7.8 blockers

Yup. Handling both cases in the code is really simply, the difficult bit is communicating the compatibility level from compliation to runtime. In the case of functions, this can be done by making a compatibility function func_76 which is substituted for the regular function in a compatibility namespace. But since sscanf is an operator, I think we would need to add a special bytecode for the compatibility version. Or can someone come up with a simpler solution?

Hmm...

Let the compiler add an implicit call to a format conversion function on the first argument in compat mode? The question is how complicated it would be to write such a function.