http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59396
--- Comment #8 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- (In reply to Martin Nowak from comment #5) > (In reply to Georg-Johann Lay from comment #4) > > As the patch above has not been approved, it's unlikely this will ever get > > fixed... > > This should have a high priority, it makes LTO completely unusable on AVR. avr itself is an architecture that hat not a high priority in the GCC project, thus all avr issues are P4 or P5. And this is just a warning that occurs during the LTO run. Try to add -w to the lto1 run, i.e. to your link step.
