Cython + tuple unpacking

04-23-09, 03:06 PM

Hugues Salamin

Hello,

The following code will crash with a segfault when compiled using cython (v0.11)

def func():
for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
print a, b
print c
print d # This line segfault

Compilation is done using distutils.

If the module is imported in python and func is called, I got a segmentation
fault at the line "print d".

I investigated the error with valgrind and gdb but I still have no clue what is
going on.

I'm on Ubuntu 8.04, Kernel 2.6.24-22-generic

Thanks

04-23-09, 08:56 PM

Aahz

In article <mailman.4434.1240496587.11746.python-list>,
Hugues Salamin <hugues.salamin> wrote:
>
>The following code will crash with a segfault when compiled using
>cython (v0.11)
>
>def func():
> for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
> print a, b
> print c
> print d # This line segfault

Does this crash if you unpack the a,b tuple inside the loop?

04-23-09, 09:39 PM

Stefan Behnel

Hugues Salamin wrote:
> The following code will crash with a segfault when compiled using cython (v0.11)
>
> def func():
> for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
> print a, b
> print c
> print d # This line segfault
>
> Compilation is done using distutils.
>
> If the module is imported in python and func is called, I got a segmentation
> fault at the line "print d".

Yes, this works for me in the latest (unstable) developer branch, but fails
in the release branch:

$ cd cython-unstable
$ cat rangeloop.pyx
def func():
for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
print a, b
print c
print d # This line segfault

$ python2.6 -c 'import pyximport; pyximport.install(); \
import rangeloop; rangeloop.func()'
0 0
0
0
1 1
1
1
2 2
2
2

$ cd ../cython-release
$ python2.6 -c 'import pyximport; pyximport.install(); \
import rangeloop; rangeloop.func()'
0 0
0
Segmentation fault

Not sure why. I'm moving this to the Cython mailing list, we should be able
to help you there.

Stefan

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