Building Debian/Ubuntu packages with old gcc: CFLAG adjustment? - objective-c

Question

I need to short circuit some security features in the Debian packaging process. I explain why here, knowing that your first reactions might be "don't disable security features" and "update your program to compile with new gcc."
I have to use gcc-4.6 to compile some libraries (http://pj.freefaculty.org/Swarm) because that is the last version of gcc that provided the traditional Objective-C API. After that, gcc removed the traditional headers. Hence, "upgrade your gcc" is not acceptable because we have a very large code base using the traditional Objective-C.
In Ubuntu 17.04, gcc-4.6 is no longer available, but I've found I can install it by pulling an old version from Ubuntu "trusty". It runs fine. I can compile programs and install them the old fashioned make install way.
However, I run into a problem when building Debian packages. When I run dpkg-buildpackage -rfakeroot, as I usually do to build a package, I hit a failure because the Debian packaging system has inserted CFLAGS that are not legal in gcc-4.6. In particular, the command line includes -Wdate-time and -fstack-protector-strong, both of which are not compatible with gcc-4.6.
Here's a piece of the config.log.
configure:3878: checking whether the C compiler works
configure:3900: gcc -g -O2 -fdebug-prefix-map=/home/pauljohn/LinuxDownloads/Debian/sources/amd64/swarm-Ubuntu17.04/swarm-2.4.1=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -Wl,-Bsymbolic-functions -Wl,-z,relro conftest.c >&5
cc1: error: unrecognized command line option '-Wdate-time'
cc1: error: unrecognized command line option '-fstack-protector-strong
I've inspected the debian directory with the package and I see that those flags are not manually inserted there. From what I can tell, they come along with dpkg-buildpackage.
This library I'm trying to compile is, well, an old program. Its one on which we worked, in affiliation with the Santa Fe Institute, about 15-20 years ago. It is not reasonable to rewrite this old code to use the new Objective-C interface, so it is important to live within the restriction of gcc-4.6.
So far, the most useful suggestion I've received is to drop the Debian/Ubuntu architecture and shift to a RedHat based one, where older gcc is more easily tolerated. In fact, on RedHat 6, gcc-4.6 would be somewhat ahead of the usual, while I can still install gcc-4.6 on RedHat 7, so far as I can tell. I'd rather not exclude the Ubuntu users, however, by doing that.
Any other ideas about how to navigate this would be appreciated.

Answer 1

The relevant documentation is man 1 dpkg-buildflags
You basically have two options:
override specific build features of the dpkg buildprocess, hoping to remove the right flags
export DEB_BUILD_OPTIONS="hardening=-stackprotectorstrong reproducible=-timeless"
dpkg-buildpackage -rfakeroot
strip specific build flags from specific build variables
export DEB_CPPFLAGS_STRIP="-Wdate-time"
export DEB_CFLAGS_STRIP="-fstack-protector-string"
export DEB_CXXFLAGS_STRIP="-fstack-protector-string"
dpkg-buildpackage -rfakeroot
You can also make both ways persistent via configuration files.