From: Han-Wen Nienhuys <hanwen@cs.uu.nl>
Cc: guile-devel@gnu.org
Subject: Re: SCM_PTR_LE ?
Date: Thu, 1 Aug 2002 19:16:53 +0200 [thread overview]
Message-ID: <15689.27909.668671.145902@meddo.cs.uu.nl> (raw)
In-Reply-To: <lj4ree5y7l.fsf@burns.dt.e-technik.uni-dortmund.de>
marius.vollmer@uni-dortmund.de writes:
> > I think that pointer comparison is pretty well defined in ANSI C; can
> > you think of a solid reason to support them?
>
> What is that definition? I think ANSI C only defines the outcome of
> comparisons for pointers that point into the same object, i.e., the
I stand corrected, I looked it up in the N843 document
(http://www.dkuug.dk/JTC1/SC22/WG14/www/docs/n843.htm), and you're
right.
> same array or a single block returned from malloc. A consequence
> would be that you can not reliably test whether a pointer does point
> into some object, since the results are not defined when it points
> outside. For example, is the following guaranteed to print "sane"?
However, that point is completely moot, since the binary search code
in heap_segment () (new GC: scm_find_heap_segment_containing_object)
is full of code that compares pointers outside their blocks. Unless
that is scrapped (not), SCM_PTR_* can go.
--
Han-Wen Nienhuys | hanwen@cs.uu.nl | http://www.cs.uu.nl/~hanwen/
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next prev parent reply other threads:[~2002-08-01 17:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-27 18:50 SCM_PTR_LE ? Han-Wen
2002-07-30 17:00 ` Marius Vollmer
2002-07-30 22:24 ` Han-Wen
2002-08-01 16:40 ` Marius Vollmer
2002-08-01 17:09 ` Mr. Peter Ivanyi
2002-08-01 17:15 ` Lynn Winebarger
2002-08-01 20:08 ` Marius Vollmer
2002-08-01 17:16 ` Han-Wen Nienhuys [this message]
2002-08-01 17:24 ` Han-Wen Nienhuys
2002-08-01 20:09 ` Marius Vollmer
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