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".
What Paul was suggesting is to forget about the conformance-mode and just pick a standard (C++14, the default or C++17), as you are just making your own life difficult by imposing conformance, while Boost has many well tested work-arounds for those non-conformant constructs in MSVC. The imposed conformance itself might also interact badly with those work-arounds.
degski