Re: [Qemu-devel] Mingw GCC not recognising printf format "%I64u"

[Jamie Lokier]

Anthony Liguori wrote:
> >>#ifdef _WIN32
> >>#define PRIu64 "%llu"
> >>#endif
> >>
> >Qemu does that already!
> 
> I don't think so.  mingw32 actuallt defines PRIu64 as "%I64u" even 
> though GCC doesn't like it.

Look again.  qemu/qemu-common.h:

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#define WINVER 0x0501  /* needed for ipv6 bits */
#include <windows.h>
...etc...
#define PRId64 "I64d"
#define PRIx64 "I64x"
#define PRIu64 "I64u"
#define PRIo64 "I64o"
#endif

The only condition is whether _WIN32 is defined, which means WIN32
API, except that it's also defined with Cygwin (and other unix
emulations) which have quite different functions.

> FWIW, the following seems to work for me:
> 
> /* Mingw has a broken PRIu64 */
> #if defined(__MINGW32__)
> #undef PRIu64
> #define PRIu64 "Ld"
> #endif

(Should by "Lu", btw).

How you checked it prints correctly?  There are Googlable reports of
people using "%lld" on Mingw saying that it doesn't print large 64-bit
values correctly, because it truncates them to 32 bits, and trying
"%I64u" and it works.  Possibly due to Mingw programs calling
Microsoft's C library, therefore being subject to Windowsness.

The same _could_ happen with "%Ld" or "%Lu", if Microsoft hasn't
implemented that as 64-bit.

-- Jamie