Unchecked integer range

[BratSinot]

Greetings!

config lib is casting all integers like explicit type conversion through as. Such behaviour by design, or this is an error?

use config::Config;

fn main() {
    let mut conf = Config::new();

    conf.merge(config::File::from_str(
        r#"
        [server]
        port = 66000
        "#,
        config::FileFormat::Toml,
    ))
    .unwrap();

    let port: u16 = conf.get("server.port").unwrap();

    println!("{}", port); // output is 464
}

[BratSinot]

Maybe duplicate of this #93.

[matthiasbeyer]

Yes, this is actually a limitation.

The problem is here that the format (toml in this case, but others apply here as well) does not define the datatype (besides "Number"). By specifying let port: u16 in your code, the value is inferred to be u16 and the library just assumes that the number is actually a 16 bit unsigned integer.

We cannot do much here, on the library side of things, actually (or I'm wrong and someone comes up with something clever...).

We need you to know about your data, so you have to make sure that you ask for a u32 here and all will be fine I guess.

[BratSinot]

Yes, this is actually a limitation.

The problem is here that the format (toml in this case, but others apply here as well) does not define the datatype (besides "Number"). By specifying let port: u16 in your code, the value is inferred to be u16 and the library just assumes that the number is actually a 16 bit unsigned integer.

We cannot do much here, on the library side of things, actually (or I'm wrong and someone comes up with something clever...).

We need you to know about your data, so you have to make sure that you ask for a u32 here and all will be fine I guess.

Thanks for answer!
For now I'm using this workaround:

    let port: u16 = conf
        .get_int("server.port")
        .unwrap()
        .try_into() // here
        .unwrap();

or this:

    let port = conf
        .get_string("server.port")
        .unwrap()
        .parse::<u16>()
        .unwrap();

[matthiasbeyer]

Okay, I'm closing this therefore, feel free to ping me if you have more questions on the matter! 😄