ctypes: Disable checks for union types being passed by value

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1794572
Fixed upstream: https://bugs.python.org/issue16575

00339-bpo-16575.patch

@@ -0,0 +1,79 @@
+From 812479ed6c2c7854f5fafb2366d005845bfff67a Mon Sep 17 00:00:00 2001
+From: "Miss Islington (bot)"
+ <31488909+miss-islington@users.noreply.github.com>
+Date: Sun, 12 Jan 2020 03:41:07 -0800
+Subject: [PATCH] 00339: bpo-16575: Disabled checks for union types being
+ passed by value
+
+Although the underlying libffi issue remains open, adding these
+checks have caused problems in third-party projects which are in
+widespread use. See the issue for examples.
+
+The corresponding tests have also been skipped.
+
+(cherry picked from commit c12440c371025bea9c3bfb94945f006c486c2c01)
+---
+ Lib/ctypes/test/test_structures.py |  3 ++-
+ Modules/_ctypes/_ctypes.c          | 18 ++++++++++++++++++
+ 2 files changed, 20 insertions(+), 1 deletion(-)
+
+diff --git a/Lib/ctypes/test/test_structures.py b/Lib/ctypes/test/test_structures.py
+index 19c4430bea..cdbaa7fbd6 100644
+--- a/Lib/ctypes/test/test_structures.py
++++ b/Lib/ctypes/test/test_structures.py
+@@ -571,6 +571,7 @@ class StructureTestCase(unittest.TestCase):
+             self.assertEqual(f2, [0x4567, 0x0123, 0xcdef, 0x89ab,
+                                   0x3210, 0x7654, 0xba98, 0xfedc])
+ 
++    @unittest.skipIf(True, 'Test disabled for now - see bpo-16575/bpo-16576')
+     def test_union_by_value(self):
+         # See bpo-16575
+ 
+@@ -651,7 +652,7 @@ class StructureTestCase(unittest.TestCase):
+         self.assertEqual(test5.nested.an_int, 0)
+         self.assertEqual(test5.another_int, 0)
+ 
+-    #@unittest.skipIf('s390' in MACHINE, 'Test causes segfault on S390')
++    @unittest.skipIf(True, 'Test disabled for now - see bpo-16575/bpo-16576')
+     def test_bitfield_by_value(self):
+         # See bpo-16576
+ 
+diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
+index 347a3656b6..b51fcde364 100644
+--- a/Modules/_ctypes/_ctypes.c
++++ b/Modules/_ctypes/_ctypes.c
+@@ -2401,6 +2401,23 @@ converters_from_argtypes(PyObject *ob)
+     for (i = 0; i < nArgs; ++i) {
+         PyObject *cnv;
+         PyObject *tp = PyTuple_GET_ITEM(ob, i);
++/*
++ *      The following checks, relating to bpo-16575 and bpo-16576, have been
++ *      disabled. The reason is that, although there is a definite problem with
++ *      how libffi handles unions (https://github.com/libffi/libffi/issues/33),
++ *      there are numerous libraries which pass structures containing unions
++ *      by values - especially on Windows but examples also exist on Linux
++ *      (https://bugs.python.org/msg359834).
++ *
++ *      It may not be possible to get proper support for unions and bitfields
++ *      until support is forthcoming in libffi, but for now, adding the checks
++ *      has caused problems in otherwise-working software, which suggests it
++ *      is better to disable the checks.
++ *
++ *      Although specific examples reported relate specifically to unions and
++ *      not bitfields, the bitfields check is also being disabled as a
++ *      precaution.
++
+         StgDictObject *stgdict = PyType_stgdict(tp);
+ 
+         if (stgdict != NULL) {
+@@ -2428,6 +2445,7 @@ converters_from_argtypes(PyObject *ob)
+                 return NULL;
+             }
+         }
++ */
+ 
+         if (_PyObject_LookupAttrId(tp, &PyId_from_param, &cnv) <= 0) {
+             Py_DECREF(converters);
+-- 
+2.24.1
+

python3.spec

@@ -278,6 +278,15 @@ Patch274: 00274-fix-arch-names.patch
 # Ideally, we should talk to upstream and explain why we don't want this
 Patch328: 00328-pyc-timestamp-invalidation-mode.patch
 
+# 00339 #
+# Disabled checks for union types being passed by value
+# Although the underlying libffi issue remains open, adding these
+# checks have caused problems in third-party projects which are in
+# widespread use. See the issue for examples.
+# Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1794572
+# Fixed upstream: https://bugs.python.org/issue16575
+Patch339: 00339-bpo-16575.patch
+
 # (New patches go here ^^^)
 #
 # When adding new patches to "python" and "python3" in Fedora, EL, etc.,
@@ -625,6 +634,7 @@ rm Lib/ensurepip/_bundled/*.whl
 %patch251 -p1
 %patch274 -p1
 %patch328 -p1
+%patch339 -p1
 
 
 # Remove files that should be generated by the build
@@ -1569,8 +1579,9 @@ CheckPython optimized
 # ======================================================
 
 %changelog
-* Thu Jan 30 2020 Fedora Release Engineering <releng@fedoraproject.org> - 3.8.1-2
+* Thu Jan 30 2020 Miro Hrončok <mhroncok@redhat.com> - 3.8.1-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild
+- ctypes: Disable checks for union types being passed by value (#1794572)
 
 * Thu Dec 19 2019 Miro Hrončok <mhroncok@redhat.com> - 3.8.1-1
 - Update to Python 3.8.1