Implement std::string_view as described in http://wg21.link/P0254R1. Reviewed as https://reviews.llvm.org/D21459

llvm-svn: 276238

18 files changed, 1100 insertions, 0 deletions

diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..d4bf310985d
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
@@ -0,0 +1,68 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//   constexpr bool operator==(basic_string_view<charT,traits> lhs, const charT* rhs);
+// template<class charT, class traits>
+//   constexpr bool operator==(const charT* lhs, basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(S lhs, const typename S::value_type* rhs, bool x)
+{
+    assert((lhs == rhs) == x);
+    assert((rhs == lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", true);
+    test(S(""), "abcde", false);
+    test(S(""), "abcdefghij", false);
+    test(S(""), "abcdefghijklmnopqrst", false);
+    test(S("abcde"), "", false);
+    test(S("abcde"), "abcde", true);
+    test(S("abcde"), "abcdefghij", false);
+    test(S("abcde"), "abcdefghijklmnopqrst", false);
+    test(S("abcdefghij"), "", false);
+    test(S("abcdefghij"), "abcde", false);
+    test(S("abcdefghij"), "abcdefghij", true);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", false);
+    test(S("abcdefghijklmnopqrst"), "", false);
+    test(S("abcdefghijklmnopqrst"), "abcde", false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+    static_assert (  sv1     == "", "" );
+    static_assert (  ""      == sv1, "" );
+    static_assert (!(sv1     == "abcde"), "" );
+    static_assert (!("abcde" == sv1), "" );
+
+    static_assert (  sv2      == "abcde", "" );
+    static_assert (  "abcde"  == sv2, "" );
+    static_assert (!(sv2      == "abcde0"), "" );
+    static_assert (!("abcde0" == sv2), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
new file mode 100644
index 00000000000..4b107b01e2c
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator==(const charT* lhs, const basic_string<charT,traits> rhs);
+// template<class charT, class traits, class Allocator>
+//   bool operator==(const basic_string_view<charT,traits> lhs, const CharT* rhs);
+
+#include <string_view>
+#include <string>
+#include <cassert>
+
+template <class S>
+void
+test(const std::string &lhs, S rhs, bool x)
+{
+    assert((lhs == rhs) == x);
+    assert((rhs == lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), true);
+    test("", S("abcde"), false);
+    test("", S("abcdefghij"), false);
+    test("", S("abcdefghijklmnopqrst"), false);
+    test("abcde", S(""), false);
+    test("abcde", S("abcde"), true);
+    test("abcde", S("abcdefghij"), false);
+    test("abcde", S("abcdefghijklmnopqrst"), false);
+    test("abcdefghij", S(""), false);
+    test("abcdefghij", S("abcde"), false);
+    test("abcdefghij", S("abcdefghij"), true);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), false);
+    test("abcdefghijklmnopqrst", S(""), false);
+    test("abcdefghijklmnopqrst", S("abcde"), false);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), false);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
+    }
+}
+
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..a7c10e6fc5e
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string_view>
+
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator==(const basic_string_view<charT,traits> lhs,
+//                   const basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(S lhs, S rhs, bool x)
+{
+    assert((lhs == rhs) == x);
+    assert((rhs == lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), true);
+    test(S(""), S("abcde"), false);
+    test(S(""), S("abcdefghij"), false);
+    test(S(""), S("abcdefghijklmnopqrst"), false);
+    test(S("abcde"), S(""), false);
+    test(S("abcde"), S("abcde"), true);
+    test(S("abcde"), S("abcdefghij"), false);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), false);
+    test(S("abcdefghij"), S(""), false);
+    test(S("abcdefghij"), S("abcde"), false);
+    test(S("abcdefghij"), S("abcdefghij"), true);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), false);
+    test(S("abcdefghijklmnopqrst"), S(""), false);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2;
+    constexpr SV  sv3 { "abcde", 5 };
+    static_assert (  sv1 == sv2, "" );
+    static_assert (!(sv1 == sv3), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..0bbba5b1252
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator>=(const charT* lhs, basic_string_wiew<charT,traits> rhs);
