Re: [Xen-devel] [PATCH] libxl: Introduce LIBXL_DOMAIN_TYPE_INVALID to make gcc happy

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-05-18 at 16:11 +0100, Christoph Egger wrote:
> On 05/18/12 16:55, Ian Campbell wrote:
> 
> > On Fri, 2012-05-18 at 15:48 +0100, Dario Faggioli wrote:
> >> On Fri, 2012-05-18 at 15:39 +0100, Ian Campbell wrote:
> >>>> Which actually seems to be right:
> >>>>
> >>>> $ grep LIBXL_DOMAIN_TYPE_INVALID tools/* -R
> >>>> tools/libxl/libxl_dm.c:    case LIBXL_DOMAIN_TYPE_INVALID:
> >>>> tools/libxl/libxl_dm.c:    case LIBXL_DOMAIN_TYPE_INVALID:
> >>>> tools/libxl/libxl_dom.c:        return LIBXL_DOMAIN_TYPE_INVALID;
> >>>> tools/libxl/libxl_dom.c:        return LIBXL_DOMAIN_TYPE_INVALID;
> >>>> tools/libxl/libxl.c:        case LIBXL_DOMAIN_TYPE_INVALID:
> >>>>
> >>>> Am I missing something?
> >>>
> >>> This should be defined in tools/libxl/libxl_types.idl but the patch
> >>> doesn't seem to add it.
> >>>
> >> Yep, I'm adding it myself with the attached patch, but I'm now getting
> >> this:
> >>
> >> _libxl_types.c: In function âlibxl_domain_build_info_disposeâ:
> >> _libxl_types.c:91:5: error: enumeration value âLIBXL_DOMAIN_TYPE_INVALIDâ 
> >> not handled in switch [-Werror=switch]
> >> _libxl_types.c: In function âlibxl_domain_build_info_init_typeâ:
> >> _libxl_types.c:284:5: error: enumeration value âLIBXL_DOMAIN_TYPE_INVALIDâ 
> >> not handled in switch [-Werror=switch]
> >> testidl.c: In function âlibxl_domain_build_info_rand_initâ:
> >> testidl.c:366:5: error: enumeration value âLIBXL_DOMAIN_TYPE_INVALIDâ not 
> >> handled in switch [-Werror=switch]
> >> _libxl_types.c: In function âlibxl_domain_build_info_gen_jsonâ:
> >> _libxl_types.c:1713:5: error: enumeration value 
> >> âLIBXL_DOMAIN_TYPE_INVALIDâ not handled in switch [-Werror=switch]
> >> cc1: all warnings being treated as errors
> >>
> >> :-O
> > 
> > I wonder if just changing the return type of libxl__domain_type to int
> > would be better than this? I guess it'll probably be much the same.
> 
> 
> Is libxl_domain_type part of the API ?
>  If yes then it is better to use
> 'int' and change the enum to #defines to be safe side. An enum used
> in the API has a backward-compatibility issue related to its size:
> 
> An enum is as small as possible to hold the largest value.
> Whatever 'as small as possible' means depends on the architecture.

It is an API, but libxl only guarantees a stable API, it doesn't
guarantee a stable ABI, so I think these problems do not manifest.

Ian.


> Christoph
> 



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