error[E0277]: `std::rc::Rc<u32>` cannot be sent between threads safely
  --> $DIR/trait-alias-cross-crate.rs:14:5
   |
LL |     use_alias::<Rc<u32>>();
   |     ^^^^^^^^^^^^^^^^^^^^ `std::rc::Rc<u32>` cannot be sent between threads safely
   |
   = help: the trait `std::marker::Send` is not implemented for `std::rc::Rc<u32>`
note: required by `use_alias`
  --> $DIR/trait-alias-cross-crate.rs:10:1
   |
LL | fn use_alias<T: SendSync>() {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0277]: `std::rc::Rc<u32>` cannot be shared between threads safely
  --> $DIR/trait-alias-cross-crate.rs:14:5
   |
LL |     use_alias::<Rc<u32>>();
   |     ^^^^^^^^^^^^^^^^^^^^ `std::rc::Rc<u32>` cannot be shared between threads safely
   |
   = help: the trait `std::marker::Sync` is not implemented for `std::rc::Rc<u32>`
note: required by `use_alias`
  --> $DIR/trait-alias-cross-crate.rs:10:1
   |
LL | fn use_alias<T: SendSync>() {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.