error[E0282]: type annotations needed for `[_; 0]`
  --> $DIR/suggest-closure-return-type-2.rs:4:18
   |
LL |     unbound_drop(|| { [] })
   |                  ^^   -- type must be known at this point
   |
help: try giving this closure an explicit return type
   |
LL |     unbound_drop(|| -> [_; 0] { [] })
   |                     +++++++++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0282`.