Although this question is not proper to this group, please forgive me.
I can't find out the right group, not mailing list, for gcc. :(
Anyway... I should use -D_XOPEN_SOURCE=500 options when compiling
a program that uses POSIX rwlock. It seems that -D_GNU_SOURCE do well.
But, with D_XOPEN_SOURCE=500 option, u_long is no more defined.
After look into /usr/include/sys/types.h I came to know that u_long
is defined only if __USE_BSD is defined.
Then, _XOPEN_SOURCE=500 undefine, or doesn't define, __USE_BSD?
If so, what does this option mean?
And, when I use -D_GNU_SOURCE u_long is defined. What's the difference
between _GNU_SOURCE and _XOPEN_SOURCE=500?