[skybrian]

The root cause is wanting to support fixed-size array types in structs, which means nothing can require initialization and everything needs a zero value. The caller can just modify every field directly.

This is sort of like how network protocols can’t statically guarantee enums are valid either. When sending bits over the wire, you can send any bits you like. There can be “values reserved for future use,” but to deny their use, you need a runtime check.

A similar solution works in Go. A runtime check in a constructor function will fix it. The enum’s value would need to be returned as an unexported field in a struct, which is the only way to guarantee that it’s not writable, except by copying it from another valid value.

I don’t see a particular reason why Go couldn’t make this easier.