Proc macro rename attribute ignores trailing content

[dnaka91]

I just had an interesting bug where I made a spelling error for the rename attribute. When I discovered it, I thought the proc macro could probably catch this.

What I did by accident was:

#[derive(Deserialize)]
struct SomeStruct {
    #[serde(rename = ""value)] // This should have been `rename = "value"`
    pub a: i32
} 

The second " went in front of the rename value, instead of behind. Apparently, the proc macro accepts this input and only takes "", ignoring the value. If there is a space between it (like #[serde(rename = "" value)]), it'll fail properly, telling about the unknown attribute value.