php 7 bug in substr_replace function

Hi everybody, I don't know if this is the right place to report bugs. please let me know for the next time. This is a small snippet that shows the wrong behaviour : <?php $line = str_repeat(' ',20); $value ='03'; $pos=0; $len='2'; $line = substr_replace($line,$value,$pos,$len); echo "[$line]\n"; ?> When running it under php 7, $line is unchanged and a message is emitted : PHP Warning: substr_replace(): 'from' and 'len' should be of same type - numerical or array in test.php on line 3. $len is not auto-casted in integer.. Btw the message is not very clear as it mentions from and len that are not within the doc. (in my real source code, $len was extracted as string from a database). When $len is an integer, the function works as expected. Tested ok on php 5.3.10 Tested Not ok on php 7.0.3 Best regards, Pascal KISSIAN