Right, so the full workflow is now OK with gcc 13 after:

• pinning OSRM to current HEAD with hard-coded commit SHA in the GA workflow;
• adding -DCMAKE_CXX_FLAGS="-Wno-array-bounds to the OSRM build command.

Our next problem is that we do not really check for clang 18 due to a known issue reported in #1098. I'll try to include the changes suggested in #1101 here in order to try and do everything at once.

My expectation is that we'll have everything running then except the OSRM clang 18 build, which we can then focus on.

As expected, building OSRM on current master fails with clang 18. The good news is that it's OK with clang 16 and 17 which I just tested locally, so the upgrade (and OS update) is still possible even if we have to wait to be using clang 18.