How correct overwrite %optflags direct in spec file ?
$ rpm --eval %optflags # Fedora 29
-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection
I need replace -O2 by -O in %optflags macro direct in my spec file ? I found only this one solution:
%global optflags %(echo %{optflags} | sed 's/-O[0-3]/-O/')
It is correct ?
Note rpmbuild -ba --define "optflags -O bla bla" my.spec it is not a solution for my case.
The %{optflags} macro, works as a wrapper with many other macros on it. The -O2 is an individual compiler flag which usually can be defined in CFLAGS.
When running rpm --showrc|grep '\-O2' we can see it is part of the macro _general_options.
So you can adjust it in the spec file as:
%define _general_options -O
The %{optflags} will inherit this macro and as result the -O2 will become -O
Alternatively you can use:
%define _general_option -O %{?_lto_cflags} -fexceptions -g -grecord-gcc-switches -pipe
This way, you will keep everything but just change the -O2 flag
A good reference is the buildflags documentation