error[E0261]: use of undeclared lifetime name `'a`
  --> $DIR/suggestion-for-introducing-lifetime-into-binder.rs:3:16
   |
LL |     for<> |_: &'a ()| -> () {};
   |                ^^ undeclared lifetime
   |
help: consider introducing lifetime `'a` here
   |
LL |     for<'a, > |_: &'a ()| -> () {};
   |         +++
help: consider introducing lifetime `'a` here
   |
LL | fn main<'a>() {
   |        ++++

error[E0261]: use of undeclared lifetime name `'b`
  --> $DIR/suggestion-for-introducing-lifetime-into-binder.rs:5:18
   |
LL |     for<'a> |_: &'b ()| -> () {};
   |                  ^^ undeclared lifetime
   |
help: consider introducing lifetime `'b` here
   |
LL |     for<'b, 'a> |_: &'b ()| -> () {};
   |         +++
help: consider introducing lifetime `'b` here
   |
LL | fn main<'b>() {
   |        ++++

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0261`.