FreeFox wrote:So I can't really see what harm it does to document it in FB, given the succinct way @fxm has done it.
The thing is that undocumented means in general "don't use" while as soon as something is documented (and not additionally marked as deprecated, obsolete, ...) it means that it can be used.
Additionally, if it's not documented it is easy to change (for the compiler devs; like e.g. removing that legacy syntax) because they don't have to care about compatibility (the programmer has to solve problems if he/she's using undocumented stuff). As soon as it's documented the compiler devs are responsible for maintaining backward compatibility and/or providing a migration path.
And in this particular case I'd opt for "don't use", so I'd mark it as obsolete/outdated/deprecated/... at least. Maybe "-lang qb" could be an exception where such legacy constructs could be still allowed.