bpo-41100: Support macOS 11 and Apple Silicon (GH-22855)

Co-authored-by:  Lawrence D’Anna <lawrence_danna@apple.com>

* Add support for macOS 11 and Apple Silicon (aka arm64)
   
  As a side effect of this work use the system copy of libffi on macOS, and remove the vendored copy

* Support building on recent versions of macOS while deploying to older versions

  This allows building installers on macOS 11 while still supporting macOS 10.9.

9 files changed, 322 insertions, 14 deletions

diff --git a/Lib/_osx_support.py b/Lib/_osx_support.py
index e9efce7..8a696ee 100644
--- a/Lib/_osx_support.py
+++ b/Lib/_osx_support.py
@@ -110,6 +110,26 @@ def _get_system_version():
 
     return _SYSTEM_VERSION
 
+_SYSTEM_VERSION_TUPLE = None
+def _get_system_version_tuple():
+    """
+    Return the macOS system version as a tuple
+
+    The return value is safe to use to compare
+    two version numbers.
+    """
+    global _SYSTEM_VERSION_TUPLE
+    if _SYSTEM_VERSION_TUPLE is None:
+        osx_version = _get_system_version()
+        if osx_version:
+            try:
+                _SYSTEM_VERSION_TUPLE = tuple(int(i) for i in osx_version.split('.'))
+            except ValueError:
+                _SYSTEM_VERSION_TUPLE = ()
+
+    return _SYSTEM_VERSION_TUPLE
+   
+
 def _remove_original_values(_config_vars):
     """Remove original unmodified values for testing"""
     # This is needed for higher-level cross-platform tests of get_platform.
@@ -132,14 +152,18 @@ def _supports_universal_builds():
     # builds, in particular -isysroot and -arch arguments to the compiler. This
     # is in support of allowing 10.4 universal builds to run on 10.3.x systems.
 
-    osx_version = _get_system_version()
-    if osx_version:
-        try:
-            osx_version = tuple(int(i) for i in osx_version.split('.'))
-        except ValueError:
-            osx_version = ''
+    osx_version = _get_system_version_tuple()
     return bool(osx_version >= (10, 4)) if osx_version else False
 
+def _supports_arm64_builds():
+    """Returns True if arm64 builds are supported on this system"""
+    # There are two sets of systems supporting macOS/arm64 builds:
+    # 1. macOS 11 and later, unconditionally
+    # 2. macOS 10.15 with Xcode 12.2 or later
+    # For now the second category is ignored.
+    osx_version = _get_system_version_tuple()
+    return osx_version >= (11, 0) if osx_version else False
+
 
 def _find_appropriate_compiler(_config_vars):
     """Find appropriate C compiler for extension module builds"""
@@ -331,6 +355,12 @@ def compiler_fixup(compiler_so, cc_args):
             except ValueError:
                 break
 
+    elif not _supports_arm64_builds():
+        # Look for "-arch arm64" and drop that
+        for idx in range(len(compiler_so)):
+            if compiler_so[idx] == '-arch' and compiler_so[idx+1] == "arm64":
+                del compiler_so[idx:idx+2]
+
     if 'ARCHFLAGS' in os.environ and not stripArch:
         # User specified different -arch flags in the environ,
         # see also distutils.sysconfig
@@ -481,6 +511,8 @@ def get_platform_osx(_config_vars, osname, release, machine):
 
             if len(archs) == 1:
                 machine = archs[0]
+            elif archs == ('arm64', 'x86_64'):
+                machine = 'universal2'
             elif archs == ('i386', 'ppc'):
                 machine = 'fat'
             elif archs == ('i386', 'x86_64'):
diff --git a/Lib/ctypes/macholib/dyld.py b/Lib/ctypes/macholib/dyld.py
index 9d86b05..1c3f8fd 100644
--- a/Lib/ctypes/macholib/dyld.py
+++ b/Lib/ctypes/macholib/dyld.py
@@ -6,6 +6,11 @@ import os
 from ctypes.macholib.framework import framework_info
 from ctypes.macholib.dylib import dylib_info
 from itertools import *
+try:
+    from _ctypes import _dyld_shared_cache_contains_path
+except ImportError:
+    def _dyld_shared_cache_contains_path(*args):
+        raise NotImplementedError
 
