1 files changed, 16 insertions, 0 deletions
diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
index 56844ef46644..d93e499873b6 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
@@ -12,10 +12,22 @@
 // template<> struct char_traits<char>
 
 // 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<char>::length("") == 0
+        && std::char_traits<char>::length("abcd") == 4;
+}
+#endif
+
+
 int main()
 {
     assert(std::char_traits<char>::length("") == 0);
@@ -23,4 +35,8 @@ int main()
     assert(std::char_traits<char>::length("aa") == 2);
     assert(std::char_traits<char>::length("aaa") == 3);
     assert(std::char_traits<char>::length("aaaa") == 4);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }