1 files changed, 7 insertions, 3 deletions
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index bb6a450222d..0ee2b2b2215 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -4578,9 +4578,13 @@ ASTReader::ReadSubmoduleBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
         if (!CurrentModule->getUmbrellaHeader())
           ModMap.setUmbrellaHeader(CurrentModule, Umbrella);
         else if (CurrentModule->getUmbrellaHeader() != Umbrella) {
-          if ((ClientLoadCapabilities & ARR_OutOfDate) == 0)
-            Error("mismatched umbrella headers in submodule");
-          return OutOfDate;
+          // This can be a spurious difference caused by changing the VFS to
+          // point to a different copy of the file, and it is too late to
+          // to rebuild safely.
+          // FIXME: If we wrote the virtual paths instead of the 'real' paths,
+          // after input file validation only real problems would remain and we
+          // could just error. For now, assume it's okay.
+          break;
         }
       }
       break;