error[E0308]: intrinsic has wrong type
  --> $DIR/E0308.rs:6:16
   |
LL | fn size_of<T>() {
   |                ^ expected `usize`, found `()`
   |
   = note: expected signature `fn() -> usize`
              found signature `fn() -> ()`

error: aborting due to 1 previous error

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