error: invalid fragment specifier `expr_2021`
  --> $DIR/expr_2021_old_edition.rs:6:6
   |
LL |     ($e:expr_2021) => {
   |      ^^^^^^^^^^^^
   |
   = help: fragment specifier `expr_2021` requires Rust 2021 or later
           valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`

error: no rules expected the token `(`
  --> $DIR/expr_2021_old_edition.rs:12:8
   |
LL | macro_rules! m {
   | -------------- when calling this macro
...
LL |     m!(());
   |        ^ no rules expected this token in macro call
   |
note: while trying to match meta-variable `$e:ident`
  --> $DIR/expr_2021_old_edition.rs:6:6
   |
LL |     ($e:expr_2021) => {
   |      ^^^^^^^^^^^^

error: aborting due to 2 previous errors