Make next/prev/advance/distance operations on iterators be constexpr. I missed this when I implemented the rest of P0031R0

llvm-svn: 303281

4 files changed, 116 insertions, 3 deletions

diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.pass.cpp
index e395da299dc..e5bd5603b8e 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/advance.pass.cpp
@@ -9,14 +9,16 @@
 
 // <iterator>
 
+//   All of these became constexpr in C++17
+//
 // template <InputIterator Iter>
-//   void advance(Iter& i, Iter::difference_type n);
+//   constexpr void advance(Iter& i, Iter::difference_type n);
 //
 // template <BidirectionalIterator Iter>
-//   void advance(Iter& i, Iter::difference_type n);
+//   constexpr void advance(Iter& i, Iter::difference_type n);
 //
 // template <RandomAccessIterator Iter>
-//   void advance(Iter& i, Iter::difference_type n);
+//   constexpr void advance(Iter& i, Iter::difference_type n);
 
 #include <iterator>
 #include <cassert>
@@ -31,8 +33,19 @@ test(It i, typename std::iterator_traits<It>::difference_type n, It x)
     assert(i == x);
 }
 
+#if TEST_STD_VER > 14
+template <class It>
+constexpr bool 
+constepxr_test(It i, typename std::iterator_traits<It>::difference_type n, It x)
+{
+    std::advance(i, n);
+    return i == x;
+}
+#endif
+
 int main()
 {
+    {
     const char* s = "1234567890";
     test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10));
     test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
@@ -42,4 +55,18 @@ int main()
     test(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
     test(s+5, 5, s+10);
     test(s+5, -5, s);
+    }
+#if TEST_STD_VER > 14
+    {
+    constexpr const char* s = "1234567890";
+    static_assert( constepxr_test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10)), "" );
+    static_assert( constepxr_test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10)), "" );
+    static_assert( constepxr_test(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10)), "" );
+    static_assert( constepxr_test(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s)), "" );
+    static_assert( constepxr_test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10)), "" );
+    static_assert( constepxr_test(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s)), "" );
+    static_assert( constepxr_test(s+5, 5, s+10), "" );
+    static_assert( constepxr_test(s+5, -5, s), "" );
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/distance.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/distance.pass.cpp
index 7fef635838c..2f16fcb3823 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/distance.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/distance.pass.cpp
@@ -29,12 +29,33 @@ test(It first, It last, typename std::iterator_traits<It>::difference_type x)
     assert(std::distance(first, last) == x);
 }
 
+#if TEST_STD_VER > 14
+template <class It>
+constexpr bool
+constexpr_test(It first, It last, typename std::iterator_traits<It>::difference_type x)
+{
+    return std::distance(first, last) == x;
+}
+#endif
+
 int main()
 {
+    {
     const char* s = "1234567890";
     test(input_iterator<const char*>(s), input_iterator<const char*>(s+10), 10);
     test(forward_iterator<const char*>(s), forward_iterator<const char*>(s+10), 10);
     test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+10), 10);
     test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+10), 10);
     test(s, s+10, 10);
+    }
+#if TEST_STD_VER > 14
+    {
+    constexpr const char* s = "1234567890";
+    static_assert( constexpr_test(input_iterator<const char*>(s), input_iterator<const char*>(s+10), 10), "");
+    static_assert( constexpr_test(forward_iterator<const char*>(s), forward_iterator<const char*>(s+10), 10), "");
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+10), 10), "");
+    static_assert( constexpr_test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+10), 10), "");
+    static_assert( constexpr_test(s, s+10, 10), "");
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
index 0952588b0cb..e257b3eaaf3 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
@@ -33,8 +33,25 @@ test(It i, It x)
     assert(std::next(i) == x);
 }
 
+#if TEST_STD_VER > 14
+template <class It>
+constexpr bool
+constexpr_test(It i, typename std::iterator_traits<It>::difference_type n, It x)
+{
+    return std::next(i, n) == x;
+}
+
+template <class It>
+constexpr bool
+constexpr_test(It i, It x)
+{
+    return std::next(i) == x;
+}
+#endif
+
 int main()
 {
+    {
     const char* s = "1234567890";
     test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10));
     test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
@@ -47,4 +64,21 @@ int main()
     test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1));
     test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1));
     test(s, s+1);
+    }
+#if TEST_STD_VER > 14
+    {
+    constexpr const char* s = "1234567890";
+    static_assert( constexpr_test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(s, 10, s+10), "" );
+
+    static_assert( constexpr_test(input_iterator<const char*>(s), input_iterator<const char*>(s+1)), "" );
+    static_assert( constexpr_test(forward_iterator<const char*>(s), forward_iterator<const char*>(s+1)), "" );
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1)), "" );
+    static_assert( constexpr_test(s, s+1), "" );
+    }
+#endif
 }
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
index 0641706c928..465cda1c47e 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
@@ -31,8 +31,25 @@ test(It i, It x)
     assert(std::prev(i) == x);
 }
 
+#if TEST_STD_VER > 14
+template <class It>
+constexpr bool
+constexpr_test(It i, typename std::iterator_traits<It>::difference_type n, It x)
+{
+    return std::prev(i, n) == x;
+}
+
+template <class It>
+constexpr bool
+constexpr_test(It i, It x)
+{
+    return std::prev(i) == x;
+}
+#endif
+
 int main()
 {
+    {
     const char* s = "1234567890";
     test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s));
     test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s));
@@ -41,4 +58,18 @@ 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* s = "1234567890";
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(s+10, 10, s), "" );
+
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(s+1, s), "" );
+    }
+#endif
+    
 }