error[E0277]: `UnsafeCell>` cannot be shared between threads safely --> $DIR/typeck-unsafe-always-share.rs:19:10 | LL | fn test(s: T) {} | ---- required by this bound in `test` ... LL | test(us); | ^^ `UnsafeCell>` cannot be shared between threads safely | = help: the trait `Sync` is not implemented for `UnsafeCell>` error[E0277]: `UnsafeCell` cannot be shared between threads safely --> $DIR/typeck-unsafe-always-share.rs:23:10 | LL | fn test(s: T) {} | ---- required by this bound in `test` ... LL | test(uns); | ^^^ `UnsafeCell` cannot be shared between threads safely | = help: the trait `Sync` is not implemented for `UnsafeCell` error[E0277]: `UnsafeCell` cannot be shared between threads safely --> $DIR/typeck-unsafe-always-share.rs:27:5 | LL | fn test(s: T) {} | ---- required by this bound in `test` ... LL | test(ms); | ^^^^ `UnsafeCell` cannot be shared between threads safely | = help: within `MySync`, the trait `Sync` is not implemented for `UnsafeCell` note: required because it appears within the type `MySync` --> $DIR/typeck-unsafe-always-share.rs:8:8 | LL | struct MySync { | ^^^^^^ error[E0277]: `NoSync` cannot be shared between threads safely --> $DIR/typeck-unsafe-always-share.rs:30:10 | LL | fn test(s: T) {} | ---- required by this bound in `test` ... LL | test(NoSync); | ^^^^^^ `NoSync` cannot be shared between threads safely | = help: the trait `Sync` is not implemented for `NoSync` error: aborting due to 4 previous errors For more information about this error, try `rustc --explain E0277`.