error: calling `.extend(_.chars())`
  --> $DIR/string_extend.rs:18:5
   |
LL |     s.extend(abc.chars());
   |     ^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str(abc)`
   |
   = note: `-D clippy::string-extend-chars` implied by `-D warnings`

error: calling `.extend(_.chars())`
  --> $DIR/string_extend.rs:21:5
   |
LL |     s.extend("abc".chars());
   |     ^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.push_str("abc")`

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

error: aborting due to 3 previous errors