Mismatched types not throwing error?

[winterqt]

In the following snippet:

use dbus::blocking::Connection;
use std::time::Duration;

fn main() {
    let conn = Connection::new_system().unwrap();

    let proxy = conn.with_proxy(
        "org.freedesktop.systemd1",
        "/org/freedesktop/systemd1",
        Duration::from_secs(5),
    );

    let (res,): (Vec<(u32,)>,) = proxy
        .method_call("org.freedesktop.systemd1.Manager", "ListUnits", ())
        .unwrap();

    dbg!(res);
}

where the struct type is actually ssssssouso, I'd expect an error (since a String is trying to be parsed into a u32). Instead, res is equal to [].

Why is this?

[winterqt]

Figured it out: this seems to be a limitation Vec's implementation of Get::get:

impl<'a, T: Arg + Get<'a>> Get<'a> for Vec<T> {
    fn get(i: &mut Iter<'a>) -> Option<Self> {
        <Array<T, Iter<'a>>>::get(i).map(|a| a.collect())
    }
}

As far as I can tell, as long as the return type is an array, this will return Some, leading to no error being thrown by Iter::read.

[diwic]

There seems to be a todo item for exactly this:

impl<'a, T: Arg + Get<'a>> Get<'a> for Array<'a, T, Iter<'a>> {
    fn get(i: &mut Iter<'a>) -> Option<Array<'a, T, Iter<'a>>> {
        i.recurse(Self::ARG_TYPE).map(|si| Array(si, PhantomData))
        // TODO: Verify full element signature?
    }
}

PRs welcome. :-)