$ cargo check Checking hello v0.1.0 (file:///projects/hello) error[E0507]: cannot move out of `worker.thread` which is behind a mutable reference --> src/lib.rs:52:13 | 52 | worker.thread.join().unwrap(); | ^^^^^^^^^^^^^ ------ `worker.thread` moved due to this method call | | | move occurs because `worker.thread` has type `JoinHandle<()>`, which does not implement the `Copy` trait | note: `JoinHandle::::join` takes ownership of the receiver `self`, which moves `worker.thread` --> /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/std/src/thread/mod.rs:1657:17 For more information about this error, try `rustc --explain E0507`. error: could not compile `hello` (lib) due to 1 previous error