[AnthonyMouse]

It's not a question of regulations. You either need to use the old library with the new compiler or the new library with the old compiler.

But the old one is crufty and barely maintained and nobody wants to touch it, and the new one is only using one feature of the new version of Boost, so it's a easier to blacklist the newer version of Boost than to overhaul all the old code. But is that what we wanted to cause?

Moreover, with widely used core libraries like this, that sort of thing happens repeatedly, and now the downstream users have to do work they wouldn't have had to do if compatibility was maintained. At scale probably a lot more work than it would be for the widely used thing to maintain compatibility. That seems bad.