error[E0282]: type annotations needed for `Option` --> $DIR/copy-guessing.rs:20:9 | LL | let n = None; | ^ ---- type must be known at this point | help: consider giving `n` an explicit type, where the type for type parameter `T` is specified | LL | let n: Option = None; | +++++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0282`.