One surprise is that the following loop will print false (now it prints true).

    for i, p := 0, (*int)(nil); p == nil; print(p == &i) {
        p = &i
    }

Another surprise is that the value a in the following loop will be duplicated twice in each loop step (now it never gets duplicated).

    func foo(constFunc func(*[100000]int)) {
        for a, i := [100000]int{}, 0; i < len(a); i++ {
            constFunc(&a)
        }
    }