http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58678
--- Comment #40 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- David, the Calligra link error from comment 36 and comment 31 are caused by ConditionCommand.cpp.o. With -flto it contains: U _ZN8Calligra6Sheets5qHashERKNS0_10ConditionsE Without -flto the undefined symbol is gone. I'm currently reducing this issue.