error: expected `*` or `+` --> $DIR/macro-at-most-once-rep-2015-ques-rep-feature-flag.rs:20:10 | LL | ($(a)?) => {} //~ERROR expected `*` or `+` | ^ | = note: `?` is not a macro repetition operator error: expected `*` or `+` --> $DIR/macro-at-most-once-rep-2015-ques-rep-feature-flag.rs:24:11 | LL | ($(a),?) => {} //~ERROR expected `*` or `+` | ^ | = note: `?` is not a macro repetition operator error: aborting due to 2 previous errors