error[E0369]: cannot add `&str` to `&str`
  --> $DIR/issue-47380.rs:3:35
   |
LL |     println!("🦀🦀🦀🦀🦀"); let _a = b + ", World!";
   |                                      - ^ ---------- &str
   |                                      | |
   |                                      | `+` cannot be used to concatenate two `&str` strings
   |                                      &str
   |
help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left
   |
LL |     println!("🦀🦀🦀🦀🦀"); let _a = b.to_owned() + ", World!";
   |                                      ~~~~~~~~~~~~

error: aborting due to previous error

For more information about this error, try `rustc --explain E0369`.