As pointed out, the idiomatic way to do this is to use the try operator (`?`).

But to answer your question about copies : Rust is a move-only language, copies are actually called `.clone()`, except for a few types which are cheap enough to copy that they implement the `Copy` trait.

So in the code you quoted, the match is done on the value of `result` (notice that there is not borrowing/`&` operator). The match arm `Err(err)` moves `err` out of `result` and returns it. Obviously, the compiler will optimize away all those moves, it's as if they did not exist.