You are misunderstanding the thread, I just mentioned some of the languages I like (still waiting for Go's generics), and the comment I was replying to made an assert about an implementation that uses cgo.

Both of us are dismissing the assertion that "Arenas are, however, unfeasible to implement in Go because it is a garbage collected language."

You can do manually memory allocation via a syscall into the host OS, use unsafe to cast memory blocks to the types that you want and then clean it all up with defer, assuming the arena is only usable inside a lexical region, otherwise extra care is needed to avoid leaks.