In the go protobuf code, a pattern is used to statically prevent
comparable structs by embedding:
```
type DoNotCompare [0]func()
type message struct {
DoNotCompare
data *uint32
}
```
Previously, sizezof(message{}) is 2 words large, but it only needs to be
1 byte. Making it be 1 byte allows protobufs to compile slightly more
(though not all the way).
4c7449efe5