Samples to test issue: https://youtrack.jetbrains.com/issue/IDEA-81911

unicode-tests.php

<?php
/**
 * Created by PhpStorm.
 * User: Ash ([email protected])
 * Date: 23-Apr-16
 * Time: 4:31 PM
 */

// வார்த்தைகள்
/* வார்த்தைகள் */
/*** வார்த்தைகள் */ # subscript kerning fails for phpDoc comments on v2016.1
/*** "வார்த்தைகள்" */ # subscript kerning works correctly in phpDocs when surrounded with double-quotes. (Issue exists for Khmer as well. Need to test other languages)
# "வார்த்தைகள்"
/* todo - வார்த்தைகள் */
$tamil ="வார்த்தைகள்";

// "ជំរាបសួរ មិត្តភ"
/* "ជំរាបសួរ មិត្តភ" */
/*** ជំរាបសួរ មិត្តភ */ #kerning bug
/*** "ជំរាបសួរ មិត្តភ" */
/* todo - "ជំរាបសួរ មិត្តភ" */
$khmer ="ជំរាបសួរ មិត្តភ";

//     
/*      */
/***      */
/* todo -      */

$klingon = "    ";