GH-101578: Normalize the current exception (GH-101607)

* Make sure that the current exception is always normalized.

* Remove redundant type and traceback fields for the current exception.

* Add new API functions: PyErr_GetRaisedException, PyErr_SetRaisedException

* Add new API functions: PyException_GetArgs, PyException_SetArgs

1 files changed, 5 insertions, 7 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index ecb5bf9..a91f5ba 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2902,13 +2902,13 @@ format_kwargs_error(PyThreadState *tstate, PyObject *func, PyObject *kwargs)
         }
     }
     else if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
-        PyObject *exc, *val, *tb;
-        _PyErr_Fetch(tstate, &exc, &val, &tb);
-        if (val && PyTuple_Check(val) && PyTuple_GET_SIZE(val) == 1) {
+        PyObject *exc = _PyErr_GetRaisedException(tstate);
+        PyObject *args = ((PyBaseExceptionObject *)exc)->args;
+        if (exc && PyTuple_Check(args) && PyTuple_GET_SIZE(args) == 1) {
             _PyErr_Clear(tstate);
             PyObject *funcstr = _PyObject_FunctionStr(func);
             if (funcstr != NULL) {
-                PyObject *key = PyTuple_GET_ITEM(val, 0);
+                PyObject *key = PyTuple_GET_ITEM(args, 0);
                 _PyErr_Format(
                     tstate, PyExc_TypeError,
                     "%U got multiple values for keyword argument '%S'",
@@ -2916,11 +2916,9 @@ format_kwargs_error(PyThreadState *tstate, PyObject *func, PyObject *kwargs)
                 Py_DECREF(funcstr);
             }
             Py_XDECREF(exc);
-            Py_XDECREF(val);
-            Py_XDECREF(tb);
         }
         else {
-            _PyErr_Restore(tstate, exc, val, tb);
+            _PyErr_SetRaisedException(tstate, exc);
         }
     }
 }