[VFS] Add back setFallthrough for downstream users

This fixes lldb's build. We can remove this in the future if we want but
for now this will be nicer to existing consumers.

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Support/VirtualFileSystem.cpp b/llvm/lib/Support/VirtualFileSystem.cpp
index 8573c3a..4915168 100644
--- a/llvm/lib/Support/VirtualFileSystem.cpp
+++ b/llvm/lib/Support/VirtualFileSystem.cpp
@@ -1363,6 +1363,14 @@ StringRef RedirectingFileSystem::getExternalContentsPrefixDir() const {
   return ExternalContentsPrefixDir;
 }
 
+void RedirectingFileSystem::setFallthrough(bool Fallthrough) {
+  if (Fallthrough) {
+    Redirection = RedirectingFileSystem::RedirectKind::Fallthrough;
+  } else {
+    Redirection = RedirectingFileSystem::RedirectKind::RedirectOnly;
+  }
+}
+
 void RedirectingFileSystem::setRedirection(
     RedirectingFileSystem::RedirectKind Kind) {
   Redirection = Kind;