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Date:   Thu, 11 Apr 2019 10:41:09 -0700
From:   Nick Desaulniers <>
To:     Linus Torvalds <>
Cc:     Joe Perches <>, Louis Taylor <>,
        David Howells <>,,
        Linux List Kernel Mailing <>,
Subject: Re: [PATCH] afs: use correct format characters

On Thu, Apr 11, 2019 at 9:31 AM Linus Torvalds
<> wrote:
> On Wed, Apr 10, 2019 at 4:01 PM Joe Perches <> wrote:
> >
> > I really think this clang message should be ignored.
> Agreed.
> > It's really unnecessary as every vararg argument smaller
> > than int size is already promoted to int.
> Exactly. 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.
>                              Linus

I still think -Wformat helpful for catching completely nonsensical
format strings like printing a floating point type as an integral
type, or not having the correct number of arguments for the number of
format strings.  We'll take a look to see if we can differentiate
between those and these "integer widening" ones better.
~Nick Desaulniers

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