From 3b8121f2143b5e8a1f6fc0bef9dff382c2aedbc1 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Fri, 17 Jun 2022 19:32:52 +0100
Subject: [PATCH 1/3] GH-93249: relax overly struct assertion on
 bounds->ar_start

---
 Objects/codeobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index 8ac4e9914f8887..dc27cdb7c96183 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -818,7 +818,7 @@ static void
 retreat(PyCodeAddressRange *bounds)
 {
     ASSERT_VALID_BOUNDS(bounds);
-    assert(bounds->ar_start > 0);
+    assert(bounds->ar_start >= 0);
     do {
         bounds->opaque.lo_next--;
     } while (((*bounds->opaque.lo_next) & 128) == 0);

From 8dde6c655597994c84e7003517f9546aaab0c0c9 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Fri, 17 Jun 2022 23:15:32 +0100
Subject: [PATCH 2/3] add test

---
 Lib/test/test_traceback.py | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 07472e29df45c3..722c265a6a8a51 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -4,6 +4,7 @@
 from io import StringIO
 import linecache
 import sys
+import types
 import inspect
 import unittest
 import re
@@ -1128,7 +1129,7 @@ def test_print_exception_bad_type_python(self):
 class BaseExceptionReportingTests:
 
     def get_exception(self, exception_or_callable):
-        if isinstance(exception_or_callable, Exception):
+        if isinstance(exception_or_callable, BaseException):
             return exception_or_callable
         try:
             exception_or_callable()
@@ -1850,6 +1851,31 @@ def exc():
         report = self.get_report(exc)
         self.assertEqual(report, expected)
 
+    def test_KeyboardInterrupt_at_first_line_of_frame(self):
+        # see GH-93249
+        def f():
+            return sys._getframe()
+
+        tb_next = None
+        frame = f()
+        lasti = 0
+        lineno = f.__code__.co_firstlineno
+        tb = types.TracebackType(tb_next, frame, lasti, lineno)
+
+        exc = KeyboardInterrupt()
+        exc.__traceback__ = tb
+
+        expected = (f'Traceback (most recent call last):\n'
+                    f'  File "{__file__}", line {lineno}, in f\n'
+                    f'    def f():\n'
+                    f'\n'
+                    f'KeyboardInterrupt\n')
+
+        report = self.get_report(exc)
+        # remove trailing writespace:
+        report = '\n'.join([l.rstrip() for l in report.split('\n')])
+        self.assertEqual(report, expected)
+
 
 class PyExcReportingTests(BaseExceptionReportingTests, unittest.TestCase):
     #

From c2138e1345566a126b1952bc32483796e37fe3ed Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Mon, 20 Jun 2022 15:24:48 +0100
Subject: [PATCH 3/3] update previous_code_delta for case of ar_start == 0

---
 Objects/codeobject.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index dc27cdb7c96183..b90a7e1e5d23fe 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -775,6 +775,11 @@ next_code_delta(PyCodeAddressRange *bounds)
 static int
 previous_code_delta(PyCodeAddressRange *bounds)
 {
+    if (bounds->ar_start == 0) {
+        // If we looking at the first entry, the
+        // "previous" entry has an implicit length of 1.
+        return 1;
+    }
     const uint8_t *ptr = bounds->opaque.lo_next-1;
     while (((*ptr) & 128) == 0) {
         ptr--;