1 files changed, 17 insertions, 3 deletions
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
index b837a0e514c..ff3b6888aa0 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count_if.pass.cpp
@@ -11,21 +11,31 @@
 
 // template<InputIterator Iter, Predicate<auto, Iter::value_type> Pred>
 //   requires CopyConstructible<Pred>
-//   Iter::difference_type
+//   constexpr Iter::difference_type   // constexpr after C++17
 //   count_if(Iter first, Iter last, Pred pred);
 
 #include <algorithm>
 #include <functional>
 #include <cassert>
 
+#include "test_macros.h"
 #include "test_iterators.h"
 
 struct eq {
-    eq (int val) : v(val) {}
-    bool operator () (int v2) const { return v == v2; }
+    TEST_CONSTEXPR eq (int val) : v(val) {}
+    TEST_CONSTEXPR bool operator () (int v2) const { return v == v2; }
     int v;
     };
 
+#if TEST_STD_VER > 17
+TEST_CONSTEXPR bool test_constexpr() {
+    int ia[] = {0, 1, 2, 2, 0, 1, 2, 3};
+    int ib[] = {1, 2, 3, 4, 5, 6};
+    return    (std::count_if(std::begin(ia), std::end(ia), eq(2)) == 3)
+           && (std::count_if(std::begin(ib), std::end(ib), eq(9)) == 0)
+           ;
+    }
+#endif
 
 int main()
 {
@@ -40,4 +50,8 @@ int main()
     assert(std::count_if(input_iterator<const int*>(ia),
                          input_iterator<const int*>(ia),
                          eq(2)) == 0);
+
+#if TEST_STD_VER > 17
+    static_assert(test_constexpr());
+#endif
 }