+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+ --> $DIR/issue-87429-specialization.rs:3:12
+ |
+LL | #![feature(specialization)]
+ | ^^^^^^^^^^^^^^
+ |
+ = note: `#[warn(incomplete_features)]` on by default
+ = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+ = help: consider using `min_specialization` instead, which is more stable and complete
+
+error[E0277]: can't compare `Foo` with `Foo`
+ --> $DIR/issue-87429-specialization.rs:21:5
+ |
+LL | type Member<'a>: for<'b> PartialEq<Self::Member<'b>>;
+ | ----------------------------------- required by this bound in `Family::Member`
+...
+LL | default type Member<'a> = Foo;
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no implementation for `Foo == Foo`
+ |
+ = help: the trait `PartialEq` is not implemented for `Foo`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0277`.