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator>=(basic_string_wiew<charT,traits> lhs, const charT* rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs >= rhs) == x);
+    assert((rhs >= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), true, true);
+    test("", S("abcde"), false, true);
+    test("", S("abcdefghij"), false, true);
+    test("", S("abcdefghijklmnopqrst"), false, true);
+    test("abcde", S(""), true, false);
+    test("abcde", S("abcde"), true, true);
+    test("abcde", S("abcdefghij"), false, true);
+    test("abcde", S("abcdefghijklmnopqrst"), false, true);
+    test("abcdefghij", S(""), true, false);
+    test("abcdefghij", S("abcde"), true, false);
+    test("abcdefghij", S("abcdefghij"), true, true);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), false, true);
+    test("abcdefghijklmnopqrst", S(""), true, false);
+    test("abcdefghijklmnopqrst", S("abcde"), true, false);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), true, false);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true, true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (  sv1     >= "", "" );
+    static_assert (  ""      >= sv1, "" );
+    static_assert (!(sv1     >= "abcde"), "" );
+    static_assert (  "abcde" >= sv1, "" );
+
+    static_assert (  sv2      >= "", "" );
+    static_assert (!(""       >= sv2), "" );
+    static_assert (  sv2      >= "abcde", "" );
+    static_assert (  "abcde"  >= sv2, "" );
+    static_assert (!(sv2      >= "abcde0"), "" );
+    static_assert (  "abcde0" >= sv2, "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
new file mode 100644
index 00000000000..3881372ffc3
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator>=(const basic_string<charT,traits,Allocator>& lhs,
+//                   basic_string_view<charT,traits> rhs);
+//   bool operator>=(basic_string_view<charT,traits> lhs,
+//            const basic_string<charT,traits,Allocator>&  rhs);
+
+#include <string_view>
+#include <cassert>
+
+template <class S>
+void
+test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
+{
+    assert((lhs >= rhs) == x);
+    assert((rhs >= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", true, true);
+    test(S(""), "abcde", false, true);
+    test(S(""), "abcdefghij", false, true);
+    test(S(""), "abcdefghijklmnopqrst", false, true);
+    test(S("abcde"), "", true, false);
+    test(S("abcde"), "abcde", true, true);
+    test(S("abcde"), "abcdefghij", false, true);
+    test(S("abcde"), "abcdefghijklmnopqrst", false, true);
+    test(S("abcdefghij"), "", true, false);
+    test(S("abcdefghij"), "abcde", true, false);
+    test(S("abcdefghij"), "abcdefghij", true, true);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", false, true);
+    test(S("abcdefghijklmnopqrst"), "", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcde", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
+    }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..580ea463187
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//   constexpr bool operator>=(basic_string_view<charT,traits> lhs,
+//                  basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const S& lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs >= rhs) == x);
+    assert((rhs >= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), true, true);
+    test(S(""), S("abcde"), false, true);
+    test(S(""), S("abcdefghij"), false, true);
+    test(S(""), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcde"), S(""), true, false);
+    test(S("abcde"), S("abcde"), true, true);
+    test(S("abcde"), S("abcdefghij"), false, true);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcdefghij"), S(""), true, false);
+    test(S("abcdefghij"), S("abcde"), true, false);
+    test(S("abcdefghij"), S("abcdefghij"), true, true);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcdefghijklmnopqrst"), S(""), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true, true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (  sv1 >= sv1,  "" );
+    static_assert (  sv2 >= sv2,  "" );
+
+    static_assert (!(sv1 >= sv2), "" );
+    static_assert (  sv2 >= sv1,  "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..124c28535cf
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// constexpr template<class charT, class traits, class Allocator>
+//   bool operator>(const charT* lhs, basic_string_wiew<charT,traits> rhs);
+// constexpr template<class charT, class traits, class Allocator>
