「奇技淫巧」利用断言进行编译器优化 about tao-of-rust-codes HOT 2 OPEN

fn g(a: &[u8], v: usize) -> u32 {
    if v >= a.len() {
        panic!("wrong");
    }
    unsafe { *a.get_unchecked(v) as u32 }
}
pub fn foo(a: &[u8]) -> u32 {
    g(a, 0) + g(a, 1) + g(a, 2) + g(a, 3)
}