From dankwiki
9 bytes added ,  22:18, 6 January 2010
off to dig through gcc source....</pre>Nonetheless, this is a poorly-documented gcc-specific method; best to always provide -D_REENTRANT explicitly. -D_REENTRANT and other preprocessor directives which affect code selection should always precede -include options to gcc, ie:<pre>gcc -D_REENTRANT -I/usr/local -include pthread.h ...</pre>
On FreeBSD's libc (and also possibly with regard to other third-part libraries), it's also necessary to define _THREAD_SAFE, as evidenced below (furthermore, you need _POSIX_PTHREAD_SEMANTICS and _P1003_1B_VISIBLE for reasons I determined long ago and have since forgotten, see the [[GNU make|make]] snippet below --''dank''):<pre>Newsgroups: sys.research.subversion.repper
From: Nick Black <>
Subject: Re: [repper-304] REENTRANT is required by POSIX for any code using pthr