Drop ref-counting for list index access

[robertwb]

Follow-up for ticket http://trac.cython.org/ticket/425: ref-counting can also be dropped for list index swap assignments, such as

cdef list l = [l[2](1,2,3,4,5]
l[0],) = l[l[0](2],)

However, this requires changes to the way the __Pyx_GetItemInt*() functions work, as they may do their own Py_INCREF() implicitly.

Migrated from http://trac.cython.org/ticket/438

[robertwb]

scoder changed description from

Follow-up for ticket http://trac.cython.org/ticket/425: ref-counting can also be dropped for list index swap assignments, such as

cdef list l = [l[2](1,2,3,4,5]
l[0],) = l[l[0](2],)

to

Follow-up for ticket http://trac.cython.org/ticket/425: ref-counting can also be dropped for list index swap assignments, such as

cdef list l = [l[2](1,2,3,4,5]
l[0],) = l[l[0](2],)

However, this requires changes to the way the __Pyx_GetItemInt*() functions work, as they may do their own Py_INCREF() implicitly.
commented

[robertwb]

scoder changed component from Code Generation to Optimization
commented