UdpSocket::connect fails on unspecified host

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1

This code fails at runtime. Only on MacOS.
It would be nice to have a clearer error rather than "Invalid Argument" in this double colon IPv6 address case.

Source: bevy_simple_networking/simple_client.rs at main · bacongobbler/bevy_simple_networking · GitHub

use std::net::{SocketAddr, UdpSocket};

fn main() {
    // Because of this
    let bind_addr: SocketAddr = "[::]:8000".parse().expect("could not parse addr");

    let remote_addr: SocketAddr = "0.0.0.0:8001".parse().expect("could not parse addr");
    dbg!(remote_addr, bind_addr);

    let socket = dbg!(UdpSocket::bind(bind_addr).expect("could not bind socket"));

    // Panics there
    socket
        .connect(remote_addr)
        .expect("could not connect to server");

    dbg!(socket);
}

$ rustc main.rs
$ ./main
[main.rs:13] remote_addr = 0.0.0.0:8001
[main.rs:13] bind_addr = [::]:8000
[main.rs:15] UdpSocket::bind(bind_addr).expect("could not bind socket") = UdpSocket {
    addr: [::]:8000,
    fd: 3,
}
thread 'main' panicked at 'could not connect to server: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }', main.rs:20:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Solution:
It seems that on MacOS you can't connect to IPv4 address if you are bound to IPv6 and vice versa.
"[::]:8000" is IPv6, but "0.0.0.0:8001" is IPv4. So please use this check from tokio:

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