vlib/v/checker/tests/invalid_insert_references_test.vv:4:12: warning: cannot add a reference to an immutable object to a mutable array
    2 | fn test_invalid_insert_references() {
    3 |     b := 0
    4 |     mut a := [&b]
      |               ^
    5 |     mut c := 1
    6 |     a << &c
vlib/v/checker/tests/invalid_insert_references_test.vv:8:7: error: cannot append `int literal` to `[]&int`
    6 |     a << &c
    7 |     c = 2
    8 |     a << 1
      |          ^
    9 |     println(a)
   10 | }