error: prefix `f` is unknown
  --> $DIR/dont-ice-on-invalid-lifetime-in-macro-definition.rs:5:17
   |
LL |             e::<f'g>
   |                 ^ unknown prefix
   |
   = note: prefixed identifiers and literals are reserved since Rust 2021
help: consider inserting whitespace here
   |
LL |             e::<f 'g>
   |                  +

error: aborting due to 1 previous error