I was attempting to add quick-xml to the Rust serializer benchmarks and discovered that one of the complex benchmarks serialized incorrectly, resulting in errors on deserialization. The benchmark in question is the "minecraft savedata" benchmark.

I minimized it so it's less unwieldy. Here's a test case.

const RECIPES: [&'static str; 8] = [
    "pickaxe",
    "torch",
    "bow",
    "crafting table",
    "furnace",
    "shears",
    "arrow",
    "tnt",
];

#[derive(serde::Deserialize, serde::Serialize)]
pub struct RecipeBook {
    pub recipes: Vec<String>,
}

#[test]
fn test_fail_serialize() {
    let recipe_book = RecipeBook {
        recipes: RECIPES.iter().map(|s| s.to_string()).collect(),
    };

    let serialized = to_string(&recipe_book).unwrap();

    println!("{}", serialized);
    let deserialized: RecipeBook = from_str(&serialized).unwrap();
}

Prints the following when tests are run:

---- test_fail_serialize stdout ----
<RecipeBook recipes="pickaxetorchbowcrafting tablefurnaceshearsarrowtnt"/>
thread 'test_fail_serialize' panicked at 'called `Result::unwrap()` on an `Err` value: Custom("invalid type: string \"pickaxetorchbowcrafting tablefurnaceshearsarrowtnt\", expected a sequence")', tests/serde_roundtrip.rs:55:58
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The problem is that recipes: Vec<String> and to_be_displayed: Vec<String> are being serialized into one long concatenated string and then assigned to an attribute of a self-closing element, rather than being serialized to a list of inner elements. Deserialize does the correct thing and expects a list of strings.