[wwwdocs] Porting to again

[Marek Polacek]

On Wed, Feb 18, 2015 at 01:16:55PM +0100, Jakub Jelinek wrote:
> On Wed, Feb 18, 2015 at 01:04:30PM +0100, Marek Polacek wrote:
> > --- porting_to.html	10 Feb 2015 11:12:20 -0000	1.3
> > +++ porting_to.html	18 Feb 2015 12:01:50 -0000
> > @@ -24,6 +24,17 @@
> >  manner. Additions and suggestions for improvement are welcome.
> >  </p>
> >  
> > +<h2>Preprocessor issues</h2>
> > +
> > +<p>The preprocessor started to emit line markers to properly distinguish
> > +whether a macro token comes from a system header, or from a normal header
> > +(see <a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60723">PR60723</a>).
> > +These new markers can cause intriguing problems, if the packages aren't ready
> > +to handle them.  To stop the preprocessor from generating the <code>#line</code>
> > +directives, use the <code>-P</code> option, documented
> > +<a href="https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#Preprocessor-Options">here</a>.
> > +</p>
> 
> I think it would be nice to give here some example, like:
> #include <stdlib.h>
> exitfailure EXIT_FAILURE
> and showing that older gcc -E used to emit
> # 2 "test.c" 2
> exitfailure 1
> whereas GCC 5 emits:
> # 2 "test.c" 2
> 
> # 2 "test.c"
> exitfailure 
> # 2 "test.c" 3 4
>            1
> and thus it can break simple tools that expect the tokens on a single line.

Added.

> Otherwise, LGTM.

Thanks, committed now.

	Marek