error[E0599]: no method named `b` found for reference `&Self` in the current scope
  --> $DIR/issue-117794.rs:5:14
   |
LL |         self.b(|| 0)
   |              ^ help: there is a method with a similar name: `a`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0599`.