[Python-Dev] PyPy progress: list of CPython 3.5 crashers and bugs

[Armin Rigo]

Hi all,

PyPy 3.5 is progressing.  It's still alpha status, but we'll give a
progress report on morepypy.blogspot.com at some point.

Now the point of this mail is that when exploring the source code of
CPython 3.5.2+, we found a large number of crashers and bugs.  None of
them are essential---otherwise, they would already have been reported.
However, if the goal of python-dev is still to ensure that CPython
cannot normally be crashed and behaves as documented even in corner
cases, then you are probably interested in them.

I reported the first two crashers, http://bugs.python.org/issue27811
and http://bugs.python.org/issue27812, but then stopped to keep some
focus on PyPy.  I'm instead collecting them here as I find them:
http://bitbucket.org/pypy/extradoc/raw/extradoc/planning/py3.5/cpython-crashers.rst

I didn't systematically check the CPython trunk: the bugs are for
CPython 3.5.2+.  But I did check trunk a few times, and the same bug
was present there too.  So for now I assume that many items on that
list are still up-to-date.

In 3.5.2+ at least, I'm reasonably convinced that all crashers are
real, but I didn't spend the time to come up with actual examples or
patches, beyond the first two items on the list.  There are also
non-crasher bugs where the current behavior is clearly wrong according
to the documentation or the PEP.  I've also added a few points that
strike me as rather strange but not against the documentation.  What
should I do with this list?  From my point of view, I could drop it
all in a single issue, or possibly three of them (crashers, bugs,
"strange").  Alternatively I can go ahead and open one issue per
bullet point.  Which way would you prefer?  Or, if you think there is
no point in me filing issues without actual examples and patches, then
that's fine with me too and I will simply continue to expand my
cpython-crashers.rst file.


Thank you for your attention,

Armin Rigo