Update MessageDifferencer to collect the name of no presence fields that were forced into the compare list and which have caused the comparison to fail.

PiperOrigin-RevId: 531606719

src/google/protobuf/util/message_differencer.cc

@@ -553,6 +553,8 @@ bool MessageDifferencer::FieldBefore(const FieldDescriptor* field1,
 bool MessageDifferencer::Compare(const Message& message1,
                                  const Message& message2) {
   std::vector<SpecificField> parent_fields;
+  force_compare_no_presence_fields_.clear();
+  force_compare_failure_triggering_fields_.clear();
 
   bool result = false;
   // Setup the internal reporter if need be.
@@ -580,6 +582,8 @@ bool MessageDifferencer::CompareWithFields(
   }
 
   std::vector<SpecificField> parent_fields;
+  force_compare_no_presence_fields_.clear();
+  force_compare_failure_triggering_fields_.clear();
 
   bool result = false;
 
@@ -757,12 +761,12 @@ FieldDescriptorArray MessageDifferencer::CombineFields(
 
     if (FieldBefore(field1, field2)) {
       if (fields1_scope == FULL) {
-        tmp_message_fields_.push_back(fields1[index1]);
+        tmp_message_fields_.push_back(field1);
       }
       ++index1;
     } else if (FieldBefore(field2, field1)) {
       if (fields2_scope == FULL) {
-        tmp_message_fields_.push_back(fields2[index2]);
+        tmp_message_fields_.push_back(field2);
       } else if (fields2_scope == PARTIAL && force_compare_no_presence_ &&
                  !field2->has_presence() && !field2->is_repeated()) {
         // In order to make MessageDifferencer play nicely with no-presence
@@ -772,12 +776,12 @@ FieldDescriptorArray MessageDifferencer::CombineFields(
         // Those fields will appear in fields2 (since they have non default
         // value) but will not appear in fields1 (since they have the default
         // value or were never set).
-        force_compare_no_presence_fields_.insert(fields2[index2]);
+        force_compare_no_presence_fields_.insert(field2);
-        tmp_message_fields_.push_back(fields2[index2]);
+        tmp_message_fields_.push_back(field2);
       }
       ++index2;
     } else {
-      tmp_message_fields_.push_back(fields1[index1]);
+      tmp_message_fields_.push_back(field1);
       ++index1;
       ++index2;
     }
@@ -865,6 +869,10 @@ bool MessageDifferencer::CompareWithFieldsInternal(
       ++field_index1;
       continue;
     } else if (FieldBefore(field2, field1)) {
+      if (force_compare_no_presence_fields_.contains(field2)) {
+        force_compare_failure_triggering_fields_.insert(field2->full_name());
+      }
+
       // Field 2 is not in the field list for message 1.
       if (IsIgnored(message1, message2, field2, *parent_fields)) {
         // We are ignoring field2. Report the ignore and move on to
@@ -956,6 +964,10 @@ bool MessageDifferencer::CompareWithFieldsInternal(
       fieldDifferent = !CompareFieldValueUsingParentFields(
           message1, message2, unpacked_any, field1, -1, -1, parent_fields);
 
+      if (force_compare_no_presence_fields_.contains(field1)) {
+        force_compare_failure_triggering_fields_.insert(field1->full_name());
+      }
+
       if (reporter_ != nullptr) {
         SpecificField specific_field;
         specific_field.message1 = &message1;

src/google/protobuf/util/message_differencer.h

@@ -655,6 +655,13 @@ class PROTOBUF_EXPORT MessageDifferencer {
   // differences to any previously set reporters or output strings.
   void ReportDifferencesTo(Reporter* reporter);
 
+  // Returns the list of fields which was automatically added to the list of
+  // compared fields by calling set_force_compare_no_presence and caused the
+  // last call to Compare to fail.
+  const absl::flat_hash_set<std::string>& NoPresenceFieldsCausingFailure() {
+    return force_compare_failure_triggering_fields_;
+  }
+
  private:
   // Class for processing Any deserialization.  This logic is used by both the
   // MessageDifferencer and StreamReporter classes.
@@ -947,6 +954,7 @@ class PROTOBUF_EXPORT MessageDifferencer {
   MessageFieldComparison message_field_comparison_;
   Scope scope_;
   absl::flat_hash_set<const FieldDescriptor*> force_compare_no_presence_fields_;
+  absl::flat_hash_set<std::string> force_compare_failure_triggering_fields_;
   RepeatedFieldComparison repeated_field_comparison_;
 
   absl::flat_hash_map<const FieldDescriptor*, RepeatedFieldComparison>

src/google/protobuf/util/message_differencer_unittest.cc

@@ -258,11 +258,18 @@ TEST(MessageDifferencerTest,
   // Clearing a no presence field inside a repeated field in a nested message.
   msg1.mutable_no_presence_repeated_nested(0)->clear_no_presence_bool();
   EXPECT_FALSE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_THAT(force_compare_differencer.NoPresenceFieldsCausingFailure(),
+              testing::UnorderedElementsAre(
+                  "proto3_unittest.TestNoPresenceField.no_presence_bool"));
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
+  EXPECT_TRUE(default_differencer.NoPresenceFieldsCausingFailure().empty());
   force_compare_differencer.ReportDifferencesTo(nullptr);
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(default_differencer.NoPresenceFieldsCausingFailure().empty());
 }
 
 TEST(MessageDifferencerTest,
@@ -284,7 +291,10 @@ TEST(MessageDifferencerTest,
 
   msg1.clear_no_presence_repeated_nested();
   EXPECT_TRUE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
+  EXPECT_TRUE(default_differencer.NoPresenceFieldsCausingFailure().empty());
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
@@ -308,9 +318,14 @@ TEST(MessageDifferencerTest,
 
   msg1.mutable_no_presence_nested()->clear_no_presence_bool();
   EXPECT_FALSE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_THAT(force_compare_differencer.NoPresenceFieldsCausingFailure(),
+              testing::UnorderedElementsAre(
+                  "proto3_unittest.TestNoPresenceField.no_presence_bool"));
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
 }
 
@@ -332,18 +347,27 @@ TEST(MessageDifferencerTest,
 
   msg1.clear_no_presence_nested();
   EXPECT_TRUE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
 
   // Creating an instance of the nested field will cause the comparison to fail
   // since it contains a no presence singualr field.
   msg1.mutable_no_presence_nested();
   EXPECT_FALSE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_THAT(force_compare_differencer.NoPresenceFieldsCausingFailure(),
+              testing::UnorderedElementsAre(
+                  "proto3_unittest.TestNoPresenceField.no_presence_bool"));
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
 }
 
@@ -365,9 +389,13 @@ TEST(MessageDifferencerTest,
 
   msg1.clear_no_presence_bool();
   EXPECT_FALSE(force_compare_differencer.Compare(msg1, msg2));
+  EXPECT_TRUE(
+      !force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_TRUE(default_differencer.Compare(msg1, msg2));
 
   EXPECT_FALSE(force_compare_differencer.Compare(msg2, msg1));
+  EXPECT_TRUE(
+      force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   EXPECT_FALSE(default_differencer.Compare(msg2, msg1));
 }
 
@@ -392,6 +420,8 @@ TEST(MessageDifferencerTest,
 
     msg1.mutable_no_presence_repeated_nested(0)->clear_no_presence_bool();
     EXPECT_FALSE(force_compare_differencer.Compare(msg1, msg2));
+    EXPECT_TRUE(
+        !force_compare_differencer.NoPresenceFieldsCausingFailure().empty());
   }
   EXPECT_EQ(output,
             "added: no_presence_repeated_nested[0].no_presence_bool (added for "