bpo-43568: Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3 (GH-25827)

Only complain if the config target is >= 10.3 and the current target is
< 10.3. The check was originally added to ensure that incompatible
LDSHARED flags are not used, because -undefined dynamic_lookup is
used when building for 10.3 and later, and is not supported on older OS
versions. Apart from that, there should be no problem in general
with using an older target.

Authored-by: Joshua Root <jmr@macports.org>

Lib/_osx_support.py

@@ -525,10 +525,10 @@ def get_platform_osx(_config_vars, osname, release, machine):
             try:
                 macrelease = tuple(int(i) for i in macrelease.split('.')[0:2])
             except ValueError:
-                macrelease = (10, 0)
+                macrelease = (10, 3)
         else:
             # assume no universal support
-            macrelease = (10, 0)
+            macrelease = (10, 3)
 
         if (macrelease >= (10, 4)) and '-arch' in cflags.strip():
             # The universal build will build fat binaries, but not on

Lib/distutils/spawn.py

@@ -59,13 +59,17 @@ def spawn(cmd, search_path=1, verbose=0, dry_run=0):
             if _cfg_target:
                 _cfg_target_split = [int(x) for x in _cfg_target.split('.')]
         if _cfg_target:
-            # ensure that the deployment target of build process is not less
-            # than that used when the interpreter was built. This ensures
-            # extension modules are built with correct compatibility values
+            # Ensure that the deployment target of the build process is not
+            # less than 10.3 if the interpreter was built for 10.3 or later.
+            # This ensures extension modules are built with correct
+            # compatibility values, specifically LDSHARED which can use
+            # '-undefined dynamic_lookup' which only works on >= 10.3.
             cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target)
-            if _cfg_target_split > [int(x) for x in cur_target.split('.')]:
+            cur_target_split = [int(x) for x in cur_target.split('.')]
+            if _cfg_target_split[:2] >= [10, 3] and cur_target_split[:2] < [10, 3]:
                 my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: '
-                          'now "%s" but "%s" during configure'
+                          'now "%s" but "%s" during configure;'
+                          'must use 10.3 or later'
                                 % (cur_target, _cfg_target))
                 raise DistutilsPlatformError(my_msg)
             env = dict(os.environ,

Lib/test/test_posix.py

@@ -1070,7 +1070,7 @@ class PosixTester(unittest.TestCase):
         # Issues 16698: OS X ABIs prior to 10.6 have limits on getgroups()
         if sys.platform == 'darwin':
             import sysconfig
-            dt = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET') or '10.0'
+            dt = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET') or '10.3'
             if tuple(int(n) for n in dt.split('.')[0:2]) < (10, 6):
                 raise unittest.SkipTest("getgroups(2) is broken prior to 10.6")
 

Misc/NEWS.d/next/macOS/2021-05-02-19-50-52.bpo-43568.AeLNBd.rst

@@ -0,0 +1 @@
+Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3

configure

@@ -9656,19 +9656,7 @@ then
 		   test ${dep_target_minor} -le 2
 		then
 			# building for OS X 10.0 through 10.2
-			LDSHARED='$(CC) -bundle'
-			LDCXXSHARED='$(CXX) -bundle'
-			if test "$enable_framework" ; then
-				# Link against the framework. All externals should be defined.
-				BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-				LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-				LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-			else
-				# No framework, use the Python app as bundle-loader
-				BLDSHARED="$LDSHARED "'-bundle_loader $(BUILDPYTHON)'
-				LDSHARED="$LDSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
-				LDCXXSHARED="$LDCXXSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
-			fi
+			as_fn_error $? "MACOSX_DEPLOYMENT_TARGET too old ($MACOSX_DEPLOYMENT_TARGET), only 10.3 or later is supported" "$LINENO" 5
 		else
 			# building for OS X 10.3 and later
 			LDSHARED='$(CC) -bundle -undefined dynamic_lookup'

configure.ac

@@ -2651,19 +2651,7 @@ then
 		   test ${dep_target_minor} -le 2
 		then
 			# building for OS X 10.0 through 10.2
-			LDSHARED='$(CC) -bundle'
-			LDCXXSHARED='$(CXX) -bundle'
-			if test "$enable_framework" ; then
-				# Link against the framework. All externals should be defined.
-				BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-				LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-				LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
-			else
-				# No framework, use the Python app as bundle-loader
-				BLDSHARED="$LDSHARED "'-bundle_loader $(BUILDPYTHON)'
-				LDSHARED="$LDSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
-				LDCXXSHARED="$LDCXXSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
-			fi
+			AC_MSG_ERROR([MACOSX_DEPLOYMENT_TARGET too old ($MACOSX_DEPLOYMENT_TARGET), only 10.3 or later is supported])
 		else
 			# building for OS X 10.3 and later
 			LDSHARED='$(CC) -bundle -undefined dynamic_lookup'