error[E0119]: conflicting implementations of trait `Foo` for type `u8`
  --> $DIR/specialization-feature-gate-overlap.rs:13:1
   |
LL | impl<T> Foo for T {
   | ----------------- first implementation here
...
LL | impl Foo for u8 {
   | ^^^^^^^^^^^^^^^ conflicting implementation for `u8`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0119`.