Re: [Qemu-devel] [PATCH 2/8] osdep.h: Define macros for the benefit of C++ before C++11

[Eric Blake <eblake@redhat.com>]

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On 02/18/2016 11:05 AM, Peter Maydell wrote:
> For C++ before C++11, <stdint.h> requires definition of the macros
> __STDC_CONSTANT_MACROS, __STDC_LIMIT_MACROS and __STDC_FORMAT_MACROS
> in order to enable definition of various macros by the header file.
> Define these in osdep.h, so that we get the right header file
> definitions whether osdep.h is being used by plain C, C++11 or
> older C++.
> 
> In particular libvixl's header files depend on this and won't
> compile if osdep.h is included before them otherwise.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/qemu/osdep.h | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

> +/* Older versions of C++ don't get definitions of various macros from
> + * stdlib.h unless we define these macros before first inclusion of
> + * that system header.
> + */
> +#ifndef __STDC_CONSTANT_MACROS
> +#define __STDC_CONSTANT_MACROS
> +#endif

Style nit: In libvirt, we've grown used to writing:

#ifndef ...
# define ...
#endif

that is, use spacing to make it more visually obvious what level of
conditional nesting is in effect during preprocessor lines.  But short
of a tree-wide change to enforce that style (which I'm not advocating),
it's more of a food for thought comment, and has no bearing on taking
this series as is.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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