Index: lib/Format/UnwrappedLineParser.cpp
===================================================================
--- lib/Format/UnwrappedLineParser.cpp
+++ lib/Format/UnwrappedLineParser.cpp
@@ -428,8 +428,9 @@
     parseParens();
 
   addUnwrappedLine();
-  size_t OpeningLineIndex =
-      Lines.empty() ? (UnwrappedLine::kInvalidIndex) : (Lines.size() - 1);
+  size_t OpeningLineIndex = CurrentLines->empty()
+                                ? (UnwrappedLine::kInvalidIndex)
+                                : (CurrentLines->size() - 1);
 
   ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                           MustBeDeclaration);