error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
  --> $DIR/issue-20831-debruijn.rs:28:33
   |
LL |     fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on the method body at 28:5...
  --> $DIR/issue-20831-debruijn.rs:28:5
   |
LL |     fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...but the lifetime must also be valid for the lifetime `'a` as defined on the impl at 26:6...
  --> $DIR/issue-20831-debruijn.rs:26:6
   |
LL | impl<'a> Publisher<'a> for MyStruct<'a> {
   |      ^^
note: ...so that the types are compatible
  --> $DIR/issue-20831-debruijn.rs:28:33
   |
LL |     fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: expected `Publisher<'_>`
              found `Publisher<'_>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0495`.