[Python-Dev] Weird problem with exceptions raised in extension module

[Greg Ewing]

I'm getting strange behaviour when raising an
exception in a extension module generated by
Pyrex. The extension module does the equivalent of

  def foo():
    raise TypeError("Test-Exception")

If I invoke it with the following Python code:

  try:
    mymodule.foo()
  except IOError:
    print "blarg"

the following happens:

  Traceback (most recent call last):
    File "<stdin>", line 3, in ?
  SystemError: 'finally' pops bad exception

This only happens when the try-except catches
something *other* than the exception being raised.
If the exception being raised is caught, or
no exception catching is done, the exception
is handled properly.

Also, it only happens when an *intance* is used
as the exception object. If I do this instead:

  raise TypeError, "Test-Exception"

the problem doesn't occur.

The relevant piece of C code generated by
Pyrex is as follows. Can anyone see if I'm
doing anything wrong? (I'm aware that there's
a missing Py_DECREF, but it shouldn't be
causing this sort of thing.)

The Python version I'm using is 2.2.

  __pyx_1 = __Pyx_GetName(__pyx_b, "TypeError"); 
  if (!__pyx_1) goto __pyx_L1;
  __pyx_2 = PyString_FromString(__pyx_k1); 
  if (!__pyx_2) goto __pyx_L1;
  __pyx_3 = PyTuple_New(1); 
  if (!__pyx_3) goto __pyx_L1;
  PyTuple_SET_ITEM(__pyx_3, 0, __pyx_2);
  __pyx_2 = 0;
  __pyx_4 = PyObject_CallObject(__pyx_1, __pyx_3); 
  if (!__pyx_4) goto __pyx_L1;
  Py_DECREF(__pyx_3); 
  __pyx_3 = 0;
  PyErr_SetNone(__pyx_4);
  Py_DECREF(__pyx_4); 
  __pyx_4 = 0;
  goto __pyx_L1;

  /*...*/

  __pyx_L1:;
  Py_XDECREF(__pyx_1);
  Py_XDECREF(__pyx_2);
  Py_XDECREF(__pyx_3);
  Py_XDECREF(__pyx_4);
  __pyx_r = 0;
  __pyx_L0:;
  return __pyx_r;

Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | A citizen of NewZealandCorp, a	  |
Christchurch, New Zealand	   | wholly-owned subsidiary of USA Inc.  |
greg@cosc.canterbury.ac.nz	   +--------------------------------------+