Change `PrintFreeFieldNumbers` to not assume that groups occupy the same field range as their containing messages.

PiperOrigin-RevId: 525876198

src/google/protobuf/compiler/command_line_interface.cc

@@ -2269,10 +2269,8 @@ Parse PROTO_FILES and generate output based on the options given:
                               with a non-zero exit code if any warnings
                               are generated.
   --print_free_field_numbers  Print the free field numbers of the messages
-                              defined in the given proto files. Groups share
+                              defined in the given proto files. Extension ranges
-                              the same field number space with the parent
+                              are counted as occupied fields numbers.
-                              message. Extension ranges are counted as
-                              occupied fields numbers.
   --enable_codegen_trace      Enables tracing which parts of protoc are
                               responsible for what codegen output. Not supported
                               by all backends or on all platforms.)";
@@ -2739,13 +2737,9 @@ typedef std::pair<int, int> FieldRange;
 void GatherOccupiedFieldRanges(
     const Descriptor* descriptor, absl::btree_set<FieldRange>* ranges,
     std::vector<const Descriptor*>* nested_messages) {
-  absl::flat_hash_set<const Descriptor*> groups;
   for (int i = 0; i < descriptor->field_count(); ++i) {
     const FieldDescriptor* fd = descriptor->field(i);
     ranges->insert(FieldRange(fd->number(), fd->number() + 1));
-    if (fd->type() == FieldDescriptor::TYPE_GROUP) {
-      groups.insert(fd->message_type());
-    }
   }
   for (int i = 0; i < descriptor->extension_range_count(); ++i) {
     ranges->insert(FieldRange(descriptor->extension_range(i)->start,
@@ -2759,11 +2753,7 @@ void GatherOccupiedFieldRanges(
   // post-order strict.
   for (int i = 0; i < descriptor->nested_type_count(); ++i) {
     const Descriptor* nested_desc = descriptor->nested_type(i);
-    if (groups.find(nested_desc) != groups.end()) {
+    nested_messages->push_back(nested_desc);
-      GatherOccupiedFieldRanges(nested_desc, ranges, nested_messages);
-    } else {
-      nested_messages->push_back(nested_desc);
-    }
   }
 }
 

src/google/protobuf/compiler/command_line_interface_unittest.cc

@@ -2688,8 +2688,11 @@ TEST_F(CommandLineInterfaceTest, PrintFreeFieldNumbers) {
       "Bar                                 free: 1 3 6-7 9 11-INF\n"
       "Baz                                 free: 1 3 6-7 9 14\n"
       "Quz.Foo                             free: 1-INF\n"
+      "Quz.C                               free: 1-4 6-INF\n"
       "Quz.E.G.Foo                         free: 1-INF\n"
-      "Quz                                 free: 1 3 6-7 12-14 16-INF\n");
+      "Quz.E.G                             free: 1-INF\n"
+      "Quz.E                               free: 1-8 10-14 16-INF\n"
+      "Quz                                 free: 1 3 5-7 12-INF\n");
 #endif
 }