+//   bool operator>(basic_string_wiew<charT,traits> lhs, const charT* rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs > rhs) == x);
+    assert((rhs > lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), false, false);
+    test("", S("abcde"), false, true);
+    test("", S("abcdefghij"), false, true);
+    test("", S("abcdefghijklmnopqrst"), false, true);
+    test("abcde", S(""), true, false);
+    test("abcde", S("abcde"), false, false);
+    test("abcde", S("abcdefghij"), false, true);
+    test("abcde", S("abcdefghijklmnopqrst"), false, true);
+    test("abcdefghij", S(""), true, false);
+    test("abcdefghij", S("abcde"), true, false);
+    test("abcdefghij", S("abcdefghij"), false, false);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), false, true);
+    test("abcdefghijklmnopqrst", S(""), true, false);
+    test("abcdefghijklmnopqrst", S("abcde"), true, false);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), true, false);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false, false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (!(sv1     > ""), "" );
+    static_assert (!(""      > sv1), "" );
+    static_assert (!(sv1     > "abcde"), "" );
+    static_assert (  "abcde" > sv1, "" );
+
+    static_assert (  sv2      > "", "" );
+    static_assert (!(""       > sv2), "" );
+    static_assert (!(sv2      > "abcde"), "" );
+    static_assert (!("abcde"  > sv2), "" );
+    static_assert (!(sv2      > "abcde0"), "" );
+    static_assert (  "abcde0" > sv2, "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
new file mode 100644
index 00000000000..f0058c809e4
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator>(const basic_string<charT,traits,Allocator>& lhs,
+//                   basic_string_view<charT,traits> rhs);
+//   bool operator>(basic_string_view<charT,traits> lhs,
+//            const basic_string<charT,traits,Allocator>&  rhs);
+
+#include <string_view>
+#include <cassert>
+
+template <class S>
+void
+test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
+{
+    assert((lhs > rhs) == x);
+    assert((rhs > lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", false, false);
+    test(S(""), "abcde", false, true);
+    test(S(""), "abcdefghij", false, true);
+    test(S(""), "abcdefghijklmnopqrst", false, true);
+    test(S("abcde"), "", true, false);
+    test(S("abcde"), "abcde", false, false);
+    test(S("abcde"), "abcdefghij", false, true);
+    test(S("abcde"), "abcdefghijklmnopqrst", false, true);
+    test(S("abcdefghij"), "", true, false);
+    test(S("abcdefghij"), "abcde", true, false);
+    test(S("abcdefghij"), "abcdefghij", false, false);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", false, true);
+    test(S("abcdefghijklmnopqrst"), "", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcde", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
+    }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..8d8a922aabf
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//  constexpr bool operator>(basic_string_view<charT,traits> lhs,
+//                  basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const S& lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs > rhs) == x);
+    assert((rhs > lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), false, false);
+    test(S(""), S("abcde"), false, true);
+    test(S(""), S("abcdefghij"), false, true);
+    test(S(""), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcde"), S(""), true, false);
+    test(S("abcde"), S("abcde"), false, false);
+    test(S("abcde"), S("abcdefghij"), false, true);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcdefghij"), S(""), true, false);
+    test(S("abcdefghij"), S("abcde"), true, false);
+    test(S("abcdefghij"), S("abcdefghij"), false, false);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), false, true);
+    test(S("abcdefghijklmnopqrst"), S(""), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), true, false);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false, false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (!(sv1 > sv1), "" );
+    static_assert (!(sv2 > sv2), "" );
+
+    static_assert (!(sv1 > sv2), "" );
+    static_assert (  sv2 > sv1, "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..6fdabb1a1a0
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator<=(const charT* lhs, basic_string_wiew<charT,traits> rhs);
