Fix building specific Swift files in swift-clang with MSVC

lib/APINotes/APINotesYAMLCompiler.cpp

@@ -164,7 +164,7 @@ namespace {
     AvailabilityItem() : Mode(APIAvailability::Available), Msg("") {}
   };
 
-  static llvm::Optional<NullabilityKind> AbsentNullability = llvm::None;
+  static llvm::Optional<NullabilityKind> AbsentNullability {};
   static llvm::Optional<NullabilityKind> DefaultNullability =
     NullabilityKind::NonNull;
   typedef std::vector<clang::NullabilityKind> NullabilitySeq;

lib/Sema/SemaAPINotes.cpp

@@ -131,8 +131,7 @@ namespace {
          Sema &S, Decl *D, bool shouldAddAttribute,
          VersionedInfoRole role,
          llvm::function_ref<A *()> createAttr,
-         llvm::function_ref<specific_attr_iterator<A>(Decl *)> getExistingAttr =
-           [](Decl *decl) { return decl->specific_attr_begin<A>(); }) {
+         llvm::function_ref<specific_attr_iterator<A>(Decl *)> getExistingAttr) {
     switch (role) {
     case VersionedInfoRole::AugmentSource:
       // If we're not adding an attribute, there's nothing to do.
@@ -168,6 +167,17 @@ namespace {
       break;
     }
   }
+
+  template<typename A>
+  void handleAPINotedAttribute(
+         Sema &S, Decl *D, bool shouldAddAttribute,
+         VersionedInfoRole role,
+         llvm::function_ref<A *()> createAttr) {
+    handleAPINotedAttribute<A>(S, D, shouldAddAttribute, role, createAttr, 
+    [](Decl *decl) {
+        return decl->specific_attr_begin<A>();
+    });
+  }
 }
 
 static void ProcessAPINotes(Sema &S, Decl *D,

lib/Sema/SemaType.cpp

@@ -3522,7 +3522,7 @@ static void recordNullabilitySeen(Sema &S, SourceLocation loc) {
     S.Diag(fileNullability.PointerLoc, diag::warn_nullability_missing_array);
   } else {
     S.Diag(fileNullability.PointerLoc, diag::warn_nullability_missing)
-      << fileNullability.PointerKind;
+      << static_cast<unsigned>(fileNullability.PointerKind);
   }
 }