error: character literal may only contain one codepoint
  --> $DIR/str-as-char.rs:4:14
   |
LL |     println!('●●');
   |              ^^^^
   |
help: if you meant to write a string literal, use double quotes
   |
LL |     println!("●●");
   |              ~  ~

error: aborting due to 1 previous error