Cloning things which are Copy (such as u32) is futile and Clippy will tell you not to bother where it can see this is definitely Copy. If you don't use Clippy, I'd suggest trying it for a while.
Rc will be faster (if that matters to you) than Arc but it can't cross threads. (Safe) Rust will check you didn't get this wrong, so there's no danger but obviously knowing ahead of time avoids writing an Rc that you then need to be an Arc instead.
Sometimes it's tidier to write the borrow in the type of a pattern match e.g. if let Some(&foo) = ... Means you won't need to dereference foo inside the block.
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Cloning things which are Copy (such as u32) is futile and Clippy will tell you not to bother where it can see this is definitely Copy. If you don't use Clippy, I'd suggest trying it for a while.
Rc will be faster (if that matters to you) than Arc but it can't cross threads. (Safe) Rust will check you didn't get this wrong, so there's no danger but obviously knowing ahead of time avoids writing an Rc that you then need to be an Arc instead.
Sometimes it's tidier to write the borrow in the type of a pattern match e.g. if let Some(&foo) = ... Means you won't need to dereference foo inside the block.