Reading enums in Rust can lead to UB in case of incorrect file content

[VeaaC]

Unlike C/C++ Rust enums are exhaustive: All possible values need to be explicitly mentioned.

That means that casting from the underlying type (e.g. 9 bit integer) to the enumeration can cause UB if the value stored in flatdata does not exist in the enumeration (e.g. corrupted file, etc).

Rust doesn't currently support C-like enums. This means that our options are a bit limited. Some ideas:

• Create enum with an additional (hidden?) field Unknown, and check in reader (speed impact?)
• Check enum values every time data is read and panic (speed impact)
• Do not expose as enum, but newtype integer plus constants
• If speed is impacted a raw reading function might be needed for fast access