diff --git a/libcxx/test/std/strings/basic.string/string.contains/contains.char.pass.cpp b/libcxx/test/std/strings/basic.string/string.contains/contains.char.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.contains/contains.char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.contains/contains.char.pass.cpp
@@ -35,7 +35,10 @@
 
 int main(int, char**)
 {
-    test();
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
-    return 0;
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.contains/contains.ptr.pass.cpp b/libcxx/test/std/strings/basic.string/string.contains/contains.ptr.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.contains/contains.ptr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.contains/contains.ptr.pass.cpp
@@ -65,7 +65,10 @@
 
 int main(int, char**)
 {
-    test();
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
-    return 0;
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.contains/contains.string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.contains/contains.string_view.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.contains/contains.string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.contains/contains.string_view.pass.cpp
@@ -86,7 +86,10 @@
 
 int main(int, char**)
 {
-    test();
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
-    return 0;
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
@@ -16,9 +16,8 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     S  s1 {};
     S  s2 { "abcde", 5 };
@@ -29,7 +28,17 @@
     assert (!s1.ends_with('x'));
     assert ( s2.ends_with('e'));
     assert (!s2.ends_with('x'));
-    }
+  }
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
@@ -16,9 +16,8 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     const char *s = "abcde";
 
@@ -58,7 +57,16 @@
     assert (!sNot.ends_with("bcde"));
     assert (!sNot.ends_with("abcde"));
     assert ( sNot.ends_with("def"));
-    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
@@ -16,9 +16,8 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     typedef std::string_view SV;
     const char *s = "abcde";
@@ -67,7 +66,16 @@
     assert (!sNot.ends_with(sv4));
     assert (!sNot.ends_with(sv5));
     assert ( sNot.ends_with(svNot));
-    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
@@ -18,7 +18,7 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(S s)
 {
     const S& cs = s;
@@ -31,19 +31,28 @@
     assert(b == cb);
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
@@ -17,7 +17,7 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(const S& s)
 {
     typename S::const_iterator cb = s.cbegin();
@@ -28,19 +28,28 @@
     assert(cb == s.begin());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
@@ -24,20 +24,28 @@
     assert(ce == s.end());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
 #endif
 
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
@@ -17,7 +17,7 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(const S& s)
 {
     typename S::const_reverse_iterator cb = s.crbegin();
@@ -28,19 +28,28 @@
     assert(cb == s.rbegin());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
@@ -17,26 +17,35 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(const S& s)
 {
     typename S::const_reverse_iterator ce = s.crend();
     assert(ce == s.rend());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
@@ -19,7 +19,7 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(S s)
 {
     const S& cs = s;
@@ -34,19 +34,28 @@
     assert(static_cast<std::size_t>(ce - cs.begin()) == cs.size());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
@@ -18,7 +18,7 @@
 #include "min_allocator.h"
 
 template <class S>
-void
+TEST_CONSTEXPR_CXX20 void
 test(S s)
 {
     const S& cs = s;
@@ -31,19 +31,28 @@
     assert(b == cb);
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
@@ -34,19 +34,28 @@
     assert(static_cast<std::size_t>(ce - cs.rbegin()) == cs.size());
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test(S());
     test(S("123"));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S());
     test(S("123"));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp b/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
@@ -25,30 +25,39 @@
         assert ( *(c.begin() + static_cast<typename C::difference_type>(i)) == *(std::addressof(*c.begin()) + i));
 }
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     test_contiguous(S());
     test_contiguous(S("1"));
     test_contiguous(S("1234567890123456789012345678901234567890123456789012345678901234567890"));
-    }
+  }
 
-    {
+  {
     typedef test_allocator<char> A;
     typedef std::basic_string<char, std::char_traits<char>, A> S;
     test_contiguous(S(A(3)));
     test_contiguous(S("1", A(5)));
     test_contiguous(S("1234567890123456789012345678901234567890123456789012345678901234567890", A(7)));
-    }
+  }
 #if TEST_STD_VER >= 11
-    {
+  {
     typedef min_allocator<char> A;
     typedef std::basic_string<char, std::char_traits<char>, A> S;
     test_contiguous(S(A{}));
     test_contiguous(S("1", A()));
     test_contiguous(S("1234567890123456789012345678901234567890123456789012345678901234567890", A()));
-    }
+  }
+#endif
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
 #endif
 
   return 0;
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
@@ -16,9 +16,8 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     S  s1 {};
     S  s2 { "abcde", 5 };
@@ -29,7 +28,17 @@
     assert (!s1.starts_with('x'));
     assert ( s2.starts_with('a'));
     assert (!s2.starts_with('x'));
-    }
+  }
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
@@ -16,9 +16,8 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
+  {
     typedef std::string S;
     const char *s = "abcde";
     S  s0 {};
@@ -57,7 +56,17 @@
     assert (!sNot.starts_with("abcd"));
     assert (!sNot.starts_with("abcde"));
     assert ( sNot.starts_with("def"));
-    }
+  }
+
+  return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
@@ -16,9 +16,7 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-    {
+bool test() {
     typedef std::string S;
     typedef std::string_view SV;
     const char *s = "abcde";
@@ -67,7 +65,16 @@
     assert (!sNot.starts_with(sv4));
     assert (!sNot.starts_with(sv5));
     assert ( sNot.starts_with(svNot));
-    }
+
+    return true;
+}
+
+int main(int, char**)
+{
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }