They're not rewriting all of these tools, they're improving their tool that prexists Clang.
Now, I know that's quibbling, but this really isn't: What do you think is less work and less risk for Microsoft: throwing enough resources at MVCC to make it better, or throwing enough resources at Clang to make it so that Windows and Office compile on it without introducing regressions?
Now, I know that's quibbling, but this really isn't: What do you think is less work and less risk for Microsoft: throwing enough resources at MVCC to make it better, or throwing enough resources at Clang to make it so that Windows and Office compile on it without introducing regressions?