[Cython] Bug, or changed array assignment in 0.17beta1?

[Stefan Behnel]

Hi,

thanks for the report.

Mike Zaletel, 25.07.2012 00:40:
> The exact behavior of array assignment was never entirely clear to me

Yes, it's not entirely obvious.


> but I am certain the following behavior did not occur in 0.16:
> 
> --------bug.pyx----------
> 
> def foo():
>        cdef int i
>        cdef int* p1 = [4, 4]
>        cdef int* p2 = [5, 5]
> 
>        print "p1:",
>        for i in range(2):
>                print p1[i],
>        print "\np2:",
>        for i in range(2):
>                print p2[i],
> 
> -----------------------------
> 
> which in Cython 0.17beta1 gives me
> 
> >>> import bug
> >>> bug.foo()
> p1: 5 5
> p2: 5 5
> 
> 
> while in Cython 0.16 I get
> 
> >>> import bug
> >>> bug.foo()
> p1: 4 4
> p2: 5 5

The problem is that the same (temporary) local array variable is used in
both cases to build the array, and then only a pointer is assigned, i.e. p1
and p2 then point to the same array, which gets overwritten with the new
values in the second assignment.

Stefan