// example4.go
package main

import "math/rand"

func fa2() {
    s := []int{0, 1, 2, 3, 4, 5, 6}
    index := rand.Intn(7)
    _ = s[index:] // line 9: bounds check 
    _ = s[:index] // line 10: bounds check eliminatd!
}

func fb2(s []int, index int) {
    _ = s[index:] // line 14: bounds check
    _ = s[:index] // line 15: bounds check // not clever enough?
}

func fc2() {
    s := []int{0, 1, 2, 3, 4, 5, 6}
    s = s[:4]
    index := rand.Intn(7)
    _ = s[index:] // line 22: bounds check 
    _ = s[:index] // line 23: bounds check eliminatd!
}

func main() {}

go build -gcflags="-d=ssa/check_bce/debug=1" example4.go
# command-line-arguments
./11.go:9: Found IsSliceInBounds
./11.go:14: Found IsSliceInBounds
./11.go:15: Found IsSliceInBounds
./11.go:22: Found IsSliceInBounds