If there was "just one bug", that might be possible, but there are probably dozens or even hundreds of bugs fixed in newer versions of GCC which effect 4.9.x. S

If there was "just one bug", that might be possible, but there are probably dozens or even hundreds of bugs fixed in newer versions of GCC which effect 4.9.x. Someone would have to figure out which bugs are in 4.9.x, backport the patches (which could be hard if significant changes have occurred). As you say, it could in principle be done, but GCC doesn't have a huge amount of funding (most companies support LLVM/clang if they support any compiler, which to be honest makes a lot of sense, they are much more business-friendly)