Backport for issue1265 (pdb bug with "with" statement).
When an unfinished generator-iterator is garbage collected, PyEval_EvalFrameEx
is called with a GeneratorExit exception set. This leads to funny results
if the sys.settrace function itself makes use of generators.
A visible effect is that the settrace function is reset to None.
Another is that the eventual "finally" block of the generator is not called.
It is necessary to save/restore the exception around the call to the trace
function.
This happens a lot with py3k: isinstance() of an ABCMeta instance runs
def __instancecheck__(cls, instance):
"""Override for isinstance(instance, cls)."""
return any(cls.__subclasscheck__(c)
for c in {instance.__class__, type(instance)})
which lets an opened generator expression each time it returns True.
And the problem can be reproduced in 2.5 with pure python code.
diff --git a/Python/ceval.c b/Python/ceval.c
index 9dddd2f..4f6b731 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -105,7 +105,7 @@
#endif
static int call_trace(Py_tracefunc, PyObject *, PyFrameObject *,
int, PyObject *);
-static void call_trace_protected(Py_tracefunc, PyObject *,
+static int call_trace_protected(Py_tracefunc, PyObject *,
PyFrameObject *, int, PyObject *);
static void call_exc_trace(Py_tracefunc, PyObject *, PyFrameObject *);
static int maybe_call_line_trace(Py_tracefunc, PyObject *,
@@ -710,8 +710,9 @@
an argument which depends on the situation.
The global trace function is also called
whenever an exception is detected. */
- if (call_trace(tstate->c_tracefunc, tstate->c_traceobj,
- f, PyTrace_CALL, Py_None)) {
+ if (call_trace_protected(tstate->c_tracefunc,
+ tstate->c_traceobj,
+ f, PyTrace_CALL, Py_None)) {
/* Trace function raised an error */
goto exit_eval_frame;
}
@@ -719,9 +720,9 @@
if (tstate->c_profilefunc != NULL) {
/* Similar for c_profilefunc, except it needn't
return itself and isn't called for "line" events */
- if (call_trace(tstate->c_profilefunc,
- tstate->c_profileobj,
- f, PyTrace_CALL, Py_None)) {
+ if (call_trace_protected(tstate->c_profilefunc,
+ tstate->c_profileobj,
+ f, PyTrace_CALL, Py_None)) {
/* Profile function raised an error */
goto exit_eval_frame;
}
@@ -3192,7 +3193,7 @@
}
}
-static void
+static int
call_trace_protected(Py_tracefunc func, PyObject *obj, PyFrameObject *frame,
int what, PyObject *arg)
{
@@ -3201,11 +3202,15 @@
PyErr_Fetch(&type, &value, &traceback);
err = call_trace(func, obj, frame, what, arg);
if (err == 0)
+ {
PyErr_Restore(type, value, traceback);
+ return 0;
+ }
else {
Py_XDECREF(type);
Py_XDECREF(value);
Py_XDECREF(traceback);
+ return -1;
}
}