Re: Implement -Wimplicit-fallthrough (version 9)

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

On 27/09/16 11:41, Jakub Jelinek wrote:
> On Tue, Sep 27, 2016 at 11:32:42AM +0100, Kyrill Tkachov wrote:
> > where the code is:
> > 2156               /* Fall through - if the lane index isn't a constant then
> > 2157                  the next case will error.  */
> > 2158
> > 2159             case NEON_ARG_CONSTANT:
> >
> >
> > Is there supposed to be no empty line between the case statement and the comment?
> > Or is the comment only supposed to contain "Fall through"?
> The last comment before case or default keyword (or user label before
> case/default) has to match one of the following regexps:
> //-fallthrough$
> //@fallthrough@$
> //[ \t]*FALL(S | |-)?THR(OUGH|U)\.?[ \t]*$
> //[ \t]*Fall(s | |-)?[Tt]hr(ough|u)\.?[ \t]*$
> //[ \t]*fall(s | |-)?thr(ough|u)\.?[ \t]*$
> /\*-fallthrough\*/
> /\*@fallthrough@\*/
> /\*[ \t]*FALL(S | |-)?THR(OUGH|U)\.?[ \t]*\*/
> /\*[ \t]*Fall(s | |-)?[Tt]hr(ough|u)\.?[ \t]*\*/
> /\*[ \t]*fall(s | |-)?thr(ough|u)\.?[ \t]*\*/
>
> So, you could e.g. write:
> 	/* If the lane index isn't a constant, then the next case will error.  */
> 	/* Fall through.  */
> but not what you have, free form is not accepted.
Thanks. Given the discussion going on about the acceptable comment formats,
is it preferable to use comments in the gcc codebase at all, or should I
use gcc_fallthrough () (with an explanatory comment if needed)?

Kyrill

> 	Jakub