Re: Compilation Error in extras/mini-os/tpmback.c

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Ian Campbell, le Wed 16 Jul 2014 10:13:31 +0100, a écrit :
> On Wed, 2014-07-16 at 11:25 +0530, Dushyant Behl wrote:
> > I'm trying to compile xen from the source and i'm getting this
> > compilation error while running a make world.
> > 
> > tpmback.c: In function ‘tpmif_change_state’:
> > tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
> > but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
> >     if(sscanf(value, "%d", &readst) != 1) {
> >     ^
> > cc1: all warnings being treated as errors
> > make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
> > Error 1
> > 
> > Could anyone explain that if this is just problem on my side or this
> > is not fixed in the git tree.
> 
> It looks like a legitimate issue to me. I expect you are just the first
> person to use a compiler which picks up in this particular issue.
> 
> I'm not sure what the correct fix is since C doesn't mandate very much
> about the storage size of an enum, so casting is probably not the right
> answer.

Indeed, C99 apparently says “The choice of type is
implementation-defined”, so

> Probably the value needs to be read into an actual int variable and then
> assigned to the enum.

that seems like the proper solution.

Samuel

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