error[E0275]: overflow normalizing the type alias `X`
  --> $DIR/infinite-vec-type-recursion.rs:6:1
   |
LL | type X = Vec<X>;
   | ^^^^^^
   |
   = note: in case this is a recursive type alias, consider using a struct, enum, or union instead

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0275`.