1 error[E0225]: only auto traits can be used as additional traits in a trait object
4 LL | let _: Box<dyn std::io::Read + std::io::Write>;
5 | ------------- ^^^^^^^^^^^^^^ additional non-auto trait
9 = help: consider creating a new trait with all of these as super-traits and using that trait here instead: `trait NewTrait: std::io::Read + std::io::Write {}`
10 = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
12 error[E0225]: only auto traits can be used as additional traits in a trait object
13 --> $DIR/E0225.rs:8:20
15 LL | trait Foo = std::io::Read + std::io::Write;
16 | ------------- -------------- additional non-auto trait
18 | first non-auto trait
20 LL | let _: Box<dyn Foo>;
23 | trait alias used in trait object type (additional use)
24 | trait alias used in trait object type (first use)
26 = help: consider creating a new trait with all of these as super-traits and using that trait here instead: `trait NewTrait: std::io::Read + std::io::Write {}`
27 = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
29 error: aborting due to 2 previous errors
31 For more information about this error, try `rustc --explain E0225`.