Match issue

main.rs

fn row_to_string(row: &Row) -> String {
  // Details unimportant
}

let matches: Vec<(usize, usize)> = self.core
    .rows
    .iter()
    .enumerate()
    .flat_map(|(row_index, row)| {
        row_to_string(row)
            .match_indices(query)
            .map(|(char_index, _)| (row_index, char_index))
            //.collect::<Vec<(usize, usize)>>()
    })
    .collect();