[PATCH] D122549: [VFS] RedirectingFileSystem only replace path if not already mapped

[Ben Barham via Phabricator via cfe-commits]

bnbarham added inline comments.


================
Comment at: clang/lib/Basic/FileManager.cpp:273
 
-  if (Status.getName() == Filename) {
+  if (!Status.IsVFSMapped) {
     // The name matches. Set the FileEntry.
----------------
bnbarham wrote:
> dexonsmith wrote:
> > An incremental patch you could try would be:
> > ```
> > lang=c++
> > if (Status.getName() == Filename || !Status.IsVFSMapped)
> > ```
> > ... dropping all the other changes.
> > 
> > This limits the redirection hack to only apply when a RedirectingFS is involved (leaving until later the fine-tuning of when `IsVFSMapped` gets set). If this smaller change still causes a test failure, it might be easier to reason about why / how to fix it / be sure that the fix is sound.
> > 
> > Eventually we might want something like:
> > ```
> > lang=c++
> > if (!Status.IsVFSMapped) {
> >   assert(Status.getName() == Filename);
> > ```
> > I imagine that's not going to succeed yet due to the CWD behaviour in the VFSes, but as a speculative patch it might help track down whatever the problem is.
> That assertion currently won't succeed for any relative path, since `getStatValue` does the absolute pathing for relative paths. So `Status.getName()` is guaranteed to be different to `Filename` in that case.
> 
> Possibly even more odd is that the failing test passes locally on MacOSX. I'll try the suggestion above and see if they fail again.
Actually, thinking about this a bit more - the failing test doesn't use an overlay at all, so changing to the above wouldn't help at all.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D122549/new/

https://reviews.llvm.org/D122549