Deserializing into a type with an unsigned integer doesn't give the expected result

[repnop]

Minimal example:

main.rs

use config::Config;
use serde::Deserialize;

#[derive(Deserialize)]
struct Foo {
    bar: u64,
}

fn main() {
    let mut settings = Config::new();
    settings.merge(config::File::with_name("test")).unwrap();
    
    let foo: Foo = settings.try_into().unwrap();
    println!("{}", foo.bar);
}

test.toml

bar = -1

Running this code produces 18446744073709551615 instead of erroring that the value was outside of the range of u64

[jcrevier]

Additionally, related to this is that values greater than i64::max_value() will fail to de-serialize into a u64. The problem seems to be the Deserialize implementation uses the into_int() method that converts everything into i64 then casts back to the needed type.

[kesyog]

Updated example:

use config::Config;
use serde::Deserialize;

#[derive(Deserialize)]
struct Foo {
    bar: u64,
}

fn main() {
    let settings = Config::builder()
        .add_source(config::File::with_name("test"))
        .build()
        .unwrap();

    let foo: Foo = settings.try_deserialize().unwrap();
    println!("{}", foo.bar);
}

[kesyog]

Fixed on master by #353