error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates --> $DIR/issue-26262.rs:7:6 | LL | impl S { | ^ unconstrained type parameter error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates --> $DIR/issue-26262.rs:17:6 | LL | impl<'a,T: Trait2<'a>> Trait1<>::Foo> for T { | ^^ unconstrained lifetime parameter error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0207`.