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator<=(basic_string_wiew<charT,traits> lhs, const charT* rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs <= rhs) == x);
+    assert((rhs <= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), true, true);
+    test("", S("abcde"), true, false);
+    test("", S("abcdefghij"), true, false);
+    test("", S("abcdefghijklmnopqrst"), true, false);
+    test("abcde", S(""), false, true);
+    test("abcde", S("abcde"), true, true);
+    test("abcde", S("abcdefghij"), true, false);
+    test("abcde", S("abcdefghijklmnopqrst"), true, false);
+    test("abcdefghij", S(""), false, true);
+    test("abcdefghij", S("abcde"), false, true);
+    test("abcdefghij", S("abcdefghij"), true, true);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), true, false);
+    test("abcdefghijklmnopqrst", S(""), false, true);
+    test("abcdefghijklmnopqrst", S("abcde"), false, true);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), false, true);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true, true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (  sv1     <= "", "" );
+    static_assert (  ""      <= sv1, "" );
+    static_assert (  sv1     <= "abcde", "" );
+    static_assert (!("abcde" <= sv1), "" );
+
+    static_assert (!(sv2      <= ""), "" );
+    static_assert (  ""       <= sv2, "" );
+    static_assert (  sv2      <= "abcde", "" );
+    static_assert (  "abcde"  <= sv2, "" );
+    static_assert (  sv2      <= "abcde0", "" );
+    static_assert (!("abcde0" <= sv2), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
new file mode 100644
index 00000000000..092bc23b1c1
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator<=(const basic_string<charT,traits,Allocator>& lhs,
+//                   basic_string_view<charT,traits> rhs);
+//   bool operator<=(basic_string_view<charT,traits> lhs,
+//            const basic_string<charT,traits,Allocator>&  rhs);
+
+#include <string_view>
+#include <cassert>
+
+template <class S>
+void
+test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
+{
+    assert((lhs <= rhs) == x);
+    assert((rhs <= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", true, true);
+    test(S(""), "abcde", true, false);
+    test(S(""), "abcdefghij", true, false);
+    test(S(""), "abcdefghijklmnopqrst", true, false);
+    test(S("abcde"), "", false, true);
+    test(S("abcde"), "abcde", true, true);
+    test(S("abcde"), "abcdefghij", true, false);
+    test(S("abcde"), "abcdefghijklmnopqrst", true, false);
+    test(S("abcdefghij"), "", false, true);
+    test(S("abcdefghij"), "abcde", false, true);
+    test(S("abcdefghij"), "abcdefghij", true, true);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", true, false);
+    test(S("abcdefghijklmnopqrst"), "", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcde", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
+    }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..1fab355097b
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//   constexpr bool operator<=(basic_string_view<charT,traits> lhs,
+//                  basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const S& lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs <= rhs) == x);
+    assert((rhs <= lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), true, true);
+    test(S(""), S("abcde"), true, false);
+    test(S(""), S("abcdefghij"), true, false);
+    test(S(""), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcde"), S(""), false, true);
+    test(S("abcde"), S("abcde"), true, true);
+    test(S("abcde"), S("abcdefghij"), true, false);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcdefghij"), S(""), false, true);
+    test(S("abcdefghij"), S("abcde"), false, true);
+    test(S("abcdefghij"), S("abcdefghij"), true, true);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcdefghijklmnopqrst"), S(""), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true, true);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (  sv1 <= sv1,  "" );
+    static_assert (  sv2 <= sv2,  "" );
+
+    static_assert (  sv1 <= sv2,  "" );
+    static_assert (!(sv2 <= sv1), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..47726869676
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator<(const charT* lhs, basic_string_wiew<charT,traits> rhs);
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator<(basic_string_wiew<charT,traits> lhs, const charT* rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs < rhs) == x);
