From be64bc8b4f87491298750506297166c1da642ad0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 26 Aug 2024 18:33:30 +0200
Subject: [PATCH 1/3] fix out-of-bounds linenos in `findsource`

---
 Lib/inspect.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 90c44cf74007a8..12d9646671e348 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -973,7 +973,10 @@ def findsource(object):
             firstlineno = vars(object)['__firstlineno__']
         except (TypeError, KeyError):
             raise OSError('source code not available')
-        return lines, firstlineno - 1
+        lnum = firstlineno - 1
+        if lnum >= len(lines) or lnum < 0:
+            raise OSError('lineno is out of bounds')
+        return lines, lnum
 
     if ismethod(object):
         object = object.__func__

From 4906c2ddddf0f7faa68c2b80135c6d095ec14b0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 26 Aug 2024 18:35:35 +0200
Subject: [PATCH 2/3] blurb

---
 .../next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst

diff --git a/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst b/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst
new file mode 100644
index 00000000000000..225c368510b3c6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst
@@ -0,0 +1,2 @@
+Fix handling of ``__firstlineno__`` in :func:`inspect.findsource` for
+classes. Patch by Bénédikt Tran.

From ba2580314f9caed51dbec3869ef3d4f1d402eabd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 26 Aug 2024 18:43:54 +0200
Subject: [PATCH 3/3] inspect.findsource does not exist?

---
 .../next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst b/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst
index 225c368510b3c6..965c51b2282c91 100644
--- a/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst
+++ b/Misc/NEWS.d/next/Library/2024-08-26-18-35-32.gh-issue-123339.o6rDJ9.rst
@@ -1,2 +1,2 @@
-Fix handling of ``__firstlineno__`` in :func:`inspect.findsource` for
+Fix handling of ``__firstlineno__`` in :func:`!inspect.findsource` for
 classes. Patch by Bénédikt Tran.