 __all__ = [
     'dyld_find', 'framework_find',
@@ -122,8 +127,15 @@ def dyld_find(name, executable_path=None, env=None):
                 dyld_executable_path_search(name, executable_path),
                 dyld_default_search(name, env),
             ), env):
+
         if os.path.isfile(path):
             return path
+        try:
+            if _dyld_shared_cache_contains_path(path):
+                return path
+        except NotImplementedError:
+            pass
+
     raise ValueError("dylib %s could not be found" % (name,))
 
 def framework_find(fn, executable_path=None, env=None):
diff --git a/Lib/ctypes/test/test_macholib.py b/Lib/ctypes/test/test_macholib.py
index 6b35269..a1bac26 100644
--- a/Lib/ctypes/test/test_macholib.py
+++ b/Lib/ctypes/test/test_macholib.py
@@ -45,19 +45,22 @@ def find_lib(name):
 class MachOTest(unittest.TestCase):
     @unittest.skipUnless(sys.platform == "darwin", 'OSX-specific test')
     def test_find(self):
-
-        self.assertEqual(find_lib('pthread'),
-                             '/usr/lib/libSystem.B.dylib')
+        # On Mac OS 11, system dylibs are only present in the shared cache,
+        # so symlinks like libpthread.dylib -> libSystem.B.dylib will not
+        # be resolved by dyld_find
+        self.assertIn(find_lib('pthread'),
+                              ('/usr/lib/libSystem.B.dylib', '/usr/lib/libpthread.dylib'))
 
         result = find_lib('z')
         # Issue #21093: dyld default search path includes $HOME/lib and
         # /usr/local/lib before /usr/lib, which caused test failures if
         # a local copy of libz exists in one of them. Now ignore the head
         # of the path.
-        self.assertRegex(result, r".*/lib/libz\..*.*\.dylib")
+        self.assertRegex(result, r".*/lib/libz.*\.dylib")
 
-        self.assertEqual(find_lib('IOKit'),
-                             '/System/Library/Frameworks/IOKit.framework/Versions/A/IOKit')
+        self.assertIn(find_lib('IOKit'),
+                              ('/System/Library/Frameworks/IOKit.framework/Versions/A/IOKit',
+                              '/System/Library/Frameworks/IOKit.framework/IOKit'))
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/distutils/tests/test_build_ext.py b/Lib/distutils/tests/test_build_ext.py
index f9e0d76..6bb009a 100644
--- a/Lib/distutils/tests/test_build_ext.py
+++ b/Lib/distutils/tests/test_build_ext.py
@@ -493,7 +493,7 @@ class BuildExtTestCase(TempdirManager,
         # format the target value as defined in the Apple
         # Availability Macros.  We can't use the macro names since
         # at least one value we test with will not exist yet.
-        if target[1] < 10:
+        if target[:2] < (10, 10):
             # for 10.1 through 10.9.x -> "10n0"
             target = '%02d%01d0' % target
         else:
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index e61228d..d550abf 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -1036,6 +1036,7 @@ class BytesTest(BaseBytesTest, unittest.TestCase):
             c_char_p)
 
         PyBytes_FromFormat = pythonapi.PyBytes_FromFormat
+        PyBytes_FromFormat.argtypes = (c_char_p,)
         PyBytes_FromFormat.restype = py_object
 
         # basic tests
diff --git a/Lib/test/test_platform.py b/Lib/test/test_platform.py
index b5d21e5..9b6d93c 100644
--- a/Lib/test/test_platform.py
+++ b/Lib/test/test_platform.py
@@ -246,7 +246,7 @@ class PlatformTest(unittest.TestCase):
             self.assertEqual(res[1], ('', '', ''))
 
             if sys.byteorder == 'little':
-                self.assertIn(res[2], ('i386', 'x86_64'))
+                self.assertIn(res[2], ('i386', 'x86_64', 'arm64'))
             else:
                 self.assertEqual(res[2], 'PowerPC')
 
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index f57c882..a522717 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -1925,6 +1925,233 @@ class TestPosixSpawnP(unittest.TestCase, _PosixSpawnMixin):
         assert_python_ok(*args, PATH=path)
 
