| error[E0369]: binary operation `==` cannot be applied to type `Vec<Foo>` | 
 |   --> $DIR/eq-vec.rs:11:5 | 
 |    | | 
 | LL |     assert_eq!(vec1, vec2); | 
 |    |     ^^^^^^^^^^^^^^^^^^^^^^ | 
 |    |     | | 
 |    |     Vec<Foo> | 
 |    |     Vec<Foo> | 
 |    | | 
 | note: an implementation of `PartialEq` might be missing for `Foo` | 
 |   --> $DIR/eq-vec.rs:3:5 | 
 |    | | 
 | LL |     enum Foo { | 
 |    |     ^^^^^^^^ must implement `PartialEq` | 
 |    = note: this error originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info) | 
 | help: consider annotating `Foo` with `#[derive(PartialEq)]` | 
 |    | | 
 | LL +     #[derive(PartialEq)] | 
 | LL |     enum Foo { | 
 |    | | 
 |  | 
 | error: aborting due to 1 previous error | 
 |  | 
 | For more information about this error, try `rustc --explain E0369`. |