1 error[E0119]: conflicting implementations of trait `Foo` for type `&_`
2 --> $DIR/feature-gate-with_negative_coherence.rs:5:1
4 LL | impl<T: std::ops::DerefMut> Foo for T { }
5 | ------------------------------------- first implementation here
7 LL | impl<T> Foo for &T { }
8 | ^^^^^^^^^^^^^^^^^^ conflicting implementation for `&_`
10 error: aborting due to previous error
12 For more information about this error, try `rustc --explain E0119`.