“Applying this technique to protobuf parsing has yielded amazing results: we have managed to demonstrate protobuf parsing at over 2GB/s, more than double the previous state of the art.”
Functional programmers have asked for guaranteed tail calls for decades. They finally landed in Clang because a Google engineer needed faster protobuf parsing. The catch is that musttail is a nonstandard extension, so portable code can’t count on it. Interpreters in C could all get faster. Most will wait years for it to reach their compilers.