error[E0282]: type annotations needed --> $DIR/cannot-infer-closure.rs:4:9 | LL | Ok(b) | ^^ cannot infer type of the type parameter `E` declared on the enum `Result` | help: consider specifying the generic arguments | LL | Ok::<(), E>(b) | +++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0282`.