From 8e1d89cbb4a9b777a5b2075d6ae521ec03b591bb Mon Sep 17 00:00:00 2001
From: Joshua Root <jmr@macports.org>
Date: Sun, 9 May 2021 10:53:48 +1000
Subject: [PATCH 1/2] bpo-43568: Relax distutils MACOSX_DEPLOYMENT_TARGET check
 (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. In particular, this allows targeting macOS
11.0 when Python was built for a newer minor version like 11.3.

(manually cherry picked from part of commit 8703178)
---
 Lib/distutils/spawn.py | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/Lib/distutils/spawn.py b/Lib/distutils/spawn.py
index 0d1bd0391e6f11..31df3f7faca552 100644
--- a/Lib/distutils/spawn.py
+++ b/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,

From 0f251dddeab215b4b392342dd3fa46010fe713a3 Mon Sep 17 00:00:00 2001
From: Ned Deily <nad@python.org>
Date: Wed, 2 Jun 2021 19:23:38 -0400
Subject: [PATCH 2/2] Add NEWS blurb.

---
 Misc/NEWS.d/next/macOS/2021-06-02-19-21-13.bpo-43568.viomLm.rst | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/macOS/2021-06-02-19-21-13.bpo-43568.viomLm.rst

diff --git a/Misc/NEWS.d/next/macOS/2021-06-02-19-21-13.bpo-43568.viomLm.rst b/Misc/NEWS.d/next/macOS/2021-06-02-19-21-13.bpo-43568.viomLm.rst
new file mode 100644
index 00000000000000..57757ba1ed0509
--- /dev/null
+++ b/Misc/NEWS.d/next/macOS/2021-06-02-19-21-13.bpo-43568.viomLm.rst
@@ -0,0 +1,2 @@
+Relax unnecessarily restrictive MACOSX_DEPLOYMENT_TARGET check when building
+extension modules for macOS. Patch by Joshua Root.