error[E0277]: `T` cannot be unpinned
  --> $DIR/issue-90164.rs:5:10
   |
LL |     copy(r, w);
   |     ---- ^ the trait `Unpin` is not implemented for `T`
   |     |
   |     required by a bound introduced by this call
   |
   = note: consider using `Box::pin`
note: required by a bound in `copy`
  --> $DIR/issue-90164.rs:1:12
   |
LL | fn copy<R: Unpin, W>(_: R, _: W) {}
   |            ^^^^^ required by this bound in `copy`
help: consider restricting type parameter `T`
   |
LL | fn f<T: std::marker::Unpin>(r: T) {
   |       ++++++++++++++++++++

error: aborting due to previous error

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