r269100 - [VFS] Reconstruct the VFS overlay tree for more accurate lookup

[Bruno Cardoso Lopes via cfe-commits]

> What are the platform-specifics for crash reproducing? Shouldn't it
> basically be saving some files and storing some data for reconstructing?

Feature-wise the crash reproducer for modules could "just" work for
windows, there should not be anything platform-specific, I never
tested it on windows though :-)

Darwin requires lot of custom logic to handle frameworks, and those
use recursive and normal directory iterators to scan inner frameworks;
depending on the way we write the YAML file, the VFS wouldn't be able
to correctly grab all subdirs / files, which this patch fixes. We
don't collect everything because we don't want every reproducer to
contain the whole SDK.

> We've recently been working on a `--reproduce` for LLD and we haven't needed
> any ifdefs for windows (some tests that rely on really long path names need
> to be turned off, but the feature still works).

The ifdefs are for realpath or related-to, which I mentioned
previously should be abstracted properly soon.

-- 
Bruno Cardoso Lopes
http://www.brunocardoso.cc