1 files changed, 22 insertions, 1 deletions
diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/replace_copy.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/replace_copy.pass.cpp
index 3c4d0e50817..aad7f9f921d 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/replace_copy.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/replace_copy.pass.cpp
@@ -13,15 +13,32 @@
 //   requires OutputIterator<OutIter, InIter::reference>
 //         && OutputIterator<OutIter, const T&>
 //         && HasEqualTo<InIter::value_type, T>
-//   OutIter
+//   constexpr OutIter      // constexpr after C++17
 //   replace_copy(InIter first, InIter last, OutIter result, const T& old_value,
 //                                                           const T& new_value);
 
 #include <algorithm>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
+
+#if TEST_STD_VER > 17
+TEST_CONSTEXPR bool test_constexpr() {
+    int ia[] = {0, 1, 2, 3, 4};
+    int ib[] = {0, 0, 0, 0, 0, 0}; // one bigger
+    const int expected[] = {0, 1, 5, 3, 4};
+
+    auto it = std::replace_copy(std::begin(ia), std::end(ia), std::begin(ib), 2, 5);
+    
+    return it == (std::begin(ib) + std::size(ia))
+        && *it == 0 // don't overwrite the last value in the output array
+        && std::equal(std::begin(ib), it, std::begin(expected), std::end(expected))
+        ;
+    }
+#endif
+
 template <class InIter, class OutIter>
 void
 test()
@@ -69,4 +86,8 @@ int main()
     test<const int*, bidirectional_iterator<int*> >();
     test<const int*, random_access_iterator<int*> >();
     test<const int*, int*>();
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }