error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
  --> $DIR/issue-35139.rs:19:6
   |
19 | impl<'a> MethodType for MTFn { //~ ERROR E0207
   |      ^^ unconstrained lifetime parameter

error: aborting due to previous error

If you want more information on this error, try using "rustc --explain E0207"