[libc++] Removes _LIBCPP_AVAILABILITY_TO_CHARS.

[Mordante]

Summary

After moving the std::to_chars base 10 implementation from the dylib to
the header the integral overloads of std::to_chars are available on all
platforms.

Remove the _LIBCPP_AVAILABILITY_TO_CHARS availability macro and update
the tests.

Depends on D125704

[Mordante]

Seems backdeployment fails so it seems we need to keep the availability macros.

[ldionne]

In D125745#3519531, @Mordante wrote:

Seems backdeployment fails so it seems we need to keep the availability macros.

It looks to me like the only failure is an XPASS in libcxx/test/std/utilities/charconv/charconv.from.chars/integral.roundtrip.pass.cpp, where you seem to have forgotten to remove the XFAIL line. I think this patch should be revived!

[Mordante]

Applies @ldionne's suggestion to fix the CI.

[Mordante]

In D125745#3547648, @ldionne wrote:

In D125745#3519531, @Mordante wrote:

Seems backdeployment fails so it seems we need to keep the availability macros.

It looks to me like the only failure is an XPASS in libcxx/test/std/utilities/charconv/charconv.from.chars/integral.roundtrip.pass.cpp, where you seem to have forgotten to remove the XFAIL line. I think this patch should be revived!

Thanks good catch!

[ldionne]

LGTM.

Can we add a release note to mention that to_chars doesn't have a minimum deployment target anymore? It's something useful for folks to know.

libcxx/test/std/utilities/charconv/charconv.from.chars/integral.roundtrip.pass.cpp

12–13

This should be removed too!

[Mordante]

In D125745#3550768, @ldionne wrote:

LGTM.

Can we add a release note to mention that to_chars doesn't have a minimum deployment target anymore? It's something useful for folks to know.

Good point, I only wonder which section would be most appropriate "New features" or "ABI changes". WDYT?

[ldionne]

In D125745#3552500, @Mordante wrote:

In D125745#3550768, @ldionne wrote:

LGTM.

Can we add a release note to mention that to_chars doesn't have a minimum deployment target anymore? It's something useful for folks to know.

Good point, I only wonder which section would be most appropriate "New features" or "ABI changes". WDYT?

I would say "New features" because from the user's perspective, it allows them to use this new feature even if they had back-deployment requirements before.

libcxx/docs/ReleaseNotes.rst

- `pop_heap` now uses an algorithm known as "bottom-up heapsort" or
   elements using move-assignment instead of `swap`.
 
 - Libc++ now supports a variety of assertions that can be turned on to help catch
   undefined behavior in user code. This new support is now separate from the old
   (and incomplete) Debug Mode. Vendors can select whether the library they ship
   should include assertions or not by default. For details, see
   :ref:`the documentation <assertions-mode>` about this new feature.
 
+- The implementation of the function ``std::to_chars`` for integral types has
+  moved from the dylib to the header. This means the function no longer has a
+  minimum deployment target.
+
 API Changes
 -----------
 
 - The ``_LIBCPP_ABI_UNSTABLE`` macro has been removed in favour of setting
   ``_LIBCPP_ABI_VERSION=2``. This should not have any impact on users because
   they were not supposed to set ``_LIBCPP_ABI_UNSTABLE`` manually, however we
   still feel that it is worth mentioning in the release notes in case some users
   had been doing it.

libcxx/include/__availability

#   define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 
     // These macros control the availability of all parts of <filesystem> that
     // depend on something in the dylib.
 #   define _LIBCPP_AVAILABILITY_FILESYSTEM
 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH
 #   define _LIBCPP_AVAILABILITY_FILESYSTEM_POP
 // #   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
 
-    // This controls the availability of std::to_chars for integral arguments.
-#   define _LIBCPP_AVAILABILITY_TO_CHARS
-
     // This controls the availability of floating-point std::to_chars functions.
     // These overloads were added later than the integer overloads.
 #   define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT
 
