1 files changed, 15 insertions, 0 deletions
diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
index 691e968ed246..35cbb2d5fd47 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
@@ -12,10 +12,21 @@
 // template<> struct char_traits<wchar_t>
 
 // static size_t length(const char_type* s);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<wchar_t>::length(L"") == 0
+        && std::char_traits<wchar_t>::length(L"abcd") == 4;
+}
+#endif
+
 int main()
 {
     assert(std::char_traits<wchar_t>::length(L"") == 0);
@@ -23,4 +34,8 @@ int main()
     assert(std::char_traits<wchar_t>::length(L"aa") == 2);
     assert(std::char_traits<wchar_t>::length(L"aaa") == 3);
     assert(std::char_traits<wchar_t>::length(L"aaaa") == 4);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }