Rust安全之数值

数值溢出

编译通过,运行失败
cargo run 1

fn main() {
    let mut arg = std::env::args()
        .skip(1)
        .map(|x| x.parse::<i32>().unwrap())
        .next()
        .unwrap();
    let m_i = i32::MAX - 1;
    let a = m_i + arg;

    println!("{:?}", a);
}

thread 'main' panicked at 'attempt to add with overflow', src\bin\rssh3.rs:13:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: process didn't exit successfully: `target\debug\rssh3.exe 1` (exit code: 101)

编译不通过

fn main() {
    let m_i = i32::MAX;
    let a = m_i + 1;

    println!("{:?}", a);
}

输出

error: this arithmetic operation will overflow
 --> src\bin\rssh3.rs:9:13
  |
9 |     let a = m_i + 1;
  |             ^^^^^^^ attempt to compute `i32::MAX + 1_i32`, which would overflow
  |
  = note: `#[deny(arithmetic_overflow)]` on by default

warning: `datetime-util` (bin "rssh3") generated 4 warnings
error: could not compile `datetime-util` due to previous error; 4 warnings emitted