bpo-31033: Improve the traceback for cancelled asyncio tasks (GH-19951)

When an asyncio.Task is cancelled, the exception traceback now
starts with where the task was first interrupted.  Previously,
the traceback only had "depth one."

1 files changed, 17 insertions, 0 deletions

diff --git a/Include/internal/pycore_pyerrors.h b/Include/internal/pycore_pyerrors.h
index bae1056..3290a37 100644
--- a/Include/internal/pycore_pyerrors.h
+++ b/Include/internal/pycore_pyerrors.h
@@ -14,6 +14,20 @@ static inline PyObject* _PyErr_Occurred(PyThreadState *tstate)
     return tstate->curexc_type;
 }
 
+static inline void _PyErr_ClearExcState(_PyErr_StackItem *exc_state)
+{
+    PyObject *t, *v, *tb;
+    t = exc_state->exc_type;
+    v = exc_state->exc_value;
+    tb = exc_state->exc_traceback;
+    exc_state->exc_type = NULL;
+    exc_state->exc_value = NULL;
+    exc_state->exc_traceback = NULL;
+    Py_XDECREF(t);
+    Py_XDECREF(v);
+    Py_XDECREF(tb);
+}
+
 
 PyAPI_FUNC(void) _PyErr_Fetch(
     PyThreadState *tstate,
@@ -36,6 +50,9 @@ PyAPI_FUNC(void) _PyErr_SetObject(
     PyObject *type,
     PyObject *value);
 
+PyAPI_FUNC(void) _PyErr_ChainStackItem(
+    _PyErr_StackItem *exc_state);
+
 PyAPI_FUNC(void) _PyErr_Clear(PyThreadState *tstate);
 
 PyAPI_FUNC(void) _PyErr_SetNone(PyThreadState *tstate, PyObject *exception);