From 6c1a4fb6d400827155fd70e48d682e35397731a1 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Wed, 20 Nov 2024 12:27:19 -0500
Subject: [PATCH] gh-121058: Warn if `PyThreadState_Clear` is called with an
 exception set (gh-121343)

---
 .../C API/2024-07-03-13-39-13.gh-issue-121058.MKi1MV.rst     | 2 ++
 Python/pystate.c                                             | 5 +++++
 2 files changed, 7 insertions(+)
 create mode 100644 Misc/NEWS.d/next/C API/2024-07-03-13-39-13.gh-issue-121058.MKi1MV.rst

diff --git a/Misc/NEWS.d/next/C API/2024-07-03-13-39-13.gh-issue-121058.MKi1MV.rst b/Misc/NEWS.d/next/C API/2024-07-03-13-39-13.gh-issue-121058.MKi1MV.rst
new file mode 100644
index 00000000000..133d8cb6fe4
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2024-07-03-13-39-13.gh-issue-121058.MKi1MV.rst	
@@ -0,0 +1,2 @@
+``PyThreadState_Clear()`` now warns (and calls ``sys.excepthook``) if the
+thread state still has an active exception.
diff --git a/Python/pystate.c b/Python/pystate.c
index 01e54fc745d..44f55be5b5b 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -1649,6 +1649,11 @@ PyThreadState_Clear(PyThreadState *tstate)
           "PyThreadState_Clear: warning: thread still has a frame\n");
     }
 
+    if (verbose && tstate->current_exception != NULL) {
+        fprintf(stderr, "PyThreadState_Clear: warning: thread has an exception set\n");
+        _PyErr_Print(tstate);
+    }
+
     /* At this point tstate shouldn't be used any more,
        neither to run Python code nor for other uses.