package recursiveescapebug

const debugMode = false

func A() int {
        b := 0
        B(&b, 5)
        return b
}

func B(state *int, recursions int) {
        switch recursions {
        case 0:
        default:
                *state++

                if debugMode {
                        // this is dead code, removed by the optimizer.
                        // however, its presence causes the compiler to consider B's state argument to escape.
                        panic(state)
                }

                B(state, recursions-1)
        }
}

$ go build -gcflags='-live -m'
# _/home/username/testthing
./recursiveescapebug.go:11: leaking param: state
./recursiveescapebug.go:6: moved to heap: b
./recursiveescapebug.go:7: &b escapes to heap
./recursiveescapebug.go:7: live at call to B: &b
./recursiveescapebug.go:11: live at entry to B: state
./recursiveescapebug.go:23: live at call to B: state