[ python-Bugs-980352 ] coercion results used dangerously

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Bugs item #980352, was opened at 2004-06-26 17:26
Message generated for change (Comment added) made by nascheme
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=980352&group_id=5470

Category: Python Interpreter Core
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Armin Rigo (arigo)
Assigned to: Nobody/Anonymous (nobody)
Summary: coercion results used dangerously

Initial Comment:
The C core uses the result of PyNumber_CoerceEx() dangerously: it gets passed to tp_compare, and most tp_compare slots assume they get two objects of the same type.  This assumption is never checked, even when a user-defined __coerce__() is called:

>>> class X(object):
...   def __coerce__(self, other):
...     return 4, other
...
>>> slice(1,2,3) == X()
Segmentation fault


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>Comment By: Neil Schemenauer (nascheme)
Date: 2004-06-26 19:21

Message:
Logged In: YES 
user_id=35752

This bug should obviously get fixed but in long term I think
__coerce__ should go away.  Do you think deprecating it for
2.4 and then removing support for it in 2.5 or 2.6 is feasible?

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=980352&group_id=5470