diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst index 83dade3bf2f01..14647a565d9ec 100644 --- a/libcxx/docs/ReleaseNotes/18.rst +++ b/libcxx/docs/ReleaseNotes/18.rst @@ -85,14 +85,6 @@ Deprecations and Removals warning). ``_LIBCPP_ENABLE_ASSERTIONS`` will be removed entirely in the next release and setting it will become an error. See :ref:`the hardening documentation ` for more details. -- The base template for ``std::char_traits`` has been removed. 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 no longer work. 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 previously cause unexpected - behavior while going undetected. - Upcoming Deprecations and Removals ---------------------------------- @@ -109,6 +101,17 @@ LLVM 18 and ```` will be removed in LLVM 18, as all their contents will have been implemented in namespace ``std`` for at least two releases. +LLVM 19 +~~~~~~~ + +- The base template for ``std::char_traits`` has been marked as deprecated and will be 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 when we + remove the base template. 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 while going undetected. + Note that the ``_LIBCPP_CHAR_TRAITS_REMOVE_BASE_SPECIALIZATION`` macro can be defined in LLVM 18 to eagerly remove + the specialization and prepare code bases for the unconditional removal in LLVM 19. + ABI Affecting Changes --------------------- diff --git a/libcxx/include/__string/char_traits.h b/libcxx/include/__string/char_traits.h index baf2d2346a596..ca9867c39067d 100644 --- a/libcxx/include/__string/char_traits.h +++ b/libcxx/include/__string/char_traits.h @@ -71,6 +71,108 @@ 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 +struct _LIBCPP_DEPRECATED_("char_traits 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 18, 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_INLINE_VISIBILITY 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_INLINE_VISIBILITY 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_INLINE_VISIBILITY + static _LIBCPP_CONSTEXPR_SINCE_CXX20 + char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) { + if (!__libcpp_is_constant_evaluated()) { + _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES( + __s2 < __s1 || __s2 >= __s1 + __n, "char_traits::copy overlapped range"); + } + char_type* __r = __s1; + for (; __n; --__n, ++__s1, ++__s2) + assign(*__s1, *__s2); + return __r; + } + _LIBCPP_INLINE_VISIBILITY + 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 template <> diff --git a/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp new file mode 100644 index 0000000000000..ec6f34ef5462e --- /dev/null +++ b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp @@ -0,0 +1,21 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +// + +// template<> struct char_traits for arbitrary T + +// Make sure we issue deprecation warnings. + +#include + +void f() { + std::char_traits t1; (void)t1; // expected-warning{{'char_traits' is deprecated}} + std::char_traits t2; (void)t2; // expected-warning{{'char_traits' is deprecated}} + std::char_traits t3; (void)t3; // expected-warning{{'char_traits' is deprecated}} +} diff --git a/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.pass.cpp b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.pass.cpp new file mode 100644 index 0000000000000..c2de29d22b2fe --- /dev/null +++ b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.pass.cpp @@ -0,0 +1,146 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +// + +// template<> struct char_traits for arbitrary T + +// Non-standard but provided temporarily for users to migrate. + +// ADDITIONAL_COMPILE_FLAGS: -Wno-deprecated + +#include +#include +#include + +#include "test_macros.h" + +template +TEST_CONSTEXPR_CXX20 bool