error: implementation of `FnOnce` is not general enough
  --> $DIR/rfc1623.rs:28:8
   |
LL |     f: &id,
   |        ^^^ implementation of `FnOnce` is not general enough
   |
   = note: `fn(&'2 Foo<'_>) -> &'2 Foo<'_> {id::<&'2 Foo<'_>>}` must implement `FnOnce<(&'1 Foo<'b>,)>`, for any lifetime `'1`...
   = note: ...but it actually implements `FnOnce<(&'2 Foo<'_>,)>`, for some specific lifetime `'2`

error: aborting due to previous error