error: expected token: `,`
  --> $DIR/missing-comma.rs:16:19
   |
LL |     println!("{}" a);
   |                   ^

error: no rules expected the token `b`
  --> $DIR/missing-comma.rs:18:12
   |
LL |     foo!(a b);
   |           -^
   |           |
   |           help: missing comma here

error: aborting due to 2 previous errors