According to PHPdoc.org, you can use the @see tag for this .
function count()
{
<...>
}
In addition, PHPdoc.org recommends using @see in the case of the @deprecated method :
It is RECOMMENDED (but not required) to provide an additional description indicating why the related item is out of date. If it is replaced by another method, it is RECOMMENDED to add the @see tag in the same PHPDoc pointing to the new element.