[Python-bugs-list] [ python-Bugs-575229 ] multiple inheritance w/ slots dumps core

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Bugs item #575229, was opened at 2002-06-29 01:33
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=575229&group_id=5470

Category: Python Interpreter Core
Group: Python 2.2.1
Status: Open
Resolution: None
Priority: 5
Submitted By: Cesar Douady (douady)
Assigned to: Nobody/Anonymous (nobody)
Summary: multiple inheritance w/ slots dumps core

Initial Comment:
The following script dumps a core (revision 2.2.1) :

class A(object): __slots__=()
class B(object): pass
class C(A,B) : __slots__=()
C().x=2

basic sizes for those classes are:
A => 8 (correct : no dict, no weakref)
B => 16 (correct : dict and weakref slots added)
C => 8 (incorrect : dict and weakref not inherited from
B)

in the last lines of type_new, variables add_dict and
add_weak
are exploited to add those slots, but only when
slots==NULL.
The best base selected for C is A, which is correct in
my opinion
since slots come from it, but dict and weak refs must
be treated
specially and can come from another base.

I have seen nothing in the cvs repository which may fix
this bug.

I did not submit a patch since this is a touchy part of
the interpreter,
but I may do it upon request.

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