http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40411
bruno at clisp dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bruno at clisp dot org --- Comment #17 from bruno at clisp dot org 2010-12-26 18:06:15 UTC --- Note that the use of values-xpg6.o leads to unexpected behaviour when considering shared libraries: 1) The behaviour of a shared library also depends on whether the executable is linked with or without values-xpg6.o. The author of the shared library may not expect this and may not have tested in this situation. 2) The behaviour of an executable also depends on whether some of the shared libraries was built with values-xpg6.o. The author of the program may not expect this. This leads to real bugs: <http://lists.gnu.org/archive/html/autoconf/2010-02/msg00013.html> More details in <http://lists.gnu.org/archive/html/autoconf/2010-12/msg00059.html> For this reason, I would find it bad if "gcc -std=c99" or "gcc -std=gnu99" would cause values-xpg6.o to be included in the link. Please close this issue as "Won't fix". Programs which wish to have POSIX compliant behaviour of system functions can use GNU gnulib; it doesn't rely on values-xpg6.o.