Well the "workaround" (if you want to call it that) in [the MacPorts patch](https://trac.macports.org/attachment/ticket/40863/bonniexx.diff) was to disable compilation with clang; bonnie++ still compiles fine with gcc. I can't find an "official" issue tracker for bonnie++, else I'd file a bug upstream (per brew's guidelines), but this seems to be an acceptable workaround until the package is updated/patched to compile with clang. I'm not a programmer or I'd write a patch myself :-)