Re: [Qemu-devel] [PATCH 1/2] Add support for gcc format attribute gnu_printf

[Stefan Weil <weil@mail.berlios.de>]

Am 20.09.2010 21:18, schrieb Blue Swirl:
> On Mon, Sep 13, 2010 at 8:02 PM, Stefan Weil<weil@mail.berlios.de>  wrote:
>    
>> Since version 4.4.x, gcc supports additional format attributes.
>>     __attribute__ ((format (gnu_printf, 1, 2)))
>> should be used instead of
>>     __attribute__ ((format (printf, 1, 2))
>> because QEMU always uses standard format strings (even with mingw32).
>>
>> For older compilers, we simply define gnu_printf = printf,
>> so they work with the new format attribute, too.
>>
>> Signed-off-by: Stefan Weil<weil@mail.berlios.de>
>> ---
>>   configure |   11 +++++++++++
>>   1 files changed, 11 insertions(+), 0 deletions(-)
>>
>> diff --git a/configure b/configure
>> index 4061cb7..1300879 100755
>> --- a/configure
>> +++ b/configure
>> @@ -148,6 +148,17 @@ for flag in $gcc_flags; do
>>      fi
>>   done
>>
>> +# Check gnu_printf (supported by gcc>= 4.4.x).
>> +cat>  $TMPC<<  EOF
>> +static void test(const char *format, ...)
>> +    __attribute__ ((format (gnu_printf, 1, 2)));
>> +static void test(const char *format, ...) {}
>> +int main(void) { test("\n"); return 0; }
>> +EOF
>> +if ! compile_prog "-Werror" ""; then
>> +    QEMU_CFLAGS="-Dgnu_printf=printf $QEMU_CFLAGS"
>>      
> This could cause problems, for example if system headers declared a
> function called gnu_printf.
>
> I'd introduce CONFIG_GCC_FMT_ATTR_GNU_PRINTF and adjust GCC_FMT_ATTR
> definition based on that.
>
>    

Thanks for your review. I'll send a new patch which goes
into the direction which you suggested.

Instead of defining a new macro CONFIG_GCC_FMT_ATTR_GNU_PRINTF,
my new patch checks the gcc version (gnu_printf was introduced
with gcc 4.4). Like this, no changes to file configure are needed.

Regards
Stefan