issue-83857-ub.stderr

error[E0277]: `Foo<T, U>` cannot be sent between threads safely
  --> $DIR/issue-83857-ub.rs:18:38
   |
LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i32) {
   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Foo<T, U>` cannot be sent between threads safely
   |
   = help: the trait `Send` is not implemented for `Foo<T, U>`
   = note: required because of the requirements on the impl of `WithAssoc` for `Foo<T, U>`
help: consider introducing a `where` bound, but there might be an alternative better way to express this requirement
   |
LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i32) where Foo<T, U>: Send {
   |                                                                                +++++++++++++++++++++

error: aborting due to previous error

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