error[E0401]: can't use generic parameters from outer item
  --> $DIR/nested-ty-params.rs:3:16
   |
LL | fn hd<U>(v: Vec<U> ) -> U {
   |       - type parameter from outer item
LL |     fn hd1(w: [U]) -> U { return w[0]; }
   |           -    ^ use of generic parameter from outer item
   |           |
   |           help: try introducing a local generic parameter here: `<U>`

error[E0401]: can't use generic parameters from outer item
  --> $DIR/nested-ty-params.rs:3:23
   |
LL | fn hd<U>(v: Vec<U> ) -> U {
   |       - type parameter from outer item
LL |     fn hd1(w: [U]) -> U { return w[0]; }
   |           -           ^ use of generic parameter from outer item
   |           |
   |           help: try introducing a local generic parameter here: `<U>`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0401`.