libc++'s std::pair always has a default constructor, and it is ill-formed
when the members are not default constructible. We need it to be SFINAE
friendly. See https://llvm.org/bugs/show_bug.cgi?id=21917.
- Extend the Quick Start with more small examples, and then the large
switchAny example.
- Add clarifying remarks right in front of the CheatSheet for skimmers.
Damn skimmers.
- Benchmark the compile-time of creating std::array