change compilation optimization flags?

Hi all

I am compiling my project under Mac, after adding in the .Pro file
CONFIG(release, debug|release):QMAKE_CXXFLAGS += -O3 -fomit-frame-pointer
however, i always see that the command where g++ is ran, includes -Os. i would like to remove it.

i tried several approaches, like
CONFIG(release, debug|release):QMAKE_CFLAGS_RELEASE -= -Os
CONFIG(release, debug|release):QMAKE_CXXFLAGS -= -Os

and
CONFIG(release, debug|release):QMAKE_CXXFLAGS = -O3 -fomit-frame-pointer
CONFIG(release, debug|release):QMAKE_CFLAGS_RELEASE = -O3 -fomit-frame-pointer
(no +)

but nothing - Os ALWAYS appear.

how do I change this?

i found the qmake.conf file, which includes a mac-g++.conf file, but i cannot change it, and chmod doesnt work: chmod: mac-g++.conf: Operation not permitted

any ideas?

thanks very much
Lior :eek: