error[E0308]: mismatched types
  --> $DIR/noexporttypeexe.rs:20:18
   |
LL |   let x: isize = noexporttypelib::foo();
   |                  ^^^^^^^^^^^^^^^^^^^^^^ expected isize, found enum `std::option::Option`
   |
   = note: expected type `isize`
              found type `std::option::Option<isize>`

error: aborting due to previous error

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