diff --git a/llvm/lib/Support/YAMLTraits.cpp b/llvm/lib/Support/YAMLTraits.cpp
--- a/llvm/lib/Support/YAMLTraits.cpp
+++ b/llvm/lib/Support/YAMLTraits.cpp
@@ -527,8 +527,9 @@
 }
 
 bool Output::preflightKey(const char *Key, bool Required, bool SameAsDefault,
-                          bool &UseDefault, void *&) {
+                          bool &UseDefault, void *&SaveInfo) {
   UseDefault = false;
+  SaveInfo = nullptr;
   if (Required || !SameAsDefault || WriteDefaultValues) {
     auto State = StateStack.back();
     if (State == inFlowMapFirstKey || State == inFlowMapOtherKey) {
@@ -599,7 +600,8 @@
   StateStack.pop_back();
 }
 
-bool Output::preflightElement(unsigned, void *&) {
+bool Output::preflightElement(unsigned, void *&SaveInfo) {
+  SaveInfo = nullptr;
   return true;
 }