Fix 2 warnings when building with Clang

[rubenk]

attribute ((format (printf, 5, 6))) is supported by both GCC and Clang.

This fixes the following warnings:

In file included from log.c:33:
./log.h:42:48: warning: format attribute argument not supported: gnu_printf [-Wignored-attributes]
const char *fmt, ...) attribute ((format (gnu_printf, 5, 6)));
^
./log.h:43:73: warning: format attribute argument not supported: gnu_printf [-Wignored-attributes]
void log_write_direct(int log_id, const char *fmt, ...) attribute ((format (gnu_printf, 2, 3)));
^
2 warnings generated.

[karlheyes]

will need to looked at in more detail. The problem with this is, while it is correct, the problem case is, as ever, windows. The *printf routines on the windows platform are rubbish (although may be better in the latest update), so I use the mingw versions which really require the gnu_printf setting to enforce it, but likewise causes an issue on clang.

Can you verify if the following builds on the unpatched tree without issue, using clang

make CFLAGS="-Dgnu_printf=print"

if so then I can just force the same macro if GNUG is unset

karl.

[rubenk]

Ah yes, printf and Windows, I didn't consider that.
If I recall correctly mingw has a macro for this, __MINGW_PRINTF_FORMAT.

In any case, ./configure CC=clang CFLAGS="-Wall -g -O2 -Dgnu_printf=printf" && make silences the warning.