Fix a compile error caught by bb-chapuni.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@186555 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 58bd163..ac62636 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -76,8 +76,9 @@
     DI->EmitLocation(Builder, SavedLoc);
     DI->CurLoc = SourceLocation();
     // Construct a location that has a valid scope, but no line info.
-    llvm::MDNode *Scope = DI->LexicalBlockStack.empty() ?
-      DI->TheCU() : DI->LexicalBlockStack.back();
+    llvm::DIDescriptor Scope = DI->LexicalBlockStack.empty() ?
+      llvm::DIDescriptor(DI->TheCU) :
+      llvm::DIDescriptor(DI->LexicalBlockStack.back());
     Builder.SetCurrentDebugLocation(llvm::DebugLoc::get(0, 0, Scope));
   }
 }