http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46319
--- Comment #3 from Dave Korn <davek at gcc dot gnu.org> 2010-11-05 22:59:04 UTC --- When I tried running these tests in a pre-existing build tree, plugin_default_version_check failed because the datestamps don't match up: (gdb) p gcc_version[0] $5 = {basever = 0x1029fe8 "4.6.0", datestamp = 0x1029fee "20101103", devphase = 0x1029ff7 "experimental", revision = 0x1143f30 "", configuration_arguments = 0xd2d2c0 "/n/10/davek/gcc/gcc/configure --prefix=/n/ 10/davek/gcc --with-mpfr=/opt/cfarm/mpfr-2.4.1 --with-gmp=/opt/cfarm/gmp-4.2.4 - -with-mpc=/opt/cfarm/mpc-0.8 --with-libelf=/n/10/davek/usr --enable-bootstrap ". ..} (gdb) p plugin_version[0] $6 = {basever = 0x7ffff7567d29 "4.6.0", datestamp = 0x7ffff7567d2f "20101105", devphase = 0x7ffff7567d38 "experimental", revision = 0x7ffff7567e28 "", configuration_arguments = 0x7ffff7566720 "/n/10/davek/gcc/gcc/configure --pref ix=/n/10/davek/gcc --with-mpfr=/opt/cfarm/mpfr-2.4.1 --with-gmp=/opt/cfarm/gmp-4 .2.4 --with-mpc=/opt/cfarm/mpc-0.8 --with-libelf=/n/10/davek/usr --enable-bootst rap "...} (gdb) This will happen if $objdir/gcc/plugin-version.h or $objdir/gcc/configargs.h has been regenerated for any reason in between building the compiler and running the test. Can you tell if this may have happened in your case?