fn main() {
    let a=4u32;
    let b = &a as *const u32;
    let b = b as *mut u32;
    unsafe {
        test(&a, &mut *b);
        println!("{}",*b);
    }
}

fn test(a:&u32, b:&mut u32)->u32{
    if *a < 5 {
        *b+= 20;
    }//compiler assumes a variable cannot be
    //aliased if it's mutable, so it puts an else
    //here
    if *a > 10 {
        *b+=10;
    }
    *b //expected result: 34, actual result
    // (in release) 24
}