bpo-29587: Make gen.throw() chain exceptions with yield from (GH-19858)
The previous commits on bpo-29587 got exception chaining working
with gen.throw() in the `yield` case. This patch also gets the
`yield from` case working.
As a consequence, implicit exception chaining now also works in
the asyncio scenario of awaiting on a task when an exception is
already active.
Tests are included for both the asyncio case and the pure
generator-only case.
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 5b253ed..fb01e58 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -217,6 +217,18 @@
assert(f->f_back == NULL);
f->f_back = tstate->frame;
+ _PyErr_StackItem *gi_exc_state = &gen->gi_exc_state;
+ if (exc && gi_exc_state->exc_type != NULL &&
+ gi_exc_state->exc_type != Py_None)
+ {
+ Py_INCREF(gi_exc_state->exc_type);
+ Py_XINCREF(gi_exc_state->exc_value);
+ Py_XINCREF(gi_exc_state->exc_traceback);
+ _PyErr_ChainExceptions(gi_exc_state->exc_type,
+ gi_exc_state->exc_value,
+ gi_exc_state->exc_traceback);
+ }
+
gen->gi_running = 1;
gen->gi_exc_state.previous_item = tstate->exc_info;
tstate->exc_info = &gen->gi_exc_state;
@@ -512,16 +524,6 @@
}
PyErr_Restore(typ, val, tb);
-
- _PyErr_StackItem *gi_exc_state = &gen->gi_exc_state;
- if (gi_exc_state->exc_type != NULL && gi_exc_state->exc_type != Py_None) {
- Py_INCREF(gi_exc_state->exc_type);
- Py_XINCREF(gi_exc_state->exc_value);
- Py_XINCREF(gi_exc_state->exc_traceback);
- _PyErr_ChainExceptions(gi_exc_state->exc_type,
- gi_exc_state->exc_value,
- gi_exc_state->exc_traceback);
- }
return gen_send_ex(gen, Py_None, 1, 0);
failed_throw: