";
     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
     test(s+5, 5, s+10);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        constexpr auto it1 = std::make_reverse_iterator(p+5);
+        constexpr auto it2 = std::make_reverse_iterator(p) -= 5;
+        static_assert(it1 == it2, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op.star/op_star.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op.star/op_star.pass.cpp
index 7a7759843ee..4e727564ab7 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op.star/op_star.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op.star/op_star.pass.cpp
@@ -11,7 +11,9 @@
 
 // reverse_iterator
 
-// reference operator*() const;
+// constexpr reference operator*() const;
+//
+// constexpr in c++17
 
 // Be sure to respect LWG 198:
 //    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198
@@ -21,6 +23,8 @@
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
+
 class A
 {
     int data_;
@@ -44,4 +48,15 @@ int main()
 {
     A a;
     test(&a+1, A());
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p+1);
+        constexpr RI it2 = std::make_reverse_iterator(p+2);
+        static_assert(*it1 == p[0], "");
+        static_assert(*it2 == p[1], "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op=/reverse_iterator.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op=/reverse_iterator.pass.cpp
index 92573f9a924..78f6fc4cb26 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op=/reverse_iterator.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op=/reverse_iterator.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <class U>
 //   requires HasAssign<Iter, const U&>
-//   reverse_iterator&
+//   constexpr reverse_iterator&
 //   operator=(const reverse_iterator<U>& u);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It, class U>
@@ -42,4 +45,15 @@ int main()
     test<bidirectional_iterator<Base*> >(bidirectional_iterator<Derived*>(&d));
     test<random_access_iterator<const Base*> >(random_access_iterator<Derived*>(&d));
     test<Base*>(&d);
+
+#if TEST_STD_VER > 14
+    {
+        using BaseIter    = std::reverse_iterator<const Base *>;
+        using DerivedIter = std::reverse_iterator<const Derived *>;
+        constexpr const Derived *p = nullptr;
+        constexpr DerivedIter     it1 = std::make_reverse_iterator(p);
+        constexpr BaseIter        it2 = (BaseIter{nullptr} = it1);
+        static_assert(it2.base() == p, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op==/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op==/test.pass.cpp
index 3da4b951df1..ac9add5b9e3 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op==/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op==/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <BidirectionalIterator Iter1, BidirectionalIterator Iter2>
 //   requires HasEqualTo<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator==(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,17 @@ int main()
     test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
     test(s, s, true);
     test(s, s+1, false);
+    
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert( (it1 == it2), "");
+        static_assert(!(it1 == it3), "");
+    }
+#endif
+
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opdiff/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opdiff/test.pass.cpp
index 437bb6f9f7e..73e49027b0f 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opdiff/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opdiff/test.pass.cpp
@@ -13,13 +13,16 @@
 
 // template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
 //   requires HasMinus<Iter2, Iter1>
-//   auto operator-(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y)
+//   constexpr auto operator-(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y)
 //   -> decltype(y.base() - x.base());
+//
+// constexpr in c++17
 
 #include <iterator>
 #include <cstddef>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It1, class It2>
@@ -40,4 +43,15 @@ int main()
     test(s, s, 0);
     test(s, s+1, 1);
     test(s+1, s, -1);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p+1);
+        static_assert( it1 - it2 ==  1, "");
+        static_assert( it2 - it1 == -1, "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt/test.pass.cpp
index afbb334ebfd..b6adcf40ede 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
 //   requires HasGreater<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator>(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,16 @@ int main()
     test(s, s, false);
     test(s, s+1, true);
     test(s+1, s, false);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert(!(it1 > it2), "");
+        static_assert( (it1 > it3), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt=/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt=/test.pass.cpp
index c6e79aff126..dc917b29f90 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt=/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opgt=/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
 //   requires HasGreater<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator>=(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,16 @@ int main()
     test(s, s, true);
     test(s, s+1, true);
     test(s+1, s, false);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert( (it1 >= it2), "");
+        static_assert( (it1 >= it3), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt/test.pass.cpp
index 2b389b853a5..668f7d83975 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
 //   requires HasGreater<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator<(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,16 @@ int main()
     test(s, s, false);
     test(s, s+1, false);
     test(s+1, s, true);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert(!(it1 < it2), "");
+        static_assert(!(it1 < it3), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt=/test.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt=/test.pass.cpp
index 6c4f05cdf65..5201bc43db2 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt=/test.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.oplt=/test.pass.cpp
@@ -13,12 +13,15 @@
 
 // template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
 //   requires HasGreater<Iter1, Iter2>
-//   bool
+//   constexpr bool
 //   operator<=(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y);
+//
+//   constexpr in c++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -39,4 +42,16 @@ int main()
     test(s, s, true);
     test(s, s+1, false);
     test(s+1, s, true);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p);
+        constexpr RI it3 = std::make_reverse_iterator(p+1);
+        static_assert( (it1 <= it2), "");
+        static_assert(!(it1 <= it3), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opref/op_arrow.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opref/op_arrow.pass.cpp
index 404e8fbf19b..0202b3bdb62 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opref/op_arrow.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opref/op_arrow.pass.cpp
@@ -11,7 +11,9 @@
 
 // reverse_iterator
 
-// pointer operator->() const;
+// constexpr pointer operator->() const;
+//
+// constexpr in C++17
 
 // Be sure to respect LWG 198:
 //    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198
@@ -23,6 +25,8 @@
 #include <list>
 #include <cassert>
 
+#include "test_macros.h"
+
 class A
 {
     int data_;
@@ -59,6 +63,20 @@ public:
     B       *operator&()       { return nullptr; }
 };
 
+class C
+{
+    int data_;
+public:
+    TEST_CONSTEXPR C() : data_(1) {}
+
+    TEST_CONSTEXPR int get() const {return data_;}
+
+    friend TEST_CONSTEXPR bool operator==(const C& x, const C& y)
+        {return x.data_ == y.data_;}
+};
+
+TEST_CONSTEXPR  C gC;
+
 int main()
 {
     A a;
@@ -86,4 +104,13 @@ int main()
     assert ( ri == l.rend ());
     }
     }
+
+#if TEST_STD_VER > 14
+    {
+        typedef std::reverse_iterator<const C *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(&gC+1);
+
+        static_assert(it1->get() == gC.get(), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opsum/difference_type.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opsum/difference_type.pass.cpp
index 74747cb1f0f..00f739d09a5 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opsum/difference_type.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.opsum/difference_type.pass.cpp
@@ -12,12 +12,15 @@
 // reverse_iterator
 
 // template <RandomAccessIterator Iterator>
-//   reverse_iterator<Iter>
+//   constexpr reverse_iterator<Iter>
 //   operator+(Iter::difference_type n, const reverse_iterator<Iter>& x);
+//
+// constexpr in C++17
 
 #include <iterator>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 template <class It>
@@ -34,4 +37,17 @@ int main()
     const char* s = "1234567890";
     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
     test(s+5, 5, s);
+
+#if TEST_STD_VER > 14
+    {
+        constexpr const char *p = "123456789";
+        typedef std::reverse_iterator<const char *> RI;
+        constexpr RI it1 = std::make_reverse_iterator(p);
+        constexpr RI it2 = std::make_reverse_iterator(p + 5);
+        constexpr RI it3 = 5 + it2;
+        static_assert(it1 != it2, "");
+        static_assert(it1 == it3, "");
+        static_assert(it2 != it3, "");
+    }
+#endif
 }