error[E0308]: mismatched types
  --> $DIR/wrong-ret-type.rs:12:49
   |
LL | fn mk_int() -> usize { let i: isize = 3; return i; }
   |                                                 ^ expected usize, found isize

error: aborting due to previous error

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