vlib/v/parser/tests/postfix_err.vv:5:10: warning: `++` operator can only be used as a statement
    3 | fn test_postfix() {
    4 |     mut x := 1
    5 |     _ = (x++)
      |             ^
    6 |     x--, x-- // OK
    7 |     f(x++)
vlib/v/parser/tests/postfix_err.vv:7:7: warning: `++` operator can only be used as a statement
    5 |     _ = (x++)
    6 |     x--, x-- // OK
    7 |     f(x++)
      |          ^
    8 |     a := [x]
    9 |     _ = a[x--]
vlib/v/parser/tests/postfix_err.vv:9:11: warning: `--` operator can only be used as a statement
    7 |     f(x++)
    8 |     a := [x]
    9 |     _ = a[x--]
      |              ^
   10 | }
   11 |