From 8e4783273709df286fb6a83506ead4df8483a695 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Thu, 18 Jul 2013 01:49:30 +0200
Subject: [PATCH] Issue #18408: PyObject_Str(), PyObject_Repr() and type_call()
 now fail with an assertion error if they are called with an exception set
 (PyErr_Occurred()).

As PyEval_EvalFrameEx(), they may clear the current exception and so the caller
looses its exception.
---
 Objects/object.c     | 16 ++++++++++++++++
 Objects/typeobject.c |  7 +++++++
 2 files changed, 23 insertions(+)

diff --git a/Objects/object.c b/Objects/object.c
index e957d9d7b0..47d3ebd2ca 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -377,6 +377,14 @@ PyObject_Repr(PyObject *v)
     if (Py_TYPE(v)->tp_repr == NULL)
         return PyUnicode_FromFormat("<%s object at %p>",
                                     v->ob_type->tp_name, v);
+
+#ifdef Py_DEBUG
+    /* PyObject_Repr() must not be called with an exception set,
+       because it may clear it (directly or indirectly) and so the
+       caller looses its exception */
+    assert(!PyErr_Occurred());
+#endif
+
     res = (*v->ob_type->tp_repr)(v);
     if (res == NULL)
         return NULL;
@@ -408,6 +416,7 @@ PyObject_Str(PyObject *v)
 #endif
     if (v == NULL)
         return PyUnicode_FromString("<NULL>");
+
     if (PyUnicode_CheckExact(v)) {
 #ifndef Py_DEBUG
         if (PyUnicode_READY(v) < 0)
@@ -419,6 +428,13 @@ PyObject_Str(PyObject *v)
     if (Py_TYPE(v)->tp_str == NULL)
         return PyObject_Repr(v);
 
+#ifdef Py_DEBUG
+    /* PyObject_Str() must not be called with an exception set,
+       because it may clear it (directly or indirectly) and so the
+       caller looses its exception */
+    assert(!PyErr_Occurred());
+#endif
+
     /* It is possible for a type to have a tp_str representation that loops
        infinitely. */
     if (Py_EnterRecursiveCall(" while getting the str of an object"))
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c970ada1df..0eea38443f 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -736,6 +736,13 @@ type_call(PyTypeObject *type, PyObject *args, PyObject *kwds)
         return NULL;
     }
 
+#ifdef Py_DEBUG
+    /* type_call() must not be called with an exception set,
+       because it may clear it (directly or indirectly) and so the
+       caller looses its exception */
+    assert(!PyErr_Occurred());
+#endif
+
     obj = type->tp_new(type, args, kwds);
     if (obj != NULL) {
         /* Ugly exception: when the call was type(something),
-- 
2.40.0