https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100017
--- Comment #57 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I don't see how the patch could be correct. Looking at RAW_CXX_FOR_TARGET in configure, I see: (starting with the line you're proposing to change): RAW_CXX_FOR_TARGET="$CXX_FOR_TARGET" ... { $as_echo "$as_me:${as_lineno-$LINENO}: checking where to find the target c++ for libstdc++" >&5 $as_echo_n "checking where to find the target c++ for libstdc++... " >&6; } if test "x${build}" != "x${host}" ; then if expr "x$RAW_CXX_FOR_TARGET" : "x/" > /dev/null; then # We already found the complete path ac_dir=`dirname $RAW_CXX_FOR_TARGET` { $as_echo "$as_me:${as_lineno-$LINENO}: result: pre-installed in $ac_dir" >&5 $as_echo "pre-installed in $ac_dir" >&6; } else # Canadian cross, just use what we found { $as_echo "$as_me:${as_lineno-$LINENO}: result: pre-installed" >&5 $as_echo "pre-installed" >&6; } fi else So, if CXX_FOR_TARGET starts with /, e.g. /opt/gcc-11.1/bin/g++ , then the above will use dirname /opt/gcc-11.1/bin/g++ and set ac_dir to /opt/gcc-11.1/bin But with the proposed change, $RAW_CXX_FOR_TARGET will be /opt/gcc-11.1/bin/g++ -nostdinc++ and dirname will fail miserably and not set ac_dir to anything: dirname /opt/gcc-11.1/bin/g++ -nostdinc++ dirname: invalid option -- 'n' Try 'dirname --help' for more information.