Rust: Proof of Concept, Not Replacement(files.neoon.com)

   error[E0382]: use of moved value: `results`
   --> src/main.rs:30:22
      |
   22 |     let results = Arc::new(Mutex::new(Vec::new()));
      |         ------- move occurs because `results` has type `Arc<std::sync::Mutex<Vec<i32>>>`, which does not implement the `Copy` trait
   ...
   28 |     for i in 0..20 {
      |     -------------- inside of this loop
   29 |         // let results = Arc::clone(&results);
   30 |         pool.execute(move || {
      |                      ^^^^^^^ value moved into closure here, in previous iteration of loop
   31 |             let mut r = results.lock().unwrap();
      |                         ------- use occurs due to use in closure
      |
   help: consider moving the expression out of the loop so it is only moved once
      |
   28 ~     let mut value = results.lock();
   29 ~     for i in 0..20 {
   30 |         // let results = Arc::clone(&results);
   31 |         pool.execute(move || {
   32 ~             let mut r = value.unwrap();
      |
   help: consider cloning the value before moving it into the closure
      |
   30 ~         let value = results.clone();
   31 ~         pool.execute(move || {
   32 ~             let mut r = value.lock().unwrap();
      |

   error[E0277]: `std::sync::MutexGuard<'_, Vec<i32>>` cannot be sent between threads safely
      --> src/main.rs:30:22
      |
   30 |           pool.execute(move || {
      |                ------- ^------
      |                |       |
      |  ______________|_______within this `{closure@src/main.rs:30:22: 30:29}`
      | |              |
      | |              required by a bound introduced by this call
   31 | |             let mut r = results.unwrap();
   32 | |             r.push(i);
   33 | |         });
      | |_________^ `std::sync::MutexGuard<'_, Vec<i32>>` cannot be sent between threads safely
      |
      = help: within `{closure@src/main.rs:30:22: 30:29}`, the trait `Send` is not implemented for `std::sync::MutexGuard<'_, Vec<i32>>`
   note: required because it appears within the type `Result<std::sync::MutexGuard<'_, Vec<i32>>, PoisonError<std::sync::MutexGuard<'_, Vec<i32>>>>`
      --> /playground/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:550:10
      |
   550 | pub enum Result<T, E> {
      |          ^^^^^^
   note: required because it's used within this closure
      --> src/main.rs:30:22
      |
   30 |         pool.execute(move || {
      |                      ^^^^^^^
   note: required by a bound in `ThreadPool::execute`
      --> src/main.rs:15:23
      |
   13 |     fn execute<F>(&self, f: F)
      |        ------- required by a bound in this associated function
   14 |     where
   15 |         F: FnOnce() + Send + 'static,
      |                       ^^^^ required by this bound in `ThreadPool::execute`

   // FIXME: We could check that the call's *parent* takes `&mut val` to make the
   // suggestion more targeted to the `mk_iter(val).next()` case. Maybe do that only to
   // check for whether to suggest `let value` or `let mut value`.