Re: PING [PATCH] mention disabling GCC built-ins for customization

[Martin Sebor <msebor at gmail dot com>]

I have committed the change:
  http://tinyurl.com/y7jbvfs4

Martin

On 06/27/2018 05:37 PM, Martin Sebor wrote:
> Ping: https://sourceware.org/ml/libc-alpha/2018-06/msg00428.html
>
> If there are no further comments I'd like to commit this change
> later this week.
>
> On 06/14/2018 01:11 PM, Martin Sebor wrote:
> > On 06/14/2018 01:25 AM, Andreas Schwab wrote:
> > > On Jun 13 2018, Martin Sebor <msebor@gmail.com> wrote:
> > >
> > > > diff --git a/manual/stdio.texi b/manual/stdio.texi
> > > > index 38be236..d945955 100644
> > > > --- a/manual/stdio.texi
> > > > +++ b/manual/stdio.texi
> > > > @@ -2963,7 +2963,11 @@ The facilities of this section are declared in
> > > > the header file
> > > >
> > > >  @strong{Portability Note:} The ability to extend the syntax of
> > > >  @code{printf} template strings is a GNU extension.  ISO standard C has
> > > > -nothing similar.
> > > > +nothing similar.  When using the GNU C compiler or any other compiler
> > > > +that interprets calls to standard I/O functions according to the rules
> > > > +of the language standard it is necessary to disable such handling by
> > > > +the appropriate compiler option.  Otherwise the behavior of a program
> > > > +that relies on the extension is undefined.
> > >
> > > The manual already says that redefining existing conversions causes
> > > problems:
> > >
> > >     You can redefine the standard output conversions, but this is
> > > probably
> > >     not a good idea because of the potential for confusion.  Library
> > > routines
> > >     written by other people could break if you do this.
> > >
> > > We should extend that with a stronger language, independent of any
> > > compiler behaviour.
> >
> > That sounds fine to me.  Attached is an updated patch that also
> > adds text to this paragraph.  I added a Portability Note before
> > the text to highlight the portability impact, similarly to
> > the prior paragraph.
> >
> > Martin