Andrew Pardoe asked me to post his reply:
<aside> We always urged Microsoft to test their releases against Boost. For update 3 expression SFINAE, they did exactly that. Thanks to Microsoft's Andrew Pardoe for coordinated the effort and to Xiang Fan for running the tests and tracking down the reason for each test failure. An undocumented Boost.Config macro BOOST_MSVC_SFINAE_EXPR to support their testing. The approach was to run tests for all libraries with the normal test setup, and then run again with BOOST_MSVC_SFINAE_EXPR defined. If the problem was with the Boost library, Xiang then reported it to me. I need to review a long series of email exchanges with him to make sure I alerted library maintainers to any Boost problems. </aside>
Thank you, Beman, for the kind words. As we work to make MSVC completely standards-conforming we’ve been focusing on the libraries that our developers (both inside and outside of Microsoft) want to use. Not surprisingly, Boost is on the top of that list. If any of the Boost maintainers need to coordinate with MSVC please don’t hesitate to reach out to me. We’ll continue to prioritize your issues so that we can get—and keep—Boost compiling on MSVC without special-casing conditional code.