Document (more prominently?) that serde_json allows sequences to be deserialized into structs

[tbu-]

Last time I saw this was https://old.reddit.com/r/rust/comments/1332t9b/ji7oo8m/, but I've also seen it earlier and found it surprising both times.

Basically both {"hello": "test", "value": 42} (expected) and ["test", 42] deserialize perfectly fine into the following struct:

#[derive(Serialize, Deserialize)]
pub struct HelloParams {
    hello: String, 
    value: i32,
}

Since this is not mentioned anywhere, this can accidentally become a used API when serde is used to parse JSON (Hyrum's law).

It would be nice if this could be featured somewhere prominently in the docs. I couldn't actually find it there, even looking for it.

[Mingun]

Probably serde_json should not call visit_seq if deserialize_map / deserialize_struct was requested by the type. Then deserialization structs from JSON arrays would be impossible. That also can be a configurable behavior of serde_json deserializer.

[Mingun]

Actually, this is duplicate of #1587.

[tbu-]

I don't see how this is a duplicate, @oli-obk. This is about documenting behavior of serde_json, not about changing it. The other issue asks for behavioral changes that are likely backward incompatible and thus unlikely to happen.