error: future cannot be shared between threads safely --> $DIR/issue-64130-1-sync.rs:25:13 | LL | is_sync(bar()); | ^^^^^ future returned by `bar` is not `Sync` | = help: within `impl Future`, the trait `Sync` is not implemented for `Foo` note: future is not `Sync` as this value is used across an await --> $DIR/issue-64130-1-sync.rs:18:11 | LL | let x = Foo; | - has type `Foo` which is not `Sync` LL | baz().await; | ^^^^^ await occurs here, with `x` maybe used later LL | drop(x); LL | } | - `x` is later dropped here note: required by a bound in `is_sync` --> $DIR/issue-64130-1-sync.rs:14:15 | LL | fn is_sync(t: T) { } | ^^^^ required by this bound in `is_sync` error: aborting due to previous error