[libc++] Implement P1423R3 (char8_t backward compatibility remediation)

Reviewed By: Mordante, #libc

Spies: h-vetinari, libcxx-commits, arichardson

Differential Revision: https://reviews.llvm.org/D129195

2 files changed, 82 insertions, 2 deletions

diff --git a/libcxx/include/ostream b/libcxx/include/ostream
index ee220f3023aa..14b49d78cb03 100644
--- a/libcxx/include/ostream
+++ b/libcxx/include/ostream
@@ -130,6 +130,35 @@ template <class charT, class traits>
 template <class Stream, class T>
   Stream&& operator<<(Stream&& os, const T& x);
 
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, wchar_t) = delete;               // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char8_t) = delete;               // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char16_t) = delete;              // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, char32_t) = delete;              // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, char8_t) = delete;         // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, char16_t) = delete;        // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, char32_t) = delete;        // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const wchar_t*) = delete;        // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const char8_t*) = delete;        // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const char16_t*) = delete;       // since C++20
+template<class traits>
+basic_ostream<char, traits>& operator<<(basic_ostream<char, traits>&, const char32_t*) = delete;       // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, const char8_t*) = delete;  // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, const char16_t*) = delete; // since C++20
+template<class traits>
+basic_ostream<wchar_t, traits>& operator<<(basic_ostream<wchar_t, traits>&, const char32_t*) = delete; // since C++20
+
 }  // std
 
 */
@@ -1102,6 +1131,57 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const bitset<_Size>& __x)
                          use_facet<ctype<_CharT> >(__os.getloc()).widen('1'));
 }
 
+#if _LIBCPP_STD_VER > 17
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, wchar_t) = delete;
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const wchar_t*) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, char16_t) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, char32_t) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, const char16_t*) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, const char32_t*) = delete;
+
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, char8_t) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, char8_t) = delete;
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const char8_t*) = delete;
+
+template <class _Traits>
+basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, const char8_t*) = delete;
+#endif
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, char16_t) = delete;
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, char32_t) = delete;
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const char16_t*) = delete;
+
+template <class _Traits>
+basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const char32_t*) = delete;
+
+#endif // _LIBCPP_STD_VER > 17
+
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<char>;
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<wchar_t>;
diff --git a/libcxx/include/version b/libcxx/include/version
index 2034e4b1f3d9..1df51fa1cb86 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -47,7 +47,7 @@ __cpp_lib_bounded_array_traits                          201902L <type_traits>
 __cpp_lib_boyer_moore_searcher                          201603L <functional>
 __cpp_lib_byte                                          201603L <cstddef>
 __cpp_lib_byteswap                                      202110L <bit>
-__cpp_lib_char8_t                                       201811L <atomic> <filesystem> <istream>
+__cpp_lib_char8_t                                       201907L <atomic> <filesystem> <istream>
                                                                 <limits> <locale> <ostream>
                                                                 <string> <string_view>
 __cpp_lib_chrono                                        201611L <chrono>
@@ -308,7 +308,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 // # define __cpp_lib_bitops                               201907L
 # define __cpp_lib_bounded_array_traits                 201902L
 # if !defined(_LIBCPP_HAS_NO_CHAR8_T)
-#   define __cpp_lib_char8_t                            201811L
+#   define __cpp_lib_char8_t                            201907L
 # endif
 # define __cpp_lib_concepts                             202002L
 # define __cpp_lib_constexpr_algorithms                 201806L