[libc++] Enable the synchronization library on Apple platforms

[ldionne]

Summary

The synchronization library was marked as disabled on Apple platforms
up to now because we were not 100% sure that it was going to be ABI
stable. However, it's been some time since we shipped it in upstream
libc++ now and there's been no changes so far. This patch enables the
synchronization library on Apple platforms, and hence commits the ABI
stability as far as that vendor is concerned.

[ldionne]

Can you please confirm that you don't foresee any ABI changes?

[ldionne]

Ping @__simt__ @wash @Bigcheese Do we foresee any ABI changes? If not, we'd like to mark this as available on Apple platforms ASAP, because people have started seeing issues where codebases expect the synchronization library to be provided by AppleClang, but it's not. If we don't plan on making ABI breaking changes, I think it would be positive for the C++ ecosystem to ship it.

[ldionne]

Rebase onto main

[jfb]

I would recommend checking with @MadCoder about the implementation and ABI, since the kernel has Opinions on this. IIRC he looked at Olivier's original patch.

[ldionne]

In D96790#2734482, @jfb wrote:

I would recommend checking with @MadCoder about the implementation and ABI, since the kernel has Opinions on this. IIRC he looked at Olivier's original patch.

Yup. What I'm mostly concerned about though is the ABI between the libc++ dylib and its headers. But it looks like this isn't going to change, so I'm going to commit this now.

[ldionne]

Rebase onto main with the new triple-based availability.

libcxx/include/__availability

#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) ||    \
         (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
 
-    // Note: Those are not ABI-stable yet, so we can't ship them.
 #   define _LIBCPP_AVAILABILITY_SYNC                                            \
-        __attribute__((unavailable))
-#   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
-#   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
-#   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
-#   define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
+        __attribute__((availability(macosx,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)))
+#   if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) ||    \
+        (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \
+        (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) ||         \
+        (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000)
+#       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
+#       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
+#       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
+#       define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
+#   endif
 
 #else
 
 // ...New vendors can add availability markup here...
 
 #   error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!"
 
 #endif

libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.wait/atomic_wait.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: libcpp-has-no-threads
 // XFAIL: c++03
 // XFAIL: !non-lockfree-atomics
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.barrier/arrive.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.barrier/arrive_and_drop.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.barrier/arrive_and_wait.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.barrier/completion.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.latch/arrive_and_wait.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.latch/count_down.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.latch/try_wait.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.semaphore/acquire.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.semaphore/binary.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.semaphore/release.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.semaphore/timed.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9
 

libcxx/test/std/thread/thread.semaphore/try_acquire.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: libcpp-has-no-threads
 // UNSUPPORTED: c++03, c++11
 
-// This test requires the dylib support introduced in D68480,
-// which hasn't shipped yet.
-// XFAIL: with_system_cxx_lib=macosx
+// This test requires the dylib support introduced in D68480, which shipped in
+// macOS 11.0.
 // XFAIL: with_system_cxx_lib=macosx10.15
 // XFAIL: with_system_cxx_lib=macosx10.14
 // XFAIL: with_system_cxx_lib=macosx10.13
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
 // XFAIL: with_system_cxx_lib=macosx10.9