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 `a` with a similar name, but with different arguments
  --> $DIR/issue-117794.rs:4:5
   |
LL |     fn a(&self) -> impl Foo {
   |     ^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error

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