Comment 44 for bug 1488254

OpenMandriva has successfully changed the compiler to clang (3.7.1 for now, will update to 3.8 as it is released), but decided to stick with libstdc++ to preserve binary compatibility with other Linux distributions -- users want to run non-open source stuff like steam, and that stuff doesn't get built for OSes that don't have a giant user base.

OpenMandriva could switch system libraries etc. to libc++, but even then problems would likely arise (e.g. binary-only application links to Qt and expects Qt to be linked to libstdc++ -- the only "fix" would be providing 2 different versions of all C++ libraries and even then things would likely break, with e.g. libstdc++-Qt not being able to load style plugins built for libc++-Qt and vice versa, so custom installed widget themes wouldn't work for binary-only applications).

So yes, there indeed is a use case for building the entire OS with clang but not libc++ until we get to a point where relevant closed source stuff switches to libc++ (or better yet, gets open sourced so people can link it to any STL they like).