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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Matt Kraai <kraai@ftbfs.org>, git@vger.kernel.org
Subject: Re: [PATCH 3/3] wt-status: use "format" function attribute for status_printf
Date: Tue, 09 Jul 2013 22:26:04 -0700	[thread overview]
Message-ID: <7vmwpvt28j.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <20130710002328.GC19423@sigill.intra.peff.net> (Jeff King's message of "Tue, 9 Jul 2013 20:23:28 -0400")

Jeff King <peff@peff.net> writes:

> These functions could benefit from the added compile-time
> safety of having the compiler check printf arguments.
>
> Unfortunately, we also sometimes pass an empty format string,
> which will cause false positives with -Wformat-zero-length.
> In this case, that warning is wrong because our function is
> not a no-op with an empty format: it may be printing
> colorized output along with a trailing newline.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> I'm torn on this one. It really does provide us with more compile-time
> safety checks, but it's annoying that "-Wall -Werror" will no longer
> work out of the box.

Yeah, that is a show-stopper for me X-<.

> We could also add a status_printf_empty_line() function, but that feels
> like a bit of a hack. Searching online, I also found the amusing
> suggestion to do:
>
>   status_printf_ln(s, color, "%.*s", 0,
>                    "-Wformat-zero-length please choke on a bucket of socks");
>
> but I think that is probably worse than adding a specialized function.
>
>  wt-status.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/wt-status.h b/wt-status.h
> index 4121bc2..fb7152e 100644
> --- a/wt-status.h
> +++ b/wt-status.h
> @@ -96,9 +96,9 @@ void wt_porcelain_print(struct wt_status *s);
>  void wt_shortstatus_print(struct wt_status *s);
>  void wt_porcelain_print(struct wt_status *s);
>  
> -void status_printf_ln(struct wt_status *s, const char *color, const char *fmt, ...)
> -	;
> -void status_printf(struct wt_status *s, const char *color, const char *fmt, ...)
> -	;
> +__attribute__((format (printf, 3, 4)))
> +void status_printf_ln(struct wt_status *s, const char *color, const char *fmt, ...);
> +__attribute__((format (printf, 3, 4)))
> +void status_printf(struct wt_status *s, const char *color, const char *fmt, ...);
>  
>  #endif /* STATUS_H */

  reply	other threads:[~2013-07-10  5:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-09  5:18 [PATCH] remote-http: use argv-array Junio C Hamano
2013-07-09  6:05 ` Bert Wesarg
2013-07-09  6:38   ` Jeff King
2013-07-09 22:27     ` Matt Kraai
2013-07-10  0:16       ` Jeff King
2013-07-10  0:18         ` [PATCH 1/3] add missing "format" function attributes Jeff King
2013-07-10  0:19         ` [PATCH 2/3] use "sentinel" function attribute for variadic lists Jeff King
2013-07-10  0:23         ` [PATCH 3/3] wt-status: use "format" function attribute for status_printf Jeff King
2013-07-10  5:26           ` Junio C Hamano [this message]
2013-07-10  5:28             ` Jeff King
2013-07-10  5:35               ` Junio C Hamano
2013-07-10  5:40                 ` Jeff King
2013-07-10  5:52                   ` Junio C Hamano
2013-07-10  6:11                     ` Jeff King
2013-07-10  6:17                       ` Junio C Hamano
2013-07-12 16:10               ` Junio C Hamano
2013-07-12 20:44                 ` Jeff King

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