With glibc 2.4, the treatment of _POSIX_C_SOURCE changed. However, an important comment in <features.h> describing the behaviour was not changed. In the sentence: "If none of these are defined, the default is to have... and _POSIX_C_SOURCE set to 199506L." the number should be "200112L".
Fixed in cvs.
Subject: Bug 3632 CVSROOT: /cvs/glibc Module name: libc Branch: glibc-2_5-branch Changes by: jakub@sourceware.org 2007-01-12 17:16:44 Modified files: . : ChangeLog include : features.h Log message: [BZ #3632] * include/features.h: Fix comment about default value for _POSIX_C_SOURCE. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/libc/ChangeLog.diff?cvsroot=glibc&only_with_tag=glibc-2_5-branch&r1=1.10362.2.19&r2=1.10362.2.20 http://sourceware.org/cgi-bin/cvsweb.cgi/libc/include/features.h.diff?cvsroot=glibc&only_with_tag=glibc-2_5-branch&r1=1.44&r2=1.44.2.1