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Date: Thu, 4 Aug 2016 13:19:27 +0200 (CEST)
From: Julia Lawall <julia.lawall@lip6.fr>
To: NeilBrown <neilb@suse.com>
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Cc: ksummit-discuss@lists.linuxfoundation.org
Subject: Re: [Ksummit-discuss] [CORE TOPIC] More useful types in the linux
 kernel
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On Thu, 4 Aug 2016, NeilBrown wrote:

> On Fri, Jul 22 2016, Julia Lawall wrote:
> >
> > In C, enums are ints.  Is there a Gcc option that checks them?  For
> > example, the following program compiles fine with -Wall:
> >
> > enum one {ONE=1, TWO=2, THREE=3};
> > enum two {ONEX=7, TWOX=8, THREEX=9};
> >
> > int f (int x) {
> >   enum one o = ONE;
> >   enum two t = THREEX;
> >   if (x) o = t; else t = o;
> >   return 0;
> > }
>
> However with this slight change (and line-numbers added for clarity)
>
>      1
>      2	enum one {ONE=1, TWO=2, THREE=3} __attribute((bitwise));
>      3	enum two {ONEX=7, TWOX=8, THREEX=9} __attribute((bitwise));
>      4
>      5	int f (int x) {
>      6	  enum one o = ONE;
>      7	  enum two t = THREEX;
>      8	  if (x) o = t; else t = o;
>      9	  return 0;
>     10	}
>
>
> sparse complains:
>
> /tmp/test.c:8:14: warning: mixing different enum types
> /tmp/test.c:8:14:     int enum two  versus
> /tmp/test.c:8:14:     int enum one
> /tmp/test.c:8:26: warning: mixing different enum types
> /tmp/test.c:8:26:     int enum one  versus
> /tmp/test.c:8:26:     int enum two
>
> Is that what you were hoping for?

Yes, perfect, thanks.

julia