cet-is

Boost 1.65.0 has been out for a couple of weeks, but the homebrew recipe has only just been updated to include it. This recipe includes a couple of OS X-specific tweaks to the build that we should look at incorporating.

Also, in the light of recent experience applying a patch to the Boost 1.64.0 build, we should look at ways of eliminating the double source untar -- once for the build and once for the debug source. Options are:

1. Stop shipping the source.
2. Examine what (if anything) happens to the source tree in terms of changes during a build. If the answer is, "nothing," then we should look at building out-of-source, which is apparently possible using either options to the b2 invocation or tweaks to the build.jam build configuration file. If the answer is, "something architecture-specific," then we should look again at the whole idea of including debug source in an architecture-independent location (see option 1).