archive mirror
 help / color / mirror / Atom feed
From: Andy Shevchenko <>
To: Joe Perches <>
Cc: Jonathan Corbet <>,
	Linux Documentation List <>,
	linux-kernel <>,
	Louis Taylor <>
Subject: Re: [PATCH] docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi]
Date: Sat, 7 Sep 2019 23:23:53 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sat, Sep 7, 2019 at 9:15 PM Joe Perches <> wrote:
> Standard integer promotion is already done and %hx and %hhx is useless
> so do not encourage the use of %hh[xudi] or %h[xudi].
> As Linus said in:
> Link:
> It's a pointless warning, making for more complex code, and
> making people remember esoteric printf format details that have no
> reason for existing.
> The "h" and "hh" things should never be used. The only reason for them
> being used if if you have an "int", but you want to print it out as a
> "char" (and honestly, that is a really bad reason, you'd be better off
> just using a proper cast to make the code more obvious).
> So if what you have a "char" (or unsigned char) you should always just
> print it out as an "int", knowing that the compiler already did the
> proper type conversion.

> -               char                    %hhd or %hhx
> -               short int               %hd or %hx
> +               char                    %d or %x
> +               short int               %d or %x

> +               s8                      %d or %x
> +               s16                     %d or %x

This is incorrect. Integral promotions promotes also sign, which will
produce too many f:s.

With Best Regards,
Andy Shevchenko

  parent reply	other threads:[~2019-09-07 20:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 21:11 Joe Perches
2019-09-06 21:37 ` Louis Taylor
2019-09-07 20:23 ` Andy Shevchenko [this message]
2019-09-09  9:36 ` Jani Nikula
2019-09-14  7:58 ` Jonathan Corbet

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='' \ \ \ \ \ \ \
    --subject='Re: [PATCH] docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi]' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).