+    assert((rhs < lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), false, false);
+    test("", S("abcde"), true, false);
+    test("", S("abcdefghij"), true, false);
+    test("", S("abcdefghijklmnopqrst"), true, false);
+    test("abcde", S(""), false, true);
+    test("abcde", S("abcde"), false, false);
+    test("abcde", S("abcdefghij"), true, false);
+    test("abcde", S("abcdefghijklmnopqrst"), true, false);
+    test("abcdefghij", S(""), false, true);
+    test("abcdefghij", S("abcde"), false, true);
+    test("abcdefghij", S("abcdefghij"), false, false);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), true, false);
+    test("abcdefghijklmnopqrst", S(""), false, true);
+    test("abcdefghijklmnopqrst", S("abcde"), false, true);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), false, true);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false, false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (!(sv1     < ""), "" );
+    static_assert (!(""      < sv1), "" );
+    static_assert (  sv1     < "abcde", "" );
+    static_assert (!("abcde" < sv1), "" );
+
+    static_assert (!(sv2      < ""), "" );
+    static_assert (  ""       < sv2, "" );
+    static_assert (!(sv2      < "abcde"), "" );
+    static_assert (!("abcde"  < sv2), "" );
+    static_assert (  sv2      < "abcde0", "" );
+    static_assert (!("abcde0" < sv2), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
new file mode 100644
index 00000000000..609edd764cf
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator<(const basic_string<charT,traits,Allocator>& lhs,
+//                   basic_string_view<charT,traits> rhs);
+//   bool operator<(basic_string_view<charT,traits> lhs,
+//            const basic_string<charT,traits,Allocator>&  rhs);
+
+#include <string_view>
+#include <cassert>
+
+template <class S>
+void
+test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
+{
+    assert((lhs < rhs) == x);
+    assert((rhs < lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", false, false);
+    test(S(""), "abcde", true, false);
+    test(S(""), "abcdefghij", true, false);
+    test(S(""), "abcdefghijklmnopqrst", true, false);
+    test(S("abcde"), "", false, true);
+    test(S("abcde"), "abcde", false, false);
+    test(S("abcde"), "abcdefghij", true, false);
+    test(S("abcde"), "abcdefghijklmnopqrst", true, false);
+    test(S("abcdefghij"), "", false, true);
+    test(S("abcdefghij"), "abcde", false, true);
+    test(S("abcdefghij"), "abcdefghij", false, false);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", true, false);
+    test(S("abcdefghijklmnopqrst"), "", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcde", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
+    }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..66b6f03dbb5
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//   constexpr bool operator<(basic_string_view<charT,traits> lhs,
+//                  basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(const S& lhs, const S& rhs, bool x, bool y)
+{
+    assert((lhs < rhs) == x);
+    assert((rhs < lhs) == y);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), false, false);
+    test(S(""), S("abcde"), true, false);
+    test(S(""), S("abcdefghij"), true, false);
+    test(S(""), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcde"), S(""), false, true);
+    test(S("abcde"), S("abcde"), false, false);
+    test(S("abcde"), S("abcdefghij"), true, false);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcdefghij"), S(""), false, true);
+    test(S("abcdefghij"), S("abcde"), false, true);
+    test(S("abcdefghij"), S("abcdefghij"), false, false);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), true, false);
+    test(S("abcdefghijklmnopqrst"), S(""), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), false, true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false, false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (!(sv1 < sv1), "" );
+    static_assert (!(sv2 < sv2), "" );
+
+    static_assert (  sv1 < sv2,  "" );
+    static_assert (!(sv2 < sv1), "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
new file mode 100644
index 00000000000..20b3defa137
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
@@ -0,0 +1,69 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits>
+//   constexpr bool operator!=(basic_string_view<charT,traits> lhs, const charT* rhs);
+// template<class charT, class traits>
