While I was searching for clues about a compilation problem I have had in my source, I have come across this bug report (against Mozilla\'s JavaScript engine source) related
V12.1 of the compiler has the new behaviour by default.
If you are using an earlier version of the xlC compiler use option -qdebug=KeepUnqualifiedStaticCandidate
-qdebug=KeepUnqualifiedStaticCandidate