I suspect this got lost in the last migration from contint1001 to doc1001.
https://doc.wikimedia.org/mediawiki-core/master/php/search.php?query=ObjectCache
... shows no results.
Instead, the HTML output contains:
<script language="php"> require_once "search_functions.php"; main(); </script>
Note: Doxygen 1.8.13, shipped by Debian Stretch, does not support PHP 7. 1.8.15 or a cherry pick would fix it though.
Upstream bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925068