"no-unsed-vars" rule does not detect variable usage before declaration

[travs]

Example input:

contract Owned {
    function setOwner(address _new) onlyOwner { NewOwner(owner, _new); owner = _new; }

    address public owner = msg.sender;    // declare after use
}

Gives error:

Variable 'owner' is declared but never used

The contract compiles/executes fine, but Solium does not detect that the variable is used.

Solium does not give an error here (expected):

contract Owned {
    address public owner = msg.sender;    // declare before use
    function setOwner(address _new) onlyOwner { NewOwner(owner, _new); owner = _new; }
}

Proposal

• Update no-unused-vars to detect usage before declaration (not error), and
• add a rule like no-use-before-define, because using before defining is probably still not best practice, but is a separate problem from not defining. Another technique can be applied along with this - ignore vars that are declared public - they're obviously made for outside reading.