If you do decide to do this please only do it where needed, i.e. on i386 or 10.5 PPC. Newer systems that work fine with 7.5 should stay on that version.
Hmm. May be too complicated to do that. gcc7 installs nothing much useful on newer systems anyway. Ah well, maybe Iain will fix it. My systems are fine, after rolling back to libgcc7 7.4.x When you see tickets, just tell people to roll back for the next few months until this gets properly sorted out, if it ever does. K