error: calling `.extend(_.chars())`
  --> tests/ui/string_extend.rs:16:5
   |
LL |     s.extend(abc.chars());
   |     ^^^^^^^^^^^^^^^^^^^^^ help: try: `s.push_str(abc)`
   |
   = note: `-D clippy::string-extend-chars` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::string_extend_chars)]`

error: calling `.extend(_.chars())`
  --> tests/ui/string_extend.rs:20:5
   |
LL |     s.extend("abc".chars());
   |     ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `s.push_str("abc")`

error: calling `.extend(_.chars())`
  --> tests/ui/string_extend.rs:24:5
   |
LL |     s.extend(def.chars());
   |     ^^^^^^^^^^^^^^^^^^^^^ help: try: `s.push_str(&def)`

error: calling `.extend(_.chars())`
  --> tests/ui/string_extend.rs:35:5
   |
LL |     s.extend(abc[0..2].chars());
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `s.push_str(&abc[0..2])`

error: aborting due to 4 previous errors