Llvm in FreeBSD 12.3 gives several compile errors.
One example:
src/mongo/s/sharding_initialization.cpp:171:49: error: no viable constructor or deduction guide for deduction of template arguments of 'weak_ptr'
connPoolOptions.controllerFactory = [srwp = std::weak_ptr(srsp)] {
http://beefy6.nyi.freebsd.org/data/123amd64-default/0116f5c59197/logs/errors/mongodb60-6.0.2.log
PR: 266587