configure: error: invalid feature name: multilib--with-gmp=/home/xwx/exper/exp5/gcc-build/gmp-5.0.0

This error message indicates that the configuration script encountered an invalid feature name related to the GNU Multiple Precision Arithmetic Library (GMP). Specifically, it appears that the script is trying to use the "multilib" feature with an incorrect argument for the location of the GMP library.

To resolve this error, you may need to check the configuration options that you are using for your build of GCC and ensure that they are correct. In particular, you should double-check any options related to GMP and ensure that the paths and arguments are correct.

You may also want to consult the GCC documentation or seek help from the GCC community or support team for further assistance with configuring your build.