Use traceback from exception instead of exc_info in reraise

iritkatriel · web-flow · commit 05af230b8871 · 2021-11-29T00:00:15.000Z
diff --git a/Doc/reference/simple_stmts.rst b/Doc/reference/simple_stmts.rst
@@ -655,6 +655,12 @@ and information about handling exceptions is in section :ref:`try`.
     The ``__suppress_context__`` attribute to suppress automatic display of the
     exception context.
 
+.. versionchanged:: 3.11
+    If the traceback of the active exception is modified in an :keyword:`except`
+    clause, a subsequent ``raise`` statement re-raises the exception with the
+    modified traceback. Previously, the exception was re-raised with the
+    traceback it had when it was caught.
+
 .. _break:
 
 The :keyword:`!break` statement
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
@@ -181,6 +181,12 @@ Other CPython Implementation Changes
   hash-based pyc files now use ``siphash13``, too.
   (Contributed by Inada Naoki in :issue:`29410`.)
 
+* When an active exception is re-raised by a :keyword:`raise` statement with no parameters,
+  the traceback attached to this exception is now always ``sys.exc_info()[1].__traceback__``.
+  This means that changes made to the traceback in the current :keyword:`except` clause are
+  reflected in the re-raised exception.
+  (Contributed by Irit Katriel in :issue:`45711`.)
+
 New Modules
 ===========
 
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -5920,20 +5920,17 @@ do_raise(PyThreadState *tstate, PyObject *exc, PyObject *cause)
     if (exc == NULL) {
         /* Reraise */
         _PyErr_StackItem *exc_info = _PyErr_GetTopmostException(tstate);
-        PyObject *tb;
-        type = exc_info->exc_type;
         value = exc_info->exc_value;
-        tb = exc_info->exc_traceback;
-        assert(((Py_IsNone(value) || value == NULL)) ==
-               ((Py_IsNone(type) || type == NULL)));
         if (Py_IsNone(value) || value == NULL) {
             _PyErr_SetString(tstate, PyExc_RuntimeError,
                              "No active exception to reraise");
             return 0;
         }
+        assert(PyExceptionInstance_Check(value));
+        type = PyExceptionInstance_Class(value);
         Py_XINCREF(type);
         Py_XINCREF(value);
-        Py_XINCREF(tb);
+        PyObject *tb = PyException_GetTraceback(value); /* new ref */
         _PyErr_Restore(tstate, type, value, tb);
         return 1;
     }
