error[E0277]: `std::rc::Rc>` cannot be sent between threads safely --> $DIR/auto-trait-leak2.rs:13:5 | LL | fn send(_: T) {} | ---- ---- required by this bound in `send` ... LL | send(before()); | ^^^^ `std::rc::Rc>` cannot be sent between threads safely | = help: within `impl std::ops::Fn<(i32,)>`, the trait `std::marker::Send` is not implemented for `std::rc::Rc>` = note: required because it appears within the type `[closure@$DIR/auto-trait-leak2.rs:7:5: 7:22 p:std::rc::Rc>]` = note: required because it appears within the type `impl std::ops::Fn<(i32,)>` error[E0277]: `std::rc::Rc>` cannot be sent between threads safely --> $DIR/auto-trait-leak2.rs:16:5 | LL | fn send(_: T) {} | ---- ---- required by this bound in `send` ... LL | send(after()); | ^^^^ `std::rc::Rc>` cannot be sent between threads safely | = help: within `impl std::ops::Fn<(i32,)>`, the trait `std::marker::Send` is not implemented for `std::rc::Rc>` = note: required because it appears within the type `[closure@$DIR/auto-trait-leak2.rs:24:5: 24:22 p:std::rc::Rc>]` = note: required because it appears within the type `impl std::ops::Fn<(i32,)>` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0277`.