On Wed, 28 May 2014 09:23:30 +0200
Juergen Borleis <jbe@xxxxxxxxxxxxxx> wrote:
> Hi Antony,
>
> On Tuesday 27 May 2014 16:04:11 Antony Pavlov wrote:
> > [...]
> > If you use #ifdef:
> >
> > #ifdef CONFIG_DEBUG_FS
> > err = tegra_dsi_debugfs_init(dsi, tegra->drm->primary);
> > if (err < 0)
> > dev_err(dsi->dev, "debugfs setup failed: %d\n", err);
> > #endif
> >
> > then you get jut the same result but without checking the code under #ifdef
> > CONFIG_DEBUG_FS.
>
> A syntax check is always done by the pre-processor. So, the code between the
Yes, the C pre-processor checks the syntax for input, but only the C pre-procesor directive syntax!
But here I mean exactly C code checking.
> #ifdef/#endif must be valid C code or be commented out.
> But there is no further check, because the lines between the #ifdef/#endif are
> never seen by the compiler.
>
That's exactly what I mean! E.g.
antony@doce:~$ cat > test.c <<EOF;
int main()
{
#ifdef SOME_UNDEFINED_MACRO
foo bar;
фу бар;
#endif
return 0;
}
EOF
antony@doce:~$ gcc test.c
antony@doce:~$ ./a.out
antony@doce:~$ ./a.out
antony@doce:~$ echo $
0
--
Best regards,
Antony Pavlov
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