test() { + static_assert(std::is_same::char_type, Char>::value, ""); + static_assert(std::is_same::int_type, int>::value, ""); + static_assert(std::is_same::off_type, std::streamoff>::value, ""); + static_assert(std::is_same::pos_type, std::streampos>::value, ""); + static_assert(std::is_same::state_type, std::mbstate_t>::value, ""); + + assert(std::char_traits::to_int_type(Char('a')) == Char('a')); + assert(std::char_traits::to_int_type(Char('A')) == Char('A')); + assert(std::char_traits::to_int_type(0) == 0); + + assert(std::char_traits::to_char_type(Char('a')) == Char('a')); + assert(std::char_traits::to_char_type(Char('A')) == Char('A')); + assert(std::char_traits::to_char_type(0) == 0); + + assert(std::char_traits::eof() == EOF); + + assert(std::char_traits::not_eof(Char('a')) == Char('a')); + assert(std::char_traits::not_eof(Char('A')) == Char('A')); + assert(std::char_traits::not_eof(0) == 0); + assert(std::char_traits::not_eof(std::char_traits::eof()) != + std::char_traits::eof()); + + assert(std::char_traits::lt(Char('\0'), Char('A')) == (Char('\0') < Char('A'))); + assert(std::char_traits::lt(Char('A'), Char('\0')) == (Char('A') < Char('\0'))); + assert(std::char_traits::lt(Char('a'), Char('a')) == (Char('a') < Char('a'))); + assert(std::char_traits::lt(Char('A'), Char('a')) == (Char('A') < Char('a'))); + assert(std::char_traits::lt(Char('a'), Char('A')) == (Char('a') < Char('A'))); + + assert( std::char_traits::eq(Char('a'), Char('a'))); + assert(!std::char_traits::eq(Char('a'), Char('A'))); + + assert( std::char_traits::eq_int_type(Char('a'), Char('a'))); + assert(!std::char_traits::eq_int_type(Char('a'), Char('A'))); + assert(!std::char_traits::eq_int_type(std::char_traits::eof(), Char('A'))); + assert( std::char_traits::eq_int_type(std::char_traits::eof(), std::char_traits::eof())); + + { + Char s1[] = {1, 2, 3, 0}; + Char s2[] = {0}; + assert(std::char_traits::length(s1) == 3); + assert(std::char_traits::length(s2) == 0); + } + + { + Char s1[] = {1, 2, 3}; + assert(std::char_traits::find(s1, 3, Char(1)) == s1); + assert(std::char_traits::find(s1, 3, Char(2)) == s1+1); + assert(std::char_traits::find(s1, 3, Char(3)) == s1+2); + assert(std::char_traits::find(s1, 3, Char(4)) == 0); + assert(std::char_traits::find(s1, 3, Char(0)) == 0); + assert(std::char_traits::find(NULL, 0, Char(0)) == 0); + } + + { + Char s1[] = {1, 2, 3}; + Char s2[3] = {0}; + assert(std::char_traits::copy(s2, s1, 3) == s2); + assert(s2[0] == Char(1)); + assert(s2[1] == Char(2)); + assert(s2[2] == Char(3)); + assert(std::char_traits::copy(NULL, s1, 0) == NULL); + assert(std::char_traits::copy(s1, NULL, 0) == s1); + } + + { + Char s1[] = {1, 2, 3}; + assert(std::char_traits::move(s1, s1+1, 2) == s1); + assert(s1[0] == Char(2)); + assert(s1[1] == Char(3)); + assert(s1[2] == Char(3)); + s1[2] = Char(0); + assert(std::char_traits::move(s1+1, s1, 2) == s1+1); + assert(s1[0] == Char(2)); + assert(s1[1] == Char(2)); + assert(s1[2] == Char(3)); + assert(std::char_traits::move(NULL, s1, 0) == NULL); + assert(std::char_traits::move(s1, NULL, 0) == s1); + } + + { + Char s1[] = {0}; + assert(std::char_traits::compare(s1, s1, 0) == 0); + assert(std::char_traits::compare(NULL, NULL, 0) == 0); + + Char s2[] = {1, 0}; + Char s3[] = {2, 0}; + assert(std::char_traits::compare(s2, s2, 1) == 0); + assert(std::char_traits::compare(s2, s3, 1) < 0); + assert(std::char_traits::compare(s3, s2, 1) > 0); + } + + { + Char s2[3] = {0}; + assert(std::char_traits::assign(s2, 3, Char(5)) == s2); + assert(s2[0] == Char(5)); + assert(s2[1] == Char(5)); + assert(s2[2] == Char(5)); + assert(std::char_traits::assign(NULL, 0, Char(5)) == NULL); + } + + { + Char c = Char('\0'); + std::char_traits::assign(c, Char('a')); + assert(c == Char('a')); + } + + return true; +} + +int main(int, char**) { + test(); + test(); + test(); + +#if TEST_STD_VER > 17 + static_assert(test()); + static_assert(test()); + static_assert(test()); +#endif + + return 0; +}