error[E0282]: type annotations needed
  --> $DIR/fallback_inference.rs:4:5
   |
LL |     PhantomData
   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the struct `PhantomData`
   |
help: consider specifying the generic argument
   |
LL |     PhantomData::<T>
   |                +++++

error: aborting due to 1 previous error

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