error: use of `extend` instead of `append` for adding the full range of a second vector
  --> $DIR/append_instead_of_extend.rs:9:5
   |
LL |     vec2.extend(vec1.drain(..));
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `vec2.append(&mut vec1)`
   |
   = note: `-D clippy::append-instead-of-extend` implied by `-D warnings`

error: use of `extend` instead of `append` for adding the full range of a second vector
  --> $DIR/append_instead_of_extend.rs:14:5
   |
LL |     vec4.extend(vec3.drain(..));
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `vec4.append(&mut vec3)`

error: use of `extend` instead of `append` for adding the full range of a second vector
  --> $DIR/append_instead_of_extend.rs:18:5
   |
LL |     vec11.extend(return_vector().drain(..));
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `vec11.append(&mut return_vector())`

error: aborting due to 3 previous errors