error[E0119]: conflicting implementations of trait `MyTrait` for type `(_, _)`
  --> $DIR/coherence-tuple-conflict.rs:15:1
   |
LL | impl<T> MyTrait for (T,T) {
   | ------------------------- first implementation here
...
LL | impl<A,B> MyTrait for (A,B) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `(_, _)`

error: aborting due to 1 previous error

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