1 files changed, 18 insertions, 11 deletions

diff --git a/src/google/protobuf/util/field_mask_util.cc b/src/google/protobuf/util/field_mask_util.cc
index 4d0d3a46..a2e2a388 100644
--- a/src/google/protobuf/util/field_mask_util.cc
+++ b/src/google/protobuf/util/field_mask_util.cc
@@ -31,6 +31,7 @@
 #include <google/protobuf/util/field_mask_util.h>
 
 #include <google/protobuf/stubs/strutil.h>
+
 #include <google/protobuf/stubs/map_util.h>
 
 namespace google {
@@ -131,27 +132,27 @@ bool FieldMaskUtil::FromJsonString(StringPiece str, FieldMask* out) {
 bool FieldMaskUtil::GetFieldDescriptors(
     const Descriptor* descriptor, StringPiece path,
     std::vector<const FieldDescriptor*>* field_descriptors) {
-  if (field_descriptors != NULL) {
+  if (field_descriptors != nullptr) {
     field_descriptors->clear();
   }
   std::vector<string> parts = Split(path, ".");
   for (int i = 0; i < parts.size(); ++i) {
     const string& field_name = parts[i];
-    if (descriptor == NULL) {
+    if (descriptor == nullptr) {
       return false;
     }
     const FieldDescriptor* field = descriptor->FindFieldByName(field_name);
-    if (field == NULL) {
+    if (field == nullptr) {
       return false;
     }
-    if (field_descriptors != NULL) {
+    if (field_descriptors != nullptr) {
       field_descriptors->push_back(field);
     }
     if (!field->is_repeated() &&
         field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       descriptor = field->message_type();
     } else {
-      descriptor = NULL;
+      descriptor = nullptr;
     }
   }
   return true;
@@ -342,6 +343,12 @@ void FieldMaskTree::AddPath(const string& path) {
 
 void FieldMaskTree::RemovePath(const string& path,
                                const Descriptor* descriptor) {
+  if (root_.children.empty()) {
+    // Nothing to be removed from an empty tree. We shortcut it here so an empty
+    // tree won't be interpreted as a field mask containing all fields by the
+    // code below.
+    return;
+  }
   std::vector<string> parts = Split(path, ".");
   if (parts.empty()) {
     return;
@@ -349,16 +356,16 @@ void FieldMaskTree::RemovePath(const string& path,
   std::vector<Node*> nodes(parts.size());
   Node* node = &root_;
   const Descriptor* current_descriptor = descriptor;
-  Node* new_branch_node = NULL;
+  Node* new_branch_node = nullptr;
   for (int i = 0; i < parts.size(); ++i) {
     nodes[i] = node;
     const FieldDescriptor* field_descriptor =
         current_descriptor->FindFieldByName(parts[i]);
-    if (field_descriptor == NULL ||
+    if (field_descriptor == nullptr ||
         (field_descriptor->cpp_type() != FieldDescriptor::CPPTYPE_MESSAGE &&
          i != parts.size() - 1)) {
       // Invalid path.
-      if (new_branch_node != NULL) {
+      if (new_branch_node != nullptr) {
         // If add any new nodes, cleanup.
         new_branch_node->ClearChildren();
       }
@@ -366,7 +373,7 @@ void FieldMaskTree::RemovePath(const string& path,
     }
 
     if (node->children.empty()) {
-      if (new_branch_node == NULL) {
+      if (new_branch_node == nullptr) {
         new_branch_node = node;
       }
       for (int i = 0; i < current_descriptor->field_count(); ++i) {
@@ -374,7 +381,7 @@ void FieldMaskTree::RemovePath(const string& path,
       }
     }
     if (ContainsKey(node->children, parts[i])) {
-      node = node->children.at(parts[i]);
+      node = node->children[parts[i]];
       if (field_descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
         current_descriptor = field_descriptor->message_type();
       }
@@ -542,7 +549,7 @@ void FieldMaskTree::AddRequiredFieldPath(
     if (field->is_required()) {
       const string& node_name = field->name();
       Node*& child = node->children[node_name];
-      if (child == NULL) {
+      if (child == nullptr) {
         // Add required field path to the tree
         child = new Node();
       } else if (child->children.empty()){