Where’s the problem for context-freeness here? Just have two copies of every statement production, one that doesn’t allow for case labels and one that does, have function bodies start as the former and switch bodies unconditionally switch to the latter. It’d be thoroughly unpleasant to deal with in an implementation and not very helpful for the eventual user, but as a pure existence proof I don’t see any problems.
Yes, that's true. Maybe I should say that it's effectively context-sensitive. In any case, the grammar as specified by the standard is context-free and the restriction of where case labels can occur is a separate semantic requirement.
