Will it be consider as 'false positive'?

I already updated to CI 3.1.5 and these lines are at line number#956 (system/core/Loader.php) and eval is still in use!

sorry my mistake

I checked the develop branch not the 3.1.5

It is a false positive. it rewrite the php file to support <?= if the short_open_tag is off. In php 5.4 and above this <?= is always on