Re: NULL = ((void *)0) problem

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Article #789

#789

From: Jason Merrill
Date: Tue, 10 Oct 1995 02:27

19 lines
1503 bytes

>>>>> rjf  <rjf@infograph.com> writes:

> This thread (which I started) has been very interesting, and I
> actually understand some of it -- however, I am curious -- is the
> assertion by the GNU compiler that ANSI does not allow the conversion
> of ((void *)0) to some object pointer valid?

ANSI does not allow implicit conversion from (void *) to any non-void
pointer type; it does not make a special case of (void*)0.  g++ does make a
special case of (void*)0, and allows it to be used as a null pointer
constant in most cases.  Apparently there is a bug such that

A* ap = blarg ();
A* ap2 = foo () ? NULL : ap;

where NULL is defined to be (void *)0 causes an error.  This is a bug in
the extension.

Jason

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Path: arc1-ca.pugleaf.net!cygnus.com!usenet
From: jason@cygnus.com (Jason Merrill)
Newsgroups: gnu.g++.help,comp.lang.c++
Subject: Re: NULL = ((void *)0) problem
Date: 09 Oct 1995 19:27:41 -0700
Organization: Cygnus Support, Mountain View, CA
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