The following code crashes python with:

python: Objects/object.c:512: PyObject_Str: Assertion `!PyErr_Occurred()' failed.

on the tip of the default branch, but not on python 3.3.3.


import sys

error = None
try:
    raise ValueError('some text')
except ValueError as err:
    error = err

if error:
    sys.exit(error)

New changeset e7708864a8d5 by Nick Coghlan in branch 'default':
Close #20500: Don't trigger PyObject_Str assertion at shutdown
http://hg.python.org/cpython/rev/e7708864a8d5

Thanks for the report Xavier - 3.4 is a bit fussier about not losing that exception state silently, so the shutdown code simply needed to clear it explicitly after saving it on the local stack.

I also added a versionchanged to PyObject_Str and a note in the Porting section of What's New, as third party extensions could also be affected by this change - it elevates "may silently discard an active exception" to "debug build assertion failure".

"I also added a versionchanged to PyObject_Str and a note in the Porting section of What's New, as third party extensions could also be affected by this change - it elevates "may silently discard an active exception" to "debug build assertion failure"."

Hi, I added this check in many other functions: PyEval_EvalFrameEx(), PyEval_CallObjectWithKeywords(), PyObject_Repr(), PyObject_Str(). And also private methods like type_call().

I added these assertions when I worked on #18408 to ensure that MemoryError exceptions are no more ignored.

New changeset 41023a501c7b by Nick Coghlan in branch 'default':
Issue #20500: Note other public APIs with the new assertion
http://hg.python.org/cpython/rev/41023a501c7b

New changeset 9e7594d65178 by Nick Coghlan in branch 'default':
Issue #20500: clarify that invocation may be indirect
http://hg.python.org/cpython/rev/9e7594d65178

Above commits added notes for the other two currently documented public APIs directly affected by the change (PyEval_CallObjectWithKeywords isn't currently documented, despite the public name), and also updated the porting note to clarify that these operations may be invoked indirectly via other public APIs.