[display] missing "this code has no effect" diagnostic for arguments

[Gama11]

The usage here is missing the "this code has no effect" diagnostic:

class Main {
	static function main() {}

	function foo(bar:Int) {
		bar;
	}
}

Contrast this with it being a regular variable (or field) instead, where it works as expected:

[Simn]

Looks like this was fixed during the tvar refactoring.

[Gama11]

I wonder if there should be a diagnostic for the argument declaration as well (there is for regular var declarations). In theory that could be used for a Rename unused argument to _ code action.