1 files changed, 4 insertions, 0 deletions
diff --git a/include/clang/Basic/VirtualFileSystem.h b/include/clang/Basic/VirtualFileSystem.h
index cc13d72a5b..9b95158987 100644
--- a/include/clang/Basic/VirtualFileSystem.h
+++ b/include/clang/Basic/VirtualFileSystem.h
@@ -325,6 +325,7 @@ class YAMLVFSWriter {
   std::vector<YAMLVFSEntry> Mappings;
   Optional<bool> IsCaseSensitive;
   Optional<bool> IsOverlayRelative;
+  Optional<bool> UseExternalNames;
   std::string OverlayDir;
 
 public:
@@ -333,6 +334,9 @@ public:
   void setCaseSensitivity(bool CaseSensitive) {
     IsCaseSensitive = CaseSensitive;
   }
+  void setUseExternalNames(bool UseExtNames) {
+    UseExternalNames = UseExtNames;
+  }
   void setOverlayDir(StringRef OverlayDirectory) {
     IsOverlayRelative = true;
     OverlayDir.assign(OverlayDirectory.str());