Changes due to review by Victor Stinner

python · ronaldoussoren · Nov 8, 2020 · Jul 20, 2020 · Jul 20, 2020 · Jul 20, 2020
commit fef2e93a846b12cf01d625c5c32d07e33b03e907
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
@@ -1909,7 +1909,9 @@ def test_posix_spawnp(self):
 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.
+    # 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
@@ -2027,9 +2029,6 @@ def test_link(self):
             finally:
                 support.rmtree(base_path)
 
-
-
-
     def test_listdir_scandir(self):
         self._verify_available("HAVE_FDOPENDIR")
         if self.mac_ver >= (10, 10):
@@ -2139,10 +2138,6 @@ def test_utime(self):
             with self.assertRaisesRegex(NotImplementedError, "follow_symlinks unavailable"):
                 os.utime("path", follow_symlinks=False)
 
-            # XXX: Check if this test is correct, the implementation of os.utime
-            #      is fairly complicated
-
-
 
 def test_main():
     try:

diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
@@ -1046,24 +1046,25 @@ 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.
-    def setUp(self):
+    #
+    # 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()
-        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("."))
+        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")
 
-    def _verify_available(self, name):
-        if name not in self.available:
-            raise unittest.SkipTest(f"{name} not weak-linked")
+        mac_ver = tuple(int(x) for x in platform.mac_ver()[0].split("."))
 
-    def test_clock_functions(self):
-        self._verify_available("HAVE_CLOCK_GETTIME")
         clock_names = [
             "CLOCK_MONOTONIC", "clock_gettime", "clock_gettime_ns", "clock_settime",
             "clock_settime_ns", "clock_getres"]
-        if self.mac_ver >= (10, 12):
+
+
+        if mac_ver >= (10, 12):
             for name in clock_names:
                 self.assertTrue(hasattr(time, name), f"time.{name} is not available")
 

diff --git a/Mac/README.rst b/Mac/README.rst
@@ -120,6 +120,8 @@ support ppc (Xcode 4 on 10.6 and later systems).  The flavor can be specified
 using the configure option ``--with-universal-archs=VALUE``. The following
 values are available:
 
+  * ``universal2``: ``arm64``, ``x86_64``
+
   * ``intel``:	  ``i386``, ``x86_64``
 
   * ``intel-32``: ``i386``
@@ -155,6 +157,8 @@ following combinations of SDKs and universal-archs flavors are available:
 
   * 10.15 and later SDKs support ``intel-64`` only
 
+  * 11.0 and later SDKs support ``universal2``
+
 The makefile for a framework build will also install ``python3.x-32``
 binaries when the universal architecture includes at least one 32-bit
 architecture (that is, for all flavors but ``64-bit`` and ``intel-64``).
@@ -352,6 +356,39 @@ A framework install also installs some applications in ``/Applications/Python X.
 And lastly a framework installation installs files in ``/usr/local/bin``, all of
 them symbolic links to files in ``/Library/Frameworks/Python.framework/Versions/X.Y/bin``.
 
+Weak linking support
+====================
+
+The CPython sources support building with the latest SDK while targetting deployment
+to macOS 10.9. This is done through weak linking of symbols introduced in macOS
+10.10 or later and checking for their availability at runtime.
+
+This requires the use of Apple's compiler toolchain on macOS 10.13 or later.
+
+The basic implementation pattern is:
+
+* ``HAVE_<FUNCTION>`` is a macro defined (or not) by the configure script
+
+* ``HAVE_<FUNCTION>_RUNTIME`` is a macro defined in the relevant source
+  files. This expands to a call to ``__builtin_available`` when using
+  a new enough Apple compiler, and to a true value otherwise.
+
+* Use ``HAVE_<FUNCTION>_RUNTIME`` before calling ``<function>``. This macro
+  *must* be used a the sole expression in an if statement::
+
+   if (HAVE_<FUNCTION>_RUNTIME) {
+     /* <function> is available */
+   }
+
+  Or:
+
+   if (HAVE_<FUNCTION>_RUNTIME) {} else {
+     /* <function> is not available */
+   }
+
+  Using other patterns (such as ``!HAVE_<FUNCTION>_RUNTIME``) is not supported
+  by Apple's compilers.
+
 
 Resources
 =========