Convert local method parameter variables to instance variables

[tomphp]

I've currently noticed some funny behaviour with convert local variable to instance variable when the local variable is a method parameter. Currently if you convert myvar in the following code

class X
{
    public function doSomething($myvar)
    {
        $myvar++;

        return $myvar;
    }
}

You get something like this

class X
{
    private $myvar;

    public function doSomething($this->myvar)
    {
        $this->myvar++;

        return $this->myvar;
    }
}

Which includes syntax errors as well as logic errors. What I think it should actually produce is something like this:

class X
{
    private $myvar;

    public function doSomething($myvar)
    {
        $this->myvar = $myvar;

        $this->myvar++;

        return $this->myvar;
    }
}