1 Multiple types were used as bounds for a closure or trait object.
3 Erroneous code example:
7 let _: Box<dyn std::io::Read + std::io::Write>;
11 Rust does not currently support this.
13 Auto traits such as Send and Sync are an exception to this rule:
14 It's possible to have bounds of one non-builtin trait, plus any number of
15 auto traits. For example, the following compiles correctly:
19 let _: Box<dyn std::io::Read + Send + Sync>;