error[E0774]: `derive` may only be applied to structs, enums and unions
  --> $DIR/issue-49934-errors.rs:1:8
   |
LL | fn foo<#[derive(Debug)] T>() {
   |        ^^^^^^^^^^^^^^^^

error[E0774]: `derive` may only be applied to structs, enums and unions
  --> $DIR/issue-49934-errors.rs:4:9
   |
LL |         #[derive(Debug)]
   |         ^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0774`.