error[E0119]: conflicting implementations of trait `Foo` for type `u8`:
  --> $DIR/specialization-feature-gate-overlap.rs:23:1
   |
LL | impl<T> Foo for T {
   | ----------------- first implementation here
...
LL | impl Foo for u8 { //~ ERROR E0119
   | ^^^^^^^^^^^^^^^ conflicting implementation for `u8`

error: aborting due to previous error

If you want more information on this error, try using "rustc --explain E0119"