error[E0277]: `Rc` cannot be sent between threads safely --> $DIR/kindck-nonsendable-1.rs:9:9 | LL | bar(move|| foo(x)); | --- ------^^^^^^^ | | | | | `Rc` cannot be sent between threads safely | | within this `[closure@$DIR/kindck-nonsendable-1.rs:9:9: 9:15]` | required by a bound introduced by this call | = help: within `[closure@$DIR/kindck-nonsendable-1.rs:9:9: 9:15]`, the trait `Send` is not implemented for `Rc` note: required because it's used within this closure --> $DIR/kindck-nonsendable-1.rs:9:9 | LL | bar(move|| foo(x)); | ^^^^^^ note: required by a bound in `bar` --> $DIR/kindck-nonsendable-1.rs:5:21 | LL | fn bar(_: F) { } | ^^^^ required by this bound in `bar` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.