Thanks for the reply.  I used MSVC itself this time rather than Clang, though.  And standards-conformance mode is turned on with "/permissive-" since nonconformance mode is turned on with "/permissive".  

By the way, when I had Boost 1.68.0 and I tried to build Jinja2Cpp with that, CMake was able to find it.  But for some reason it can't find 1.69.0.