Given the fact that there exists a working tool to switch the compiler version in Gentoo I don't see why qemu's ebuild shouldn't make use of it rather than exit with an error if the wrong compiler is used. This would be very useful for batch installations/upgrades where qemu is emerged alongside other packages. Interrupting this process for something that can be done automatically can be quite an annoying waste of persons' time. (Thankfully this isn't a case for me or else a lot of kittens would be dying right now)
No.
