fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions AFAIK `[0; 3]` is basically a syntax sugar for `[0, 0, 0]` so it should return whether the repeat's element can have side effects, like what it does on arrays. And it seems that the rule for unary operators and indexings can be applied to binary operators as well.