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Re: [wwwdocs] Porting to again
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Marek Polacek <polacek at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 18 Feb 2015 13:16:55 +0100
- Subject: Re: [wwwdocs] Porting to again
- Authentication-results: sourceware.org; auth=none
- References: <20150218120430 dot GX23138 at redhat dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
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.
Otherwise, LGTM.
Jakub