error[E0282]: type annotations needed for `A, Error>>` --> $DIR/issue-104649.rs:24:9 | LL | let a = A(Result::Ok(Result::Ok(()))); | ^ -------------- type must be known at this point | help: consider giving `a` an explicit type, where the type for type parameter `E` is specified | LL | let a: A, Error>> = A(Result::Ok(Result::Ok(()))); | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0282`.