| error[E0321]: cross-crate traits with a default impl, like `std::marker::Send`, can only be implemented for a struct/enum type, not `&'static main::Foo` | |
| --> $DIR/empty_span.rs:7:5 | |
| | | |
| LL | unsafe impl Send for &'static Foo { } | |
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0321`. |