Fix --gen-compare to not generate comparators for native types.

Per the definition of --gen-compare: only generate comparators for object API
generated structs. Types annoated with native_type must define their own
comparators if `--gen-compare` is enabled.

Also enables --gen-compare for native_type_test and fixes the test by adding a
comparator for the Native::Vector3D type.

Author: cosmith-nvidia

CMakeLists.txt

@@ -537,14 +537,13 @@ if(FLATBUFFERS_BUILD_TESTS)
   add_definitions(-DFLATBUFFERS_TEST_PATH_PREFIX=${CMAKE_CURRENT_SOURCE_DIR}/)
 
   # The flattest target needs some generated files
-  SET(FLATC_OPT --cpp --gen-mutable --gen-object-api --reflect-names)
-  SET(FLATC_OPT_COMP ${FLATC_OPT};--gen-compare)
+  SET(FLATC_OPT_COMP --cpp --gen-compare --gen-mutable --gen-object-api --reflect-names)
   SET(FLATC_OPT_SCOPED_ENUMS ${FLATC_OPT_COMP};--scoped-enums)
 
   compile_schema_for_test(tests/alignment_test.fbs "${FLATC_OPT_COMP}")
   compile_schema_for_test(tests/arrays_test.fbs "${FLATC_OPT_SCOPED_ENUMS}")
   compile_schema_for_test(tests/native_inline_table_test.fbs "${FLATC_OPT_COMP}")
-  compile_schema_for_test(tests/native_type_test.fbs "${FLATC_OPT}")
+  compile_schema_for_test(tests/native_type_test.fbs "${FLATC_OPT_COMP}")
   compile_schema_for_test(tests/key_field/key_field_sample.fbs "${FLATC_OPT_COMP}")
   compile_schema_for_test(tests/64bit/test_64bit.fbs "${FLATC_OPT_COMP};--bfbs-gen-embed")
   compile_schema_for_test(tests/64bit/evolution/v1.fbs "${FLATC_OPT_COMP}")

scripts/generate_code.py

@@ -355,7 +355,7 @@ def glob(path, pattern):
 )
 
 flatc(
-    ["--cpp", "--gen-mutable", "--gen-object-api", "--reflect-names"],
+    ["--cpp", "--gen-compare", "--gen-mutable", "--gen-object-api", "--reflect-names"],
     schema="native_type_test.fbs",
 )
 

src/idl_gen_cpp.cpp

@@ -512,7 +512,8 @@ class CppGenerator : public BaseGenerator {
     // Generate forward declarations for all equal operators
     if (opts_.generate_object_based_api && opts_.gen_compare) {
       for (const auto& struct_def : parser_.structs_.vec) {
-        