     // This controls the availability of the C++20 synchronization library,
     // which requires shared library support for various operations
     // (see libcxx/src/atomic.cpp). This includes <barier>, <latch>,
     // <semaphore>, and notification functions on std::atomic.
#   define _LIBCPP_AVAILABILITY_FILESYSTEM_POP                                  \
         _Pragma("clang attribute pop")
 #   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) ||    \
         (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \
         (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) ||         \
         (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000)
 #       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
 #   endif
 
-#   define _LIBCPP_AVAILABILITY_TO_CHARS                                        \
-        _LIBCPP_AVAILABILITY_FILESYSTEM
-
 #   define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT                         \
         __attribute__((unavailable))
 
 #   define _LIBCPP_AVAILABILITY_SYNC                                            \
         __attribute__((availability(macos,strict,introduced=11.0)))             \
         __attribute__((availability(ios,strict,introduced=14.0)))               \
         __attribute__((availability(tvos,strict,introduced=14.0)))              \
         __attribute__((availability(watchos,strict,introduced=7.0)))

libcxx/include/charconv

struct _LIBCPP_HIDDEN __traits_base
     using type = uint64_t;
 
     static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
     {
         auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
         return __t - (__v < __table<>::__pow10_64[__t]) + 1;
     }
 
-    _LIBCPP_AVAILABILITY_TO_CHARS
     static _LIBCPP_HIDE_FROM_ABI char* __convert(_Tp __v, char* __p)
     {
         return __itoa::__base_10_u64(__v, __p);
     }
 
     static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_64)& __pow() { return __table<>::__pow10_64; }
 };
 
 template <typename _Tp>
 struct _LIBCPP_HIDDEN
     __traits_base<_Tp, decltype(void(uint32_t{declval<_Tp>()}))>
 {
     using type = uint32_t;
 
     static _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
     {
         auto __t = (32 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
         return __t - (__v < __table<>::__pow10_32[__t]) + 1;
     }
 
-    _LIBCPP_AVAILABILITY_TO_CHARS
     static _LIBCPP_HIDE_FROM_ABI char* __convert(_Tp __v, char* __p)
     {
         return __itoa::__base_10_u32(__v, __p);
     }
 
     static _LIBCPP_HIDE_FROM_ABI decltype(__table<>::__pow10_32)& __pow() { return __table<>::__pow10_32; }
 };
 

 inline _LIBCPP_HIDE_FROM_ABI _Tp
 __complement(_Tp __x)
 {
     static_assert(is_unsigned<_Tp>::value, "cast to unsigned first");
     return _Tp(~__x + 1);
 }
 
 template <typename _Tp>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_itoa(char* __first, char* __last, _Tp __value, true_type)
 {
     auto __x = __to_unsigned_like(__value);
     if (__value < 0 && __first != __last)
     {
         *__first++ = '-';
         __x = __complement(__x);
     }
 
     return __to_chars_itoa(__first, __last, __x, false_type());
 }
 
 template <typename _Tp>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_itoa(char* __first, char* __last, _Tp __value, false_type)
 {
     using __tx = __itoa::__traits<_Tp>;
     auto __diff = __last - __first;
 
     if (__tx::digits <= __diff || __tx::__width(__value) <= __diff)
         return {__tx::__convert(__value, __first), errc(0)};
     else
         return {__last, errc::value_too_large};
 }
 
 template <typename _Tp>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_integral(char* __first, char* __last, _Tp __value, int __base,
                     true_type)
 {
     auto __x = __to_unsigned_like(__value);
     if (__value < 0 && __first != __last)
     {
         *__first++ = '-';

 template <unsigned _Base, typename _Tp,
           typename enable_if<(sizeof(_Tp) < sizeof(unsigned)), int>::type = 0>
 _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_integral(char* __first, char* __last, _Tp __value) {
   return std::__to_chars_integral<_Base>(__first, __last, static_cast<unsigned>(__value));
 }
 
 template <typename _Tp>
-_LIBCPP_AVAILABILITY_TO_CHARS _LIBCPP_HIDE_FROM_ABI int
+_LIBCPP_HIDE_FROM_ABI int
 __to_chars_integral_width(_Tp __value, unsigned __base) {
   _LIBCPP_ASSERT(__value >= 0, "The function requires a non-negative value.");
 
   unsigned __base_2 = __base * __base;
   unsigned __base_3 = __base_2 * __base;
   unsigned __base_4 = __base_2 * __base_2;
 
   int __r = 0;
while (true) {
     __value /= __base_4;
     __r += 4;
   }
 
   __libcpp_unreachable();
 }
 
 template <typename _Tp>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 __to_chars_integral(char* __first, char* __last, _Tp __value, int __base,
                     false_type)
 {
   if (__base == 10) [[likely]]
     return __to_chars_itoa(__first, __last, __value, false_type());
 
   switch (__base) {
do {
     unsigned __c = __value % __base;
     __value /= __base;
     *--__p = "0123456789abcdefghijklmnopqrstuvwxyz"[__c];
   } while (__value != 0);
   return {__last, errc(0)};
 }
 
 template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 to_chars(char* __first, char* __last, _Tp __value)
 {
     return __to_chars_itoa(__first, __last, __value, is_signed<_Tp>());
 }
 
 template <typename _Tp, typename enable_if<is_integral<_Tp>::value, int>::type = 0>
-_LIBCPP_AVAILABILITY_TO_CHARS
 inline _LIBCPP_HIDE_FROM_ABI to_chars_result
 to_chars(char* __first, char* __last, _Tp __value, int __base)
 {
     _LIBCPP_ASSERT(2 <= __base && __base <= 36, "base not in [2, 36]");
     return __to_chars_integral(__first, __last, __value, __base,
                                is_signed<_Tp>());
 }
 

libcxx/test/libcxx/utilities/charconv/charconv.to.chars/availability.fail.cpp

-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// UNSUPPORTED: c++03
-// REQUIRES: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
-
-// Test the availability markup on std::to_chars.
-
-#include <charconv>
-
-int main(int, char**)
-{
-    char buf[100];
-    int int_value = 33;
-    long long_value = 33;
-    int base = 2;
-    std::to_chars(buf, buf + 100, int_value); // expected-error{{is unavailable: introduced in}}
-    std::to_chars(buf, buf + 100, int_value, base); // expected-error{{is unavailable: introduced in}}
-
-    std::to_chars(buf, buf + 100, long_value); // expected-error{{is unavailable: introduced in}}
-    std::to_chars(buf, buf + 100, long_value, base); // expected-error{{is unavailable: introduced in}}
-}

libcxx/test/std/utilities/charconv/charconv.from.chars/integral.roundtrip.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03
 // UNSUPPORTED: !stdlib=libc++ && c++11
 // UNSUPPORTED: !stdlib=libc++ && c++14
 
-// The roundtrip test uses to_chars, which requires functions in the dylib
-// that were introduced in Mac OS 10.15.
-//
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
-
 // <charconv>
 
 // from_chars_result from_chars(const char* first, const char* last,
 //                              Integral& value, int base = 10)
 
 #include <charconv>
 #include "test_macros.h"
 #include "charconv_test_helpers.h"
 

libcxx/test/std/utilities/charconv/charconv.to.chars/integral.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03
 // UNSUPPORTED: !stdlib=libc++ && c++11
 // UNSUPPORTED: !stdlib=libc++ && c++14
 
-// to_chars requires functions in the dylib that were introduced in Mac OS 10.15.
-//
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
-
 // <charconv>
 
 // to_chars_result to_chars(char* first, char* last, Integral value,
 //                          int base = 10)
 
 #include <charconv>
 #include "test_macros.h"
 #include "charconv_test_helpers.h"