What else can we now do with the new GCC5 to improve codebase hardening

Noting the recent question: What is the most hardened set of options for GCC compiling C/C++?

Is there anything else that can be shared regarding the new version of GCC, v5 for 32/64bit targets.

I'd like to be able to feed the knowledge back into the Arch Linux community as they will soon be rebuilding all the packages dependent on the lib as per: http://ift.tt/1vGvy0W