type punning warnings in utils/*

Corinna Vinschen vinschen@redhat.com
Fri Nov 14 16:59:00 GMT 2003


On Fri, Nov 14, 2003 at 10:49:26AM -0500, Christopher Faylor wrote:
> On Fri, Nov 14, 2003 at 11:11:32AM +0100, Corinna Vinschen wrote:
> >On Fri, Nov 14, 2003 at 12:54:32PM +1100, Robert Collins wrote:
> >> On Fri, 2003-11-14 at 12:51, Christopher Faylor wrote:
> >> > On Fri, Nov 14, 2003 at 07:29:05AM +1100, Robert Collins wrote:
> >> > >I just noticed there are a bunch of type punning warnings in the utils
> >> > >collection:
> >> > >
> >> > >Chris, any objection to my just fixing these, under my rarely used
> >> ^^^Corinna^, 
> >> 
> >> > >general committer heading, or would you rather see some patches, as I
> >> > >haven't been active in the guts for quite some time...
> >> > 
> >> > The type-punned warnings are coming from files that are mainly
> >> > maintained by Corinna.
> >> 
> >> Ah, thanks...
> >> 
> >> Corinna ?
> >
> >Huh?  What?  I just rebuilt the utils directory with CFLAGS=-Wall
> >and I don't get any warning.  Could you be a bit more explicit?
> >What do you mean by "type punning", btw?
> 
> i686-pc-cygwin-gcc -c -g -O2 ... mkgroup.c
> /cygnus/src/uberbaum/winsup/utils/mkgroup.c: In function `enum_local_users':
> /cygnus/src/uberbaum/winsup/utils/mkgroup.c:139: warning: dereferencing type-punned pointer will break strict-aliasing rules
> [etc]

Hmm, I'm wondering why my gcc doesn't emit these warnings.  I'm using
gcc from gnupro-03r1 for building.

Anyway, could somebody explain to me what "type-punned" means?  I have
no idea.  And I don't see anything wrong in the affected lines.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.



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