[libc++] Remove deprecated char_traits base template

libcxx/docs/ReleaseNotes/19.rst

@@ -56,7 +56,7 @@ Deprecations and Removals
   the LLVM 19 release while also issuing a deprecation warning). See :ref:`the hardening documentation
   <using-hardening-modes>` for more details.
 
-- TODO: The base template for ``std::char_traits`` has been removed in LLVM 19. If you are using ``std::char_traits`` with
+- The base template for ``std::char_traits`` has been removed in LLVM 19. If you are using ``std::char_traits`` with
   types other than ``char``, ``wchar_t``, ``char8_t``, ``char16_t``, ``char32_t`` or a custom character type for which you
   specialized ``std::char_traits``, your code will stop working. The Standard does not mandate that a base template is
   provided, and such a base template is bound to be incorrect for some types, which could currently cause unexpected behavior

libcxx/include/__string/char_traits.h

@@ -72,106 +72,6 @@ exposition-only to document what members a char_traits specialization should pro
 };
 */
 
-//
-// Temporary extension to provide a base template for std::char_traits.
-// TODO(LLVM-19): Remove this class.
-//
-#if !defined(_LIBCPP_CHAR_TRAITS_REMOVE_BASE_SPECIALIZATION)
-template <class _CharT>
-struct _LIBCPP_DEPRECATED_(
-    "char_traits<T> for T not equal to char, wchar_t, char8_t, char16_t or char32_t is non-standard and is provided "
-    "for a temporary period. It will be removed in LLVM 19, so please migrate off of it.") char_traits {
-  using char_type  = _CharT;
-  using int_type   = int;
-  using off_type   = streamoff;
-  using pos_type   = streampos;
-  using state_type = mbstate_t;
-
-  static inline void _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI
-  assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {
-    __c1 = __c2;
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT {
-    return __c1 == __c2;
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT {
-    return __c1 < __c2;
-  }
-
-  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 int
-  compare(const char_type* __s1, const char_type* __s2, size_t __n) {
-    for (; __n; --__n, ++__s1, ++__s2) {
-      if (lt(*__s1, *__s2))
-        return -1;
-      if (lt(*__s2, *__s1))
-        return 1;
-    }
-    return 0;
-  }
-  _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX17 size_t length(const char_type* __s) {
-    size_t __len = 0;
-    for (; !eq(*__s, char_type(0)); ++__s)
-      ++__len;
-    return __len;
-  }
-  _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX17 const char_type*
-  find(const char_type* __s, size_t __n, const char_type& __a) {
-    for (; __n; --__n) {
-      if (eq(*__s, __a))
-        return __s;
-      ++__s;
-    }
-    return nullptr;
-  }
-  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 char_type*
-  move(char_type* __s1, const char_type* __s2, size_t __n) {
-    if (__n == 0)
-      return __s1;
-    char_type* __r = __s1;
-    if (__s1 < __s2) {
-      for (; __n; --__n, ++__s1, ++__s2)
-        assign(*__s1, *__s2);
-    } else if (__s2 < __s1) {
-      __s1 += __n;
-      __s2 += __n;
-      for (; __n; --__n)
-        assign(*--__s1, *--__s2);
-    }
-    return __r;
-  }
-  _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX20 char_type*
-  copy(char_type* __s1, const char_type* __s2, size_t __n) {
-    _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES(!std::__is_pointer_in_range(__s1, __s1 + __n, __s2),
-                                          "char_traits::copy: source and destination ranges overlap");
-    char_type* __r = __s1;
-    for (; __n; --__n, ++__s1, ++__s2)
-      assign(*__s1, *__s2);
-    return __r;
-  }
-  _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX20 char_type*
-  assign(char_type* __s, size_t __n, char_type __a) {
-    char_type* __r = __s;
-    for (; __n; --__n, ++__s)
-      assign(*__s, __a);
-    return __r;
-  }
-
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int_type not_eof(int_type __c) _NOEXCEPT {
-    return eq_int_type(__c, eof()) ? ~eof() : __c;
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT {
-    return char_type(__c);
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT {
-    return int_type(__c);
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT {
-    return __c1 == __c2;
-  }
-  static inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT { return int_type(EOF); }
-};
-#endif // !defined(_LIBCPP_CHAR_TRAITS_REMOVE_BASE_SPECIALIZATION)
-
 // char_traits<char>
 
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