https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117970
--- Comment #6 from Lewis Hyatt <lhyatt at gcc dot gnu.org> --- I can reproduce that failure using your configuration to make cross compilers on an x86-64 host. The tests pass when a single arch is configured, there are just problems with multilib configuration. They also pass with the multilib setup when run from the installed compiler, they just fail when the test is run from the build directory with an alternate arch using --target_board. It has to do with finding different libstdc++ headers I think. Things that affect the numerical value of locations can trigger it, which is why e.g. the -std=c++23 vs -std=c++20 makes a difference, as well as the change to 64-bit location_t. I'm not sure yet beyond that.
