http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53493
--- Comment #3 from jwatte at gmail dot com 2012-05-26 19:25:50 UTC --- Created attachment 27504 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27504 The preprocessed source Generated with: avr-gcc -Os -mmcu=atmega328p -c foo.cpp -o foo.E -E Note that the "-Os" flag does not change the pre-processed source at all -- the preprocessed output is the same with or without it.