error[E0119]: conflicting implementations of trait `Foo` for type `u8`:
  --> $DIR/specialization-feature-gate-overlap.rs:23:1
   |
19 | / impl<T> Foo for T {
20 | |     fn foo(&self) {}
21 | | }
   | |_- first implementation here
22 | 
23 | / impl Foo for u8 { //~ ERROR E0119
24 | |     fn foo(&self) {}
25 | | }
   | |_^ conflicting implementation for `u8`

error: aborting due to previous error