error[E0277]: `T` cannot be sent between threads safely --> $DIR/builtin-superkinds-in-metadata.rs:13:23 | LL | impl RequiresRequiresShareAndSend for X { } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `T` cannot be sent between threads safely | note: required because it appears within the type `X` --> $DIR/builtin-superkinds-in-metadata.rs:9:8 | LL | struct X(T); | ^ note: required by a bound in `RequiresRequiresShareAndSend` --> $DIR/auxiliary/trait_superkinds_in_metadata.rs:7:58 | LL | pub trait RequiresRequiresShareAndSend : RequiresShare + Send { } | ^^^^ required by this bound in `RequiresRequiresShareAndSend` help: consider further restricting this bound | LL | impl RequiresRequiresShareAndSend for X { } | +++++++++++++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.