[llvm][vfs] For virtual directories, use the virtual path as the real path

A follow-up to D135841. This patch returns the virtual path for directories from `RedirectingFileSystem`. This ensures the contents of `Path` are the same as the contents of `FS->getRealPath(Path)`. This also means we can drop the workaround in Clang's module map canonicalization, where we couldn't use the real path for a directory if it resolved to a different `DirectoryEntry`. In addition to that, we can also avoid introducing new workaround for a bug triggered by the newly introduced test case.

Reviewed By: benlangmuir

Differential Revision: https://reviews.llvm.org/D135849

1 files changed, 2 insertions, 12 deletions

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index cf546c4..7a22fea 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -1325,18 +1325,8 @@ ModuleMap::canonicalizeModuleMapPath(SmallVectorImpl<char> &Path) {
 
   // Canonicalize the directory.
   StringRef CanonicalDir = FM.getCanonicalName(*DirEntry);
-  if (CanonicalDir != Dir) {
-    auto CanonicalDirEntry = FM.getDirectory(CanonicalDir);
-    // Only use the canonicalized path if it resolves to the same entry as the
-    // original. This is not true if there's a VFS overlay on top of a FS where
-    // the directory is a symlink. The overlay would not remap the target path
-    // of the symlink to the same directory entry in that case.
-    if (CanonicalDirEntry && *CanonicalDirEntry == *DirEntry) {
-      bool Done = llvm::sys::path::replace_path_prefix(Path, Dir, CanonicalDir);
-      (void)Done;
-      assert(Done && "Path should always start with Dir");
-    }
-  }
+  if (CanonicalDir != Dir)
+    llvm::sys::path::replace_path_prefix(Path, Dir, CanonicalDir);
 
   // In theory, the filename component should also be canonicalized if it
   // on a case-insensitive filesystem. However, the extra canonicalization is