error[E0308]: mismatched types
  --> $DIR/closure-print-generic-2.rs:6:22
   |
LL |         let c = || println!("{} {}", t, x);
   |                 -- the found closure
LL |         let c1: () = c;
   |                 --   ^ expected `()`, found closure
   |                 |
   |                 expected due to this
   |
   = note: expected unit type `()`
                found closure `{closure@$DIR/closure-print-generic-2.rs:5:17: 5:19}`
help: use parentheses to call this closure
   |
LL |         let c1: () = c();
   |                       ++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.