+//   constexpr bool operator!=(const charT* lhs, basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(S lhs, const typename S::value_type* rhs, bool x)
+{
+    assert((lhs != rhs) == x);
+    assert((rhs != lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), "", false);
+    test(S(""), "abcde", true);
+    test(S(""), "abcdefghij", true);
+    test(S(""), "abcdefghijklmnopqrst", true);
+    test(S("abcde"), "", true);
+    test(S("abcde"), "abcde", false);
+    test(S("abcde"), "abcdefghij", true);
+    test(S("abcde"), "abcdefghijklmnopqrst", true);
+    test(S("abcdefghij"), "", true);
+    test(S("abcdefghij"), "abcde", true);
+    test(S("abcdefghij"), "abcdefghij", false);
+    test(S("abcdefghij"), "abcdefghijklmnopqrst", true);
+    test(S("abcdefghijklmnopqrst"), "", true);
+    test(S("abcdefghijklmnopqrst"), "abcde", true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghij", true);
+    test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2 { "abcde", 5 };
+
+    static_assert (!(sv1     != ""), "" );
+    static_assert (!(""      != sv1), "" );
+    static_assert (  sv1     != "abcde", "" );
+    static_assert (  "abcde" != sv1, "" );
+
+    static_assert (!(sv2      != "abcde"), "" );
+    static_assert (!("abcde"  != sv2), "" );
+    static_assert (  sv2      != "abcde0",   "" );
+    static_assert (  "abcde0" != sv2, "" );
+    }
+#endif
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
new file mode 100644
index 00000000000..0c981e21d2a
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// template<class charT, class traits, class Allocator>
+//   bool operator!=(const basic_string<charT, traits, Allocator> &lhs, basic_string_view<charT,traits> rhs);
+// template<class charT, class traits, class Allocator>
+//   bool operator!=(basic_string_view<charT,traits> lhs, const basic_string<charT, traits, Allocator> &rhs);
+
+#include <string_view>
+#include <string>
+#include <cassert>
+
+template <class S>
+void
+test(const std::string &lhs, S rhs, bool x)
+{
+    assert((lhs != rhs) == x);
+    assert((rhs != lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test("", S(""), false);
+    test("", S("abcde"), true);
+    test("", S("abcdefghij"), true);
+    test("", S("abcdefghijklmnopqrst"), true);
+    test("abcde", S(""), true);
+    test("abcde", S("abcde"), false);
+    test("abcde", S("abcdefghij"), true);
+    test("abcde", S("abcdefghijklmnopqrst"), true);
+    test("abcdefghij", S(""), true);
+    test("abcdefghij", S("abcde"), true);
+    test("abcdefghij", S("abcdefghij"), false);
+    test("abcdefghij", S("abcdefghijklmnopqrst"), true);
+    test("abcdefghijklmnopqrst", S(""), true);
+    test("abcdefghijklmnopqrst", S("abcde"), true);
+    test("abcdefghijklmnopqrst", S("abcdefghij"), true);
+    test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
+    }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
new file mode 100644
index 00000000000..0030366a2f2
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string_view>
+
+// template<class charT, class traits, class Allocator>
+//   constexpr bool operator!=(const basic_string_view<charT,traits> lhs,
+//                   const basic_string_view<charT,traits> rhs);
+
+#include <string_view>
+#include <cassert>
+
+#include "constexpr_char_traits.hpp"
+
+template <class S>
+void
+test(S lhs, S rhs, bool x)
+{
+    assert((lhs != rhs) == x);
+    assert((rhs != lhs) == x);
+}
+
+int main()
+{
+    {
+    typedef std::string_view S;
+    test(S(""), S(""), false);
+    test(S(""), S("abcde"), true);
+    test(S(""), S("abcdefghij"), true);
+    test(S(""), S("abcdefghijklmnopqrst"), true);
+    test(S("abcde"), S(""), true);
+    test(S("abcde"), S("abcde"), false);
+    test(S("abcde"), S("abcdefghij"), true);
+    test(S("abcde"), S("abcdefghijklmnopqrst"), true);
+    test(S("abcdefghij"), S(""), true);
+    test(S("abcdefghij"), S("abcde"), true);
+    test(S("abcdefghij"), S("abcdefghij"), false);
+    test(S("abcdefghij"), S("abcdefghijklmnopqrst"), true);
+    test(S("abcdefghijklmnopqrst"), S(""), true);
+    test(S("abcdefghijklmnopqrst"), S("abcde"), true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghij"), true);
+    test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
+    }
+
+#if _LIBCPP_STD_VER > 11
+    {
+    typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
+    constexpr SV  sv1;
+    constexpr SV  sv2;
+    constexpr SV  sv3 { "abcde", 5 };
+    static_assert (!( sv1 != sv2), "" );
+    static_assert (   sv1 != sv3,  "" );
+    }
+#endif
+}