error[E0277]: `T` cannot be sent between threads safely --> $DIR/builtin-superkinds-typaram-not-send.rs:5:32 | LL | impl Foo for T { } | ^ `T` cannot be sent between threads safely | note: required by a bound in `Foo` --> $DIR/builtin-superkinds-typaram-not-send.rs:3:13 | LL | trait Foo : Send { } | ^^^^ required by this bound in `Foo` help: consider further restricting this bound | LL | impl Foo for T { } | +++++++++++++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.