error[E0119]: conflicting implementations of trait `MyTrait` for type `(MyType,)` --> $DIR/coherence_copy_like_err_tuple.rs:18:1 | LL | impl MyTrait for T { } | ---------------------------------- first implementation here ... LL | impl MyTrait for (MyType,) { } | ^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `(MyType,)` | = note: upstream crates may add a new impl of trait `lib::MyCopy` for type `(MyType,)` in future versions error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0119`.