 
+@unittest.skipUnless(sys.platform == "darwin", "test weak linking on macOS")
+class TestPosixWeaklinking(unittest.TestCase):
+    # These test cases verify that weak linking support on macOS works
+    # as expected. These cases only test new behaviour introduced by weak linking,
+    # regular behaviour is tested by the normal test cases. 
+    #
+    # See the section on Weak Linking in Mac/README.txt for more information.
+    def setUp(self):
+        import sysconfig
+        import platform
+
+        config_vars = sysconfig.get_config_vars()
+        self.available = { nm for nm in config_vars if nm.startswith("HAVE_") and config_vars[nm] }
+        self.mac_ver = tuple(int(part) for part in platform.mac_ver()[0].split("."))
+
+    def _verify_available(self, name):
+        if name not in self.available:
+            raise unittest.SkipTest(f"{name} not weak-linked")
+
+    def test_pwritev(self):
+        self._verify_available("HAVE_PWRITEV")
+        if self.mac_ver >= (10, 16):
+            self.assertTrue(hasattr(os, "pwritev"), "os.pwritev is not available")
+            self.assertTrue(hasattr(os, "preadv"), "os.readv is not available")
+
+        else:
+            self.assertFalse(hasattr(os, "pwritev"), "os.pwritev is available")
+            self.assertFalse(hasattr(os, "preadv"), "os.readv is available")
+
+    def test_stat(self):
+        self._verify_available("HAVE_FSTATAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_FSTATAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FSTATAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.stat("file", dir_fd=0)
+
+    def test_access(self):
+        self._verify_available("HAVE_FACCESSAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_FACCESSAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FACCESSAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.access("file", os.R_OK, dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "follow_symlinks unavailable"):
+                os.access("file", os.R_OK, follow_symlinks=False)
+
+            with self.assertRaisesRegex(NotImplementedError, "effective_ids unavailable"):
+                os.access("file", os.R_OK, effective_ids=True)
+
+    def test_chmod(self):
+        self._verify_available("HAVE_FCHMODAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_FCHMODAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FCHMODAT", posix._have_functions)
+            self.assertIn("HAVE_LCHMOD", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.chmod("file", 0o644, dir_fd=0)
+
+    def test_chown(self):
+        self._verify_available("HAVE_FCHOWNAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_FCHOWNAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FCHOWNAT", posix._have_functions)
+            self.assertIn("HAVE_LCHOWN", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.chown("file", 0, 0, dir_fd=0)
+
+    def test_link(self):
+        self._verify_available("HAVE_LINKAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_LINKAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_LINKAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd unavailable"):
+                os.link("source", "target",  src_dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "dst_dir_fd unavailable"):
+                os.link("source", "target",  dst_dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd unavailable"):
+                os.link("source", "target",  src_dir_fd=0, dst_dir_fd=0)
+
+            # issue 41355: !HAVE_LINKAT code path ignores the follow_symlinks flag
+            with os_helper.temp_dir() as base_path:
+                link_path = os.path.join(base_path, "link")
+                target_path = os.path.join(base_path, "target")
+                source_path = os.path.join(base_path, "source")
+
+                with open(source_path, "w") as fp:
+                    fp.write("data")
+
+                os.symlink("target", link_path)
+
+                # Calling os.link should fail in the link(2) call, and
+                # should not reject *follow_symlinks* (to match the
+                # behaviour you'd get when building on a platform without
+                # linkat)
+                with self.assertRaises(FileExistsError):
+                    os.link(source_path, link_path, follow_symlinks=True)
+
+                with self.assertRaises(FileExistsError):
+                    os.link(source_path, link_path, follow_symlinks=False)
+
+
+    def test_listdir_scandir(self):
+        self._verify_available("HAVE_FDOPENDIR")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_FDOPENDIR", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FDOPENDIR", posix._have_functions)
+
+            with self.assertRaisesRegex(TypeError, "listdir: path should be string, bytes, os.PathLike or None, not int"):
+                os.listdir(0)
+
+            with self.assertRaisesRegex(TypeError, "scandir: path should be string, bytes, os.PathLike or None, not int"):
+                os.scandir(0)
+
+    def test_mkdir(self):
+        self._verify_available("HAVE_MKDIRAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_MKDIRAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_MKDIRAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.mkdir("dir", dir_fd=0)
+
+    def test_rename_replace(self):
+        self._verify_available("HAVE_RENAMEAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_RENAMEAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_RENAMEAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd and dst_dir_fd unavailable"):
+                os.rename("a", "b", src_dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd and dst_dir_fd unavailable"):
+                os.rename("a", "b", dst_dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd and dst_dir_fd unavailable"):
+                os.replace("a", "b", src_dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "src_dir_fd and dst_dir_fd unavailable"):
+                os.replace("a", "b", dst_dir_fd=0)
+
+    def test_unlink_rmdir(self):
+        self._verify_available("HAVE_UNLINKAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_UNLINKAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_UNLINKAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.unlink("path", dir_fd=0)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.rmdir("path", dir_fd=0)
+
+    def test_open(self):
+        self._verify_available("HAVE_OPENAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_OPENAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_OPENAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.open("path", os.O_RDONLY, dir_fd=0)
+
+    def test_readlink(self):
+        self._verify_available("HAVE_READLINKAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_READLINKAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_READLINKAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.readlink("path",  dir_fd=0)
+
+    def test_symlink(self):
+        self._verify_available("HAVE_SYMLINKAT")
+        if self.mac_ver >= (10, 10):
+            self.assertIn("HAVE_SYMLINKAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_SYMLINKAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.symlink("a", "b",  dir_fd=0)
+
+    def test_utime(self):
+        self._verify_available("HAVE_FUTIMENS")
+        self._verify_available("HAVE_UTIMENSAT")
+        if self.mac_ver >= (10, 13):
+            self.assertIn("HAVE_FUTIMENS", posix._have_functions)
+            self.assertIn("HAVE_UTIMENSAT", posix._have_functions)
+
+        else:
+            self.assertNotIn("HAVE_FUTIMENS", posix._have_functions)
+            self.assertNotIn("HAVE_UTIMENSAT", posix._have_functions)
+
+            with self.assertRaisesRegex(NotImplementedError, "dir_fd unavailable"):
+                os.utime("path", dir_fd=0)
+
+
 def test_main():
     try:
         support.run_unittest(
@@ -1932,6 +2159,7 @@ def test_main():
             PosixGroupsTester,
             TestPosixSpawn,
             TestPosixSpawnP,
+            TestPosixWeaklinking
         )
     finally:
         support.reap_children()
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index 6ced047..3258298 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -1041,6 +1041,36 @@ class TestOldPyTime(CPyTimeTestCase, unittest.TestCase):
             with self.assertRaises(ValueError):
                 pytime_object_to_timespec(float('nan'), time_rnd)
 
+@unittest.skipUnless(sys.platform == "darwin", "test weak linking on macOS")
+class TestTimeWeaklinking(unittest.TestCase):
+    # These test cases verify that weak linking support on macOS works
+    # as expected. These cases only test new behaviour introduced by weak linking,
+    # regular behaviour is tested by the normal test cases.
+    #
+    # See the section on Weak Linking in Mac/README.txt for more information.
+    def test_clock_functions(self):
+        import sysconfig
+        import platform
+
+        config_vars = sysconfig.get_config_vars()
+        var_name = "HAVE_CLOCK_GETTIME"
+        if var_name not in config_vars or not config_vars[var_name]:
+            raise unittest.SkipTest(f"{var_name} is not available")
+
+        mac_ver = tuple(int(x) for x in platform.mac_ver()[0].split("."))
+
+        clock_names = [
+            "CLOCK_MONOTONIC", "clock_gettime", "clock_gettime_ns", "clock_settime",
+            "clock_settime_ns", "clock_getres"]
+        
+        if mac_ver >= (10, 12):
+            for name in clock_names:
+                self.assertTrue(hasattr(time, name), f"time.{name} is not available")
+
+        else:
+            for name in clock_names:
+                self.assertFalse(hasattr(time, name), f"time.{name} is available")
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 90b0965..4f5636e 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -2516,11 +2516,13 @@ class CAPITest(unittest.TestCase):
     def test_from_format(self):
         import_helper.import_module('ctypes')
         from ctypes import (
+            c_char_p,
             pythonapi, py_object, sizeof,
             c_int, c_long, c_longlong, c_ssize_t,
             c_uint, c_ulong, c_ulonglong, c_size_t, c_void_p)
         name = "PyUnicode_FromFormat"
         _PyUnicode_FromFormat = getattr(pythonapi, name)
+        _PyUnicode_FromFormat.argtypes = (c_char_p,)
         _PyUnicode_FromFormat.restype = py_object
 
         def PyUnicode_FromFormat(format, *args):