From 87d8287865e5c9f137f6b5cf8c34c2c509eb5e9d Mon Sep 17 00:00:00 2001
From: Paul Ganssle <paul@ganssle.io>
Date: Thu, 13 Aug 2020 22:38:30 -0400
Subject: [PATCH] bpo-41025: Fix subclassing for zoneinfo.ZoneInfo (GH-20965)

Prior to this change, attempting to subclass the C implementation of
zoneinfo.ZoneInfo gave the following error:

    TypeError: unbound method ZoneInfo.__init_subclass__() needs an argument

https://bugs.python.org/issue41025
---
 Lib/test/test_zoneinfo/test_zoneinfo.py                       | 4 ++--
 .../next/Library/2020-06-18-10-34-59.bpo-41025.elf_nz.rst     | 2 ++
 Modules/_zoneinfo.c                                           | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2020-06-18-10-34-59.bpo-41025.elf_nz.rst

diff --git a/Lib/test/test_zoneinfo/test_zoneinfo.py b/Lib/test/test_zoneinfo/test_zoneinfo.py
index d16e0d2c331..a9375fd5585 100644
--- a/Lib/test/test_zoneinfo/test_zoneinfo.py
+++ b/Lib/test/test_zoneinfo/test_zoneinfo.py
@@ -463,7 +463,7 @@ class CZoneInfoDatetimeSubclassTest(DatetimeSubclassMixin, CZoneInfoTest):
     pass
 
 
-class ZoneInfoTestSubclass(ZoneInfoTest):
+class ZoneInfoSubclassTest(ZoneInfoTest):
     @classmethod
     def setUpClass(cls):
         super().setUpClass()
@@ -484,7 +484,7 @@ class ZoneInfoTestSubclass(ZoneInfoTest):
         self.assertIsInstance(sub_obj, self.klass)
 
 
-class CZoneInfoTestSubclass(ZoneInfoTest):
+class CZoneInfoSubclassTest(ZoneInfoSubclassTest):
     module = c_zoneinfo
 
 
diff --git a/Misc/NEWS.d/next/Library/2020-06-18-10-34-59.bpo-41025.elf_nz.rst b/Misc/NEWS.d/next/Library/2020-06-18-10-34-59.bpo-41025.elf_nz.rst
new file mode 100644
index 00000000000..21e184d0a40
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-18-10-34-59.bpo-41025.elf_nz.rst
@@ -0,0 +1,2 @@
+Fixed an issue preventing the C implementation of :class:`zoneinfo.ZoneInfo`
+from being subclassed.
diff --git a/Modules/_zoneinfo.c b/Modules/_zoneinfo.c
index bee84cbf8f9..12b3969959b 100644
--- a/Modules/_zoneinfo.c
+++ b/Modules/_zoneinfo.c
@@ -2557,7 +2557,7 @@ static PyMethodDef zoneinfo_methods[] = {
     {"_unpickle", (PyCFunction)zoneinfo__unpickle, METH_VARARGS | METH_CLASS,
      PyDoc_STR("Private method used in unpickling.")},
     {"__init_subclass__", (PyCFunction)(void (*)(void))zoneinfo_init_subclass,
-     METH_VARARGS | METH_KEYWORDS,
+     METH_VARARGS | METH_KEYWORDS | METH_CLASS,
      PyDoc_STR("Function to initialize subclasses.")},
     {NULL} /* Sentinel */
 };