Fix MessageDifferencer and MessagePatch to support the case where the two messages store different payload types in an Any field. Before this CL, MessageDifferencer::Compare would report false without producing any diff.

After this CL, it will compute a diff by without interpreting the payloads.

PiperOrigin-RevId: 554503691

src/google/protobuf/util/message_differencer.cc

@@ -639,13 +639,13 @@ bool MessageDifferencer::Compare(const Message& message1,
     std::unique_ptr<Message> data1;
     std::unique_ptr<Message> data2;
     if (unpack_any_field_.UnpackAny(message1, &data1) &&
-        unpack_any_field_.UnpackAny(message2, &data2)) {
-      // Avoid DFATAL for different descriptors in google.protobuf.Any payloads.
-      if (data1->GetDescriptor() != data2->GetDescriptor()) {
-        return false;
-      }
+        unpack_any_field_.UnpackAny(message2, &data2) &&
+        data1->GetDescriptor() == data2->GetDescriptor()) {
       return Compare(*data1, *data2, unpacked_any + 1, parent_fields);
     }
+    // If the Any payload is unparsable, or the payload types are different
+    // between message1 and message2, fall through and treat Any as a regular
+    // proto.
   }
 
   bool unknown_compare_result = true;

src/google/protobuf/util/message_differencer_unittest.cc

@@ -3983,6 +3983,26 @@ TEST(AnyTest, Simple) {
   EXPECT_EQ("modified: any_value.a: 20 -> 21\n", difference_string);
 }
 
+TEST(AnyTest, DifferentTypes) {
+  protobuf_unittest::TestField value1;
+  value1.set_a(20);
+  protobuf_unittest::ForeignMessage value2;
+  value2.set_c(30);
+
+  protobuf_unittest::TestAny m1, m2;
+  m1.mutable_any_value()->PackFrom(value1);
+  m2.mutable_any_value()->PackFrom(value2);
+  util::MessageDifferencer message_differencer;
+  std::string difference_string;
+  message_differencer.ReportDifferencesToString(&difference_string);
+  EXPECT_FALSE(message_differencer.Compare(m1, m2));
+  // Any should be treated as a regular proto when the payload types differ.
+  EXPECT_THAT(
+      difference_string,
+      testing::ContainsRegex(
+          R"(type_url: ".+/protobuf_unittest.TestField\" -> ".+/protobuf_unittest.ForeignMessage")"));
+}
+
 TEST(Anytest, TreatAsSet) {
   protobuf_unittest::TestField value1, value2;
   value1.set_a(20);