Re: [Qemu-devel] [PATCH] fix gcc4 compile warnings

[Andre Przywara]

Andrzej,

> These casts are not the right way to get rid of the warnings, as are
> some of the casts in other files in qemu_put_* and qemu_get_*
> arguments. In this case the warnings are true positives and the bugs
> causing the warnings have to be addressed instead of just the
> warnings.

Are you sure of that? Most of the fixes are like this:
>> -    qemu_put_be32s(f, &s->count_shift);
>> +    qemu_put_be32s(f, (uint32_t *)&s->count_shift);
qemu_put_be32s is (QEMUFile *f, const uint32_t *pv), but after all the 
2nd argument is only a _pointer_ to an unsigned variable, the size is 
the same (thanks to the C99 explicit types). Qemu will dump this value 
straight into a file, in this case signedness does not matter as long as 
put and get use the same. The more cleaner solution would be to 
introduce an explicitly signed prototype for qemu_put_* and qemu_get_* 
and use this where applicable, if you want I will prepare a patch for this.
If you want some real fix, I can dig deeper and make more changes 
(especially the uint8_t vs. char problem), but I wanted to start slowly 
and don't change much code in the first effort.

What solution do you prefer for the opaque types? I have used the simple:
>> -    void *args[MAX_ARGS];
>> +    intptr_t args[MAX_ARGS];
A more portable and clean solution would be this:
-    void *args[MAX_ARGS];
+    union
+    {
+        void* ptr;
+        int i;
+    } args[MAX_ARGS];
If you prefer this, I can change the patch accordingly.

> I will try to do this and apply other parts of your patch
> when I find a bit of time.
Thanks for that, if I can help you with some boring work, tell me ;-)

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 277-84917
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