Re: [PATCH] tty/n_hdlc: mark expected switch fall-through

[Jiri Slaby]

On 12. 02. 19, 20:19,  Gustavo A. R. Silva  wrote:
> In preparation to enabling -Wimplicit-fallthrough, mark switch
> cases where we are expecting to fall through.
> 
> This patch fixes the following warning:
> 
> drivers/tty/n_hdlc.c: In function ân_hdlc_tty_ioctlâ:
> drivers/tty/n_hdlc.c:775:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    switch (arg) {
>    ^~~~~~
> drivers/tty/n_hdlc.c:782:2: note: here
>   default:
>   ^~~~~~~
> 
> Warning level 3 was used: -Wimplicit-fallthrough=3
> 
> Notice that, in this particular case, the code comment is modified
> in accordance with what GCC is expecting to find.

Oh well, and that is:
> [ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?fall(s | |-)?thr(ough|u)[
\t.!]*(-[^\n\r]*)?

for implicit-fallthrough > 2.

> This patch is part of the ongoing efforts to enable
> -Wimplicit-fallthrough.

But will we ever enable warning > 2? Does it even make sense?

> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
>  drivers/tty/n_hdlc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
> index 8bdf42bc8fc8..e55c79eb6430 100644
> --- a/drivers/tty/n_hdlc.c
> +++ b/drivers/tty/n_hdlc.c
> @@ -777,7 +777,7 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
>  		case TCOFLUSH:
>  			flush_tx_queue(tty);
>  		}
> -		/* fall through to default */
> +		/* fall through - to default */

As the former makes more sense than the latter here.

>  	default:
>  		error = n_tty_ioctl_helper(tty, file, cmd, arg);
> 

thanks,
-- 
js
suse labs