Re: [Xen-devel] [Qemu-devel] [PATCH v2 01/16] x86: Convert conditional compilation of debug printfs to regular ifs

[Marc Marà <marc.mari.barcelo@xxxxxxxxx>]

El Tue, 13 May 2014 08:38:26 -0600
Eric Blake <eblake@xxxxxxxxxx> escribiÃ:
> Although __VA_ARGS__ is required by C99, the use of ##__VA_ARGS__ is a
> gcc extension; are you sure that all other supported compilers handle
> it?  (I guess that's just clang)
> 
> If you want something portable to C99, just use one fewer macro
> argument, so that you are guaranteed that __VA_ARGS__ will be
> non-empty (that is, subsume fmt into the ...):
> 
> #define DEBUG(...)                                            \
>     QEMU_DPRINTF(DEVICE_ASSIGNMENT_DEBUG_ENABLED,             \
>                  "pci_assign", __VA_ARGS__)
> 

I found some problems to convert from ## __VA_ARGS__ to __VA_ARGS__ in
some parts, and as I asked in IRC, it was pointed that "our HACKING
document recommends the fmt, ## __VA_ARGS__ approach, and it obviously
works on all the compilers we care about". So I will leave this as it
is now.

Marc

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