Is working past the end of a slice idiomatic?

Question

I was reading through Go\'s compress/flate package, and I found this odd piece of code [1]:

n := int32(len(list))
list = list[0 : n+1]
list[n] = max         


        

Answer 1

It cannot be a run time exception because the language specification prescribes that the upper limit of the slice operation is the capacity of the slice, not its length.