1 files changed, 14 insertions, 0 deletions
diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
index 7f223af57414..e28f906c05bb 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
@@ -12,12 +12,22 @@
 // template<> struct char_traits<char16_t>
 
 // static void assign(char_type& c1, const char_type& c2);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    char16_t c = u'1';
+    std::char_traits<char16_t>::assign(c, u'a');
+    return c == u'a';
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -26,5 +36,9 @@ int main()
     std::char_traits<char16_t>::assign(c, u'a');
     assert(c == u'a');
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }