[libc++] Remove availability annotations which can never be triggered (#69226)

According to https://developer.apple.com/support/xcode/, quite a few of
our availability macros don't do anything anymore, so we might as well
remove them to clean up the code a bit.

Author: philnik777

libcxx/docs/ReleaseNotes/18.rst

@@ -72,6 +72,11 @@ Improvements and New Features
 Deprecations and Removals
 -------------------------
 
+- Availability macros which will never trigger an error have been removed. This includes anything that has been
+  introduced before macOS 10.13, iOS 12, tvOS 12 and watchOS 4. This shouldn't affect anybody, since AppleClang 15
+  doesn't support any older OSes. If you are a vendor and make use of these macros, please inform the libc++ team so we
+  can re-introduce them and consider upstreaming support for your platform.
+
 - The non-conforming constructor ``std::future_error(std::error_code)`` has been removed. Please use the
   ``std::future_error(std::future_errc)`` constructor provided in C++17 instead.
 

libcxx/docs/index.rst

@@ -127,7 +127,7 @@ Libc++ also supports common platforms and architectures:
 =============== ========================= ============================
 Target platform Target architecture       Notes
 =============== ========================= ============================
-macOS 10.9+     i386, x86_64, arm64       Building the shared library itself requires targetting macOS 10.13+
+macOS 10.13+    i386, x86_64, arm64
 FreeBSD 12+     i386, x86_64, arm
 Linux           i386, x86_64, arm, arm64  Only glibc-2.24 and later and no other libc is officially supported
 Android 5.0+    i386, x86_64, arm, arm64

libcxx/include/__availability

@@ -87,11 +87,6 @@
 
 #if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
 
-    // This controls the availability of std::shared_mutex and std::shared_timed_mutex,
-    // which were added to the dylib later.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_SHARED_MUTEX
-#   define _LIBCPP_AVAILABILITY_SHARED_MUTEX
-
     // These macros control the availability of std::bad_optional_access and
     // other exception types. These were put in the shared library to prevent
     // code bloat from every user program defining the vtable for these exception
@@ -109,41 +104,6 @@
 // #   define _LIBCPP_AVAILABILITY_HAS_NO_BAD_ANY_CAST
 #   define _LIBCPP_AVAILABILITY_BAD_ANY_CAST
 
-    // This controls the availability of std::uncaught_exceptions().
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_UNCAUGHT_EXCEPTIONS
-#   define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS
-
-    // This controls the availability of the sized version of ::operator delete,
-    // ::operator delete[], and their align_val_t variants, which were all added
-    // in C++17, and hence not present in early dylibs.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_SIZED_NEW_DELETE
-#   define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE
-
-    // This controls the availability of the std::future_error exception.
-    //
-    // Note that when exceptions are disabled, the methods that normally throw
-    // std::future_error can be used even on older deployment targets, but those
-    // methods will abort instead of throwing.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_FUTURE_ERROR
-#   define _LIBCPP_AVAILABILITY_FUTURE_ERROR
-
-    // This controls the availability of std::type_info's vtable.
-    // I can't imagine how using std::type_info can work at all if
-    // this isn't supported.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_TYPEINFO_VTABLE
-#   define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
-
-    // This controls the availability of std::locale::category members
-    // (e.g. std::locale::collate), which are defined in the dylib.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_LOCALE_CATEGORY
-#   define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY
-
-    // This controls the availability of atomic operations on std::shared_ptr
-    // (e.g. `std::atomic_store(std::shared_ptr)`), which require a shared
-    // lock table located in the dylib.
-// #   define _LIBCPP_AVAILABILITY_HAS_NO_ATOMIC_SHARED_PTR
-#   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_HAS_NO_FILESYSTEM_LIBRARY
@@ -192,100 +152,14 @@
 
 #elif defined(__APPLE__)
 
-    // shared_mutex and shared_timed_mutex
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
-        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) ||         \
-        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_SHARED_MUTEX
-#   endif
-#   define _LIBCPP_AVAILABILITY_SHARED_MUTEX                                    \
-        __attribute__((availability(macos,strict,introduced=10.12)))            \
-        __attribute__((availability(ios,strict,introduced=10.0)))               \
-        __attribute__((availability(tvos,strict,introduced=10.0)))              \
-        __attribute__((availability(watchos,strict,introduced=3.0)))
-
-        // bad_optional_access, bad_variant_access and bad_any_cast
-        // Note: bad_optional_access & friends were not introduced in the matching
-        // macOS and iOS versions, so the version mismatch between macOS and others
-        // is intended.
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101300) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 120000) || \
-        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 120000) ||         \
-        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 50000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_BAD_OPTIONAL_ACCESS
-#       define _LIBCPP_AVAILABILITY_HAS_NO_BAD_VARIANT_ACCESS
-#       define _LIBCPP_AVAILABILITY_HAS_NO_BAD_ANY_CAST
-#   endif
-#   define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS                             \
-        __attribute__((availability(macos,strict,introduced=10.13)))            \
-        __attribute__((availability(ios,strict,introduced=12.0)))               \
-        __attribute__((availability(tvos,strict,introduced=12.0)))              \
-        __attribute__((availability(watchos,strict,introduced=5.0)))
-#   define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS                              \
-        _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
-#   define _LIBCPP_AVAILABILITY_BAD_ANY_CAST                                    \
-        _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
-
-    // uncaught_exceptions
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
-        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) ||         \
-        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_UNCAUGHT_EXCEPTIONS
-#   endif
-#   define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS                             \
-        __attribute__((availability(macos,strict,introduced=10.12)))            \
-        __attribute__((availability(ios,strict,introduced=10.0)))               \
-        __attribute__((availability(tvos,strict,introduced=10.0)))              \
-        __attribute__((availability(watchos,strict,introduced=3.0)))
-
-    // sized operator new and sized operator delete
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
-        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) ||         \
-        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_SIZED_NEW_DELETE
-#   endif
-#   define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE                                \
-        __attribute__((availability(macos,strict,introduced=10.12)))            \
-        __attribute__((availability(ios,strict,introduced=10.0)))               \
-        __attribute__((availability(tvos,strict,introduced=10.0)))              \
-        __attribute__((availability(watchos,strict,introduced=3.0)))
-
-    // future_error
-#   if (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 60000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_FUTURE_ERROR
-#   endif
-#   define _LIBCPP_AVAILABILITY_FUTURE_ERROR                                    \
-        __attribute__((availability(ios,strict,introduced=6.0)))
-
-    // type_info's vtable
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 100900) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 70000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_TYPEINFO_VTABLE
-#   endif
-#   define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE                                 \
-        __attribute__((availability(macos,strict,introduced=10.9)))             \
-        __attribute__((availability(ios,strict,introduced=7.0)))
-
-    // locale::category
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 100900) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 70000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_LOCALE_CATEGORY
-#   endif
-#   define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY                                 \
-        __attribute__((availability(macos,strict,introduced=10.9)))             \
-        __attribute__((availability(ios,strict,introduced=7.0)))
-
-    // atomic operations on shared_ptr
-#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 100900) ||    \
-        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 70000)
-#       define _LIBCPP_AVAILABILITY_HAS_NO_ATOMIC_SHARED_PTR
-#   endif
-#   define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR                               \
-        __attribute__((availability(macos,strict,introduced=10.9)))             \
-        __attribute__((availability(ios,strict,introduced=7.0)))
+#  if (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 50000)
+#    define _LIBCPP_AVAILABILITY_HAS_NO_BAD_OPTIONAL_ACCESS
+#    define _LIBCPP_AVAILABILITY_HAS_NO_BAD_VARIANT_ACCESS
+#    define _LIBCPP_AVAILABILITY_HAS_NO_BAD_ANY_CAST
+#  endif
+#  define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((availability(watchos,strict,introduced=5.0)))
+#  define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
+#  define _LIBCPP_AVAILABILITY_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
 
     // <filesystem>
 #   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) ||    \
@@ -385,12 +259,10 @@
 // Those are defined in terms of the availability attributes above, and
 // should not be vendor-specific.
 #if defined(_LIBCPP_HAS_NO_EXCEPTIONS)
-#   define _LIBCPP_AVAILABILITY_FUTURE
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
 #else
-#   define _LIBCPP_AVAILABILITY_FUTURE                    _LIBCPP_AVAILABILITY_FUTURE_ERROR
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST        _LIBCPP_AVAILABILITY_BAD_ANY_CAST
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
 #   define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS  _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS

libcxx/include/__exception/operations.h

@@ -31,7 +31,7 @@ _LIBCPP_EXPORTED_FROM_ABI terminate_handler set_terminate(terminate_handler) _NO
 _LIBCPP_EXPORTED_FROM_ABI terminate_handler get_terminate() _NOEXCEPT;
 
 _LIBCPP_EXPORTED_FROM_ABI bool uncaught_exception() _NOEXCEPT;
-_LIBCPP_EXPORTED_FROM_ABI _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS int uncaught_exceptions() _NOEXCEPT;
+_LIBCPP_EXPORTED_FROM_ABI int uncaught_exceptions() _NOEXCEPT;
 
 class _LIBCPP_EXPORTED_FROM_ABI exception_ptr;
 

libcxx/include/__locale

@@ -78,7 +78,7 @@ public:
     class _LIBCPP_EXPORTED_FROM_ABI id;
 
     typedef int category;
-    _LIBCPP_AVAILABILITY_LOCALE_CATEGORY
+
     static const category // values assigned here are for exposition only
         none     = 0,
         collate  = LC_COLLATE_MASK,

libcxx/include/__memory/shared_ptr.h

@@ -1985,8 +1985,7 @@ class _LIBCPP_EXPORTED_FROM_ABI __sp_mut
     friend _LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
 };
 
-_LIBCPP_EXPORTED_FROM_ABI _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-__sp_mut& __get_sp_mut(const void*);
+_LIBCPP_EXPORTED_FROM_ABI __sp_mut& __get_sp_mut(const void*);
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
@@ -1997,7 +1996,6 @@ atomic_is_lock_free(const shared_ptr<_Tp>*)
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
 atomic_load(const shared_ptr<_Tp>* __p)
 {
@@ -2010,15 +2008,13 @@ atomic_load(const shared_ptr<_Tp>* __p)
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 shared_ptr<_Tp>
 atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
 {
     return std::atomic_load(__p);
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 _LIBCPP_HIDE_FROM_ABI void
 atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 {
@@ -2030,15 +2026,13 @@ atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 void
 atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
 {
     std::atomic_store(__p, __r);
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
 atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 {
@@ -2051,15 +2045,13 @@ atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 shared_ptr<_Tp>
 atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
 {
     return std::atomic_exchange(__p, __r);
 }
 
 template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 _LIBCPP_HIDE_FROM_ABI bool
 atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
 {
@@ -2081,7 +2073,6 @@ atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, share
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 bool
 atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
 {
@@ -2090,7 +2081,6 @@ atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 bool
 atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
                                         shared_ptr<_Tp> __w, memory_order, memory_order)
@@ -2100,7 +2090,6 @@ atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* _
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 bool
 atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
                                       shared_ptr<_Tp> __w, memory_order, memory_order)

libcxx/include/__utility/small_buffer.h

@@ -62,7 +62,7 @@ class __small_buffer {
   }
 
   template <class _Stored>
-  _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE _LIBCPP_HIDE_FROM_ABI _Stored* __alloc() {
+  _LIBCPP_HIDE_FROM_ABI _Stored* __alloc() {
     if constexpr (__fits_in_buffer<_Stored>) {
       return std::launder(reinterpret_cast<_Stored*>(__buffer_));
     } else {
@@ -73,13 +73,13 @@ class __small_buffer {
   }
 
   template <class _Stored>
-  _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE _LIBCPP_HIDE_FROM_ABI void __dealloc() noexcept {
+  _LIBCPP_HIDE_FROM_ABI void __dealloc() noexcept {
     if constexpr (!__fits_in_buffer<_Stored>)
       ::operator delete[](*reinterpret_cast<void**>(__buffer_), sizeof(_Stored), align_val_t{alignof(_Stored)});
   }
 
   template <class _Stored, class... _Args>
-  _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE _LIBCPP_HIDE_FROM_ABI void __construct(_Args&&... __args) {
+  _LIBCPP_HIDE_FROM_ABI void __construct(_Args&&... __args) {
     _Stored* __buffer = __alloc<_Stored>();
     auto __guard      = std::__make_exception_guard([&] { __dealloc<_Stored>(); });
     std::construct_at(__buffer, std::forward<_Args>(__args)...);