This seems to be a persistent source of confusion. Escape analysis is just an optimization. You don't need to think about it to understand why your Go code behaves the way it does. Just imagine that everything is allocated on the heap and you won't have any surprises.

If the functions get inlined (which they might if they're small enough), then the code won't even need to allocate on heap! That's a kind of optimisation that's not really possible without transparent escape analysis.

Go is returning a copy of the slice, in the same way that C would return a copy of an int or struct if you returned it. The danger of C behaviour in this instance is that a stack allocated array decays into a pointer which points to the deallocated memory. Otherwise the behaviour is pretty similar between the languages.

If the variable was defined in the calling function itself, and a pointer was passed, I guess the variable will still be in the heap?