gh-102192: Replace PyErr_Fetch/Restore etc by more efficient alternat…

…ives in `_ctypes` (#102477)

Modules/_ctypes/_ctypes.c

@@ -2200,7 +2200,6 @@ PyCSimpleType_from_param(PyObject *type, PyObject *value)
     struct fielddesc *fd;
     PyObject *as_parameter;
     int res;
-    PyObject *exc, *val, *tb;
 
     /* If the value is already an instance of the requested type,
        we can use it as is */
@@ -2234,33 +2233,27 @@ PyCSimpleType_from_param(PyObject *type, PyObject *value)
     parg->obj = fd->setfunc(&parg->value, value, 0);
     if (parg->obj)
         return (PyObject *)parg;
-    PyErr_Fetch(&exc, &val, &tb);
+    PyObject *exc = PyErr_GetRaisedException();
     Py_DECREF(parg);
 
     if (_PyObject_LookupAttr(value, &_Py_ID(_as_parameter_), &as_parameter) < 0) {
         Py_XDECREF(exc);
-        Py_XDECREF(val);
-        Py_XDECREF(tb);
         return NULL;
     }
     if (as_parameter) {
         if (_Py_EnterRecursiveCall("while processing _as_parameter_")) {
             Py_DECREF(as_parameter);
             Py_XDECREF(exc);
-            Py_XDECREF(val);
-            Py_XDECREF(tb);
             return NULL;
         }
         value = PyCSimpleType_from_param(type, as_parameter);
         _Py_LeaveRecursiveCall();
         Py_DECREF(as_parameter);
         Py_XDECREF(exc);
-        Py_XDECREF(val);
-        Py_XDECREF(tb);
         return value;
     }
     if (exc) {
-        PyErr_Restore(exc, val, tb);
+        PyErr_SetRaisedException(exc);
     }
     else {
         PyErr_SetString(PyExc_TypeError, "wrong type");

Modules/_ctypes/callproc.c

@@ -1013,41 +1013,43 @@ static PyObject *GetResult(PyObject *restype, void *result, PyObject *checker)
 void _ctypes_extend_error(PyObject *exc_class, const char *fmt, ...)
 {
     va_list vargs;
-    PyObject *tp, *v, *tb, *s, *cls_str, *msg_str;
 
     va_start(vargs, fmt);
-    s = PyUnicode_FromFormatV(fmt, vargs);
+    PyObject *s = PyUnicode_FromFormatV(fmt, vargs);
     va_end(vargs);
-    if (!s)
+    if (s == NULL) {
         return;
+    }
 
-    PyErr_Fetch(&tp, &v, &tb);
-    PyErr_NormalizeException(&tp, &v, &tb);
-    if (PyType_Check(tp))
-        cls_str = PyType_GetName((PyTypeObject *)tp);
-    else
-        cls_str = PyObject_Str(tp);
+    assert(PyErr_Occurred());
+    PyObject *exc = PyErr_GetRaisedException();
+    assert(exc != NULL);
+    PyObject *cls_str = PyType_GetName(Py_TYPE(exc));
     if (cls_str) {
         PyUnicode_AppendAndDel(&s, cls_str);
         PyUnicode_AppendAndDel(&s, PyUnicode_FromString(": "));
-        if (s == NULL)
+        if (s == NULL) {
             goto error;
-    } else
+        }
+    }
+    else {
         PyErr_Clear();
-    msg_str = PyObject_Str(v);
-    if (msg_str)
+    }
+
+    PyObject *msg_str = PyObject_Str(exc);
+    if (msg_str) {
         PyUnicode_AppendAndDel(&s, msg_str);
+    }
     else {
         PyErr_Clear();
         PyUnicode_AppendAndDel(&s, PyUnicode_FromString("???"));
     }
-    if (s == NULL)
+    if (s == NULL) {
         goto error;
+    }
     PyErr_SetObject(exc_class, s);
 error:
-    Py_XDECREF(tp);
-    Py_XDECREF(v);
-    Py_XDECREF(tb);
+    Py_XDECREF(exc);
     Py_XDECREF(s);
 }