Re: [Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Eric Blake <eblake@redhat.com>]

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On 08/22/2012 01:42 PM, Stefan Weil wrote:
> GLib 2.0 include files use __printf__ for the format attribute
> which resolves to native format strings on w32 hosts.
> 
> QEMU wants standard format strings instead of native format
> strings, so we simply change any declaration with __printf__
> to use __gnu_printf__.
> 
> This works because all basic printf functions support both
> kinds of format strings.
> 
> This fixes a compiler warning:
> 
> qapi/string-output-visitor.c: In function ‘print_type_int’:
> qapi/string-output-visitor.c:34:5: warning: unknown conversion type character ‘l’ in format [-Wformat]
> qapi/string-output-visitor.c:34:5: warning: too many arguments for format [-Wformat-extra-args]
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  compiler.h |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/compiler.h b/compiler.h
> index 07ba1f8..c734a71 100644
> --- a/compiler.h
> +++ b/compiler.h
> @@ -44,6 +44,11 @@
>     /* Use gnu_printf when supported (qemu uses standard format strings). */
>  #  define GCC_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
>  #  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
> +#  if defined(_WIN32)
> +    /* Map __printf__ to __gnu_printf__ because we want standard format strings
> +     * even when MinGW or GLib include files use __printf__. */
> +#   define __printf__ __gnu_printf__
> +#  endif

Don't you need to make this conditional on the gcc version?  That is,
gcc 4.4 added __gnu_printf__, but gcc 4.3 understands only __printf__
and attempts to pass __gnu_printf__ will cause compilation failure.

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


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