error[E0119]: conflicting implementations of trait `Trait<_>`
  --> $DIR/opaques.rs:27:1
   |
LL | impl<T> Trait<T> for T {
   | ---------------------- first implementation here
...
LL | impl<T> Trait<T> for Alias<T> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation

error[E0282]: type annotations needed
  --> $DIR/opaques.rs:11:19
   |
LL | pub fn cast<T>(x: Container<Alias<T>, T>) -> Container<T, T> {
   |                   ^^^^^^^^^^^^^^^^^^^^^^ cannot infer type

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0119, E0282.
For more information about an error, try `rustc --explain E0119`.