linux-kernel - Re: [GIT PULL] scheduler fixes

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Message-ID: <dbcc8947-3164-1202-a21e-ebd2a609d997@arm.com>
Date:   Sun, 17 Nov 2019 20:43:24 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] scheduler fixes

On 17/11/2019 16:29, Linus Torvalds wrote:
> Gcc can - and does - narrow enums to smaller integer types with the
> '-fshort-enums' flag.
> 
> However, in practice nobody uses that, and it can cause interop
> problems. So I think for us, enums are always at least 'int' (they can
> be bigger).
> 
> That said, mixing enums and values that are bigger than the enumerated
> ones is just a bad idea
> 
> It will, for example, cause us to miss compiler warnings (eg switch
> statements with an enum will warn if you don't handle all cases, but
> the 'all cases' is based on the actual enum range, not on the
> _possible_ invalid values).
> 

Oh, yet another gcc flag... 

Thanks for the detailed write-up.

>                      Linus
>