Adding to Phabricator at Manuel's suggestion. Original thread here: http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140210/098787.html.
Summary of changes since the original patch:
- Since the symlink issue that Dmitri pointed out is going to be a bigger fix, I've pulled all the OverlayFileSystem bits out of this patch. I was hoping to start getting some testing for a half-baked overlay fs, but this issue convinced me it wasn't worth the trouble.
- Moved static status queries to be methods of Status
- Some smaller stuff from the reviews (e.g. using LLVM_OVERRIDE)