Which gcc 5.x version did you use? Are you able to test with gcc 4.9? I tried to search gcc bugzilla, but did yet found 'zarro boogs' :-). I also don't know whether SLES 12 gcc 4.8.3 is in sync with gcc.gnu.org 's gcc 4.8.3 (released 2014-05-22). If it is in sync, I 'only' have to check all bugfixes submitted and applied to gcc 5 after that date, assuming that there is a public bug report (which is not necessarily true). I will check here internally whether we can arrange paid support for SLES.