That's exactly how Typescript works. The point is that the type-safety checks are done at transpilation time, and that step fails if you've violated them. So I'

That's exactly how Typescript works. The point is that the type-safety checks are done at transpilation time, and that step fails if you've violated them. So I'm assuming something similar for cppfront - it will fail to transpile if your code doesn't pass the additional safety checks.