1 error[E0391]: cycle detected when processing `Foo`
2 --> $DIR/no_inferrable_concrete_type.rs:16:1
4 LL | existential type Foo: Copy; //~ cycle detected
5 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
7 note: ...which requires processing `bar`...
8 --> $DIR/no_inferrable_concrete_type.rs:19:23
10 LL | fn bar(x: Foo) -> Foo { x }
12 = note: ...which again requires processing `Foo`, completing the cycle
14 error: aborting due to previous error
16 For more information about this error, try `rustc --explain E0391`.