From 26f18b8540b49d592af66361f8df1a03953d1768 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Tue, 23 Feb 2021 14:58:47 +0000
Subject: [PATCH] bpo-43146: fix regression in traceback.print_exception(None)
 (GH-24463)

---
 Lib/test/test_traceback.py                     | 18 ++++++++++++++++++
 Lib/traceback.py                               |  4 +++-
 .../2021-02-06-21-21-35.bpo-43146.MHtb2v.rst   |  1 +
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2021-02-06-21-21-35.bpo-43146.MHtb2v.rst

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 33bdda02666..2261ea99420 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -232,6 +232,24 @@ class TracebackCases(unittest.TestCase):
         output = traceback.format_exception_only(Exception("projector"))
         self.assertEqual(output, ["Exception: projector\n"])
 
+    def test_exception_is_None(self):
+        NONE_EXC_STRING = 'NoneType: None\n'
+        excfile = StringIO()
+        traceback.print_exception(None, None, None, file=excfile)
+        self.assertEqual(excfile.getvalue(), NONE_EXC_STRING)
+
+        excfile = StringIO()
+        traceback.print_exc(None, file=excfile)
+        self.assertEqual(excfile.getvalue(), NONE_EXC_STRING)
+
+        self.assertEqual(traceback.format_exc(None), NONE_EXC_STRING)
+        self.assertEqual(
+            traceback.format_exception(None, None, None), [NONE_EXC_STRING])
+        self.assertEqual(
+            traceback.format_exception_only(None), [NONE_EXC_STRING])
+        self.assertEqual(
+            traceback.format_exception_only(None, None), [NONE_EXC_STRING])
+
 
 class TracebackFormatTests(unittest.TestCase):
 
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 090465a3584..dfb296c5e7b 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -528,7 +528,9 @@ class TracebackException:
                     cause = None
 
                 if compact:
-                    need_context = cause is None and not e.__suppress_context__
+                    need_context = (cause is None and
+                                    e is not None and
+                                    not e.__suppress_context__)
                 else:
                     need_context = True
                 if (e and e.__context__ is not None
diff --git a/Misc/NEWS.d/next/Library/2021-02-06-21-21-35.bpo-43146.MHtb2v.rst b/Misc/NEWS.d/next/Library/2021-02-06-21-21-35.bpo-43146.MHtb2v.rst
new file mode 100644
index 00000000000..8d213a4138e
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-02-06-21-21-35.bpo-43146.MHtb2v.rst
@@ -0,0 +1 @@
+Fix recent regression in None argument handling in :mod:`~traceback` module functions.
\ No newline at end of file