Re: checkpatch, a patch checking script.

Andrew Morton
2007-05-02T20:30:20Z

On Wed, 2 May 2007 21:55:16 +0200 (CEST)
Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> wrote:

> On Wed, 2 May 2007, Andrew Morton wrote:
> > On Wed, 2 May 2007 17:32:49 +0200 (CEST)
> > Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> wrote:
> >
> > > On Wed, 2 May 2007, Christoph Hellwig wrote:
> > > > On Wed, May 02, 2007 at 04:28:27PM +0200, Geert Uytterhoeven wrote:
> > > > > - Check for GNU extension __FUNCTION__
> > > >
> > > > __FUNCTION__ is prefered over __func__
> > >
> > > Is there a reason for that?
> > > - __FUNCTION__ is a GNU extension
> > > - __func__ is C99
> > > - __func__ is shorter to type ;-)
> > >
> >
> > In that case we should use __func__.
> >
> > But we discussed this at some length 3-4 years ago and decided to use
> > __FUNCTION__. I don't remember why. Perhaps problems with gcc support for
> > __func__?
>
> I tried gcc 2.95/3.2/3.3/3.4/4.0/4.1, they all recognize __func__ and
> __FUNCTION__, like in e.g. printf("%s", __func__);
>
> > (It could have been that compile-time string concatenation was involved:
> >
> >
> > printf("xxx" __FILE__); /* works */
> > printf("xxx" __FUNCTION__); /* doesn't */
> >
> > Or not.)
>
> Yep, when trying concatenation, I got:
> - 2.95: works fine
> - 3.2:
> syntax error before "__func__"
> warning: concatenation of string literals with __FUNCTION__ is deprecated
> - 3.3:
> error: syntax error before "__func__"
> warning: concatenation of string literals with __FUNCTION__ is deprecated
> - 3.4/4.0:
> error: syntax error before "__func__"
> error: syntax error before "__FUNCTION__"
> - 4.1:
> error: expected ')' before '__func__'
> error: expected ')' before '__FUNCTION__'
>
> Hence gcc 3.2 and up treat __func__ like the a variable, as per C99, while
> __FUNCTION__ has been moving from a virtual preprocessor definition in 2.95 to
> a variable, like __func__.
>
> So in the end it doesn't matter, as concatenation has been fixed in the Linux
> source tree anyway.
>

Great, thanks for working all that out.

So __func__ it is. In new code. However "convert __FUNCTION__ to
__func__" patches will be cheerfully ignored - life is too short.

err, kernel.h has

/* Trap pasters of __FUNCTION__ at compile-time */
#define __FUNCTION__ (__func__)