--- /dev/null
+error[E0277]: the trait bound `u8: Identity` is not satisfied
+ --> $DIR/projection-as-union-type-error.rs:13:9
+ |
+LL | a: <Foo as Identity>::Identity,
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Identity` is not implemented for `u8`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.