There’s not any way to know when the version needs to be bumped or what should happen when there is a version mismatch. At best we can check the structure of the struct and crash if the data doesn’t match the schema, which is what structs currently do.
Until someone makes a sufficiently powerful type checking tool that could be run against both versions of the codebase the business of upgrading state in hot upgrades is going to be a manual process for the programmer to implement via the appropriate OTP callbacks. It’s a very challenging job, and I recall reading once that Ericsson spend as much time testing and developing their upgrades as their application code.
