Redefinition of property 'x' inherited from 'y'

Sample code:

//...
class base {
    protected $size;
    
    protected function init_size($size) {
        $this->size = $size;
    }
}
class derived extends base {
    public $size;           // Redefinition of property 'size' inherited from 'base'
    //...
}
//...

You redefined property inherited from base class.