Swift ARC Problem

arc-test.swift

class A {
    var values:[Int] = [];
}

func append1(inout a:A) {
    let n = a.values.count;
    a.values.append(n);
}

func append2(inout a:A) {
    let b = a.values;
    let n = b.count;
    a.values.append(n);
}

func test() {
    var a = A();

    // Using 'append1' is linear.
    // Whereas, 'append2' is quadratic.
    for _ in 0..<10000000 {
        append2(&a);
    }

    print(a.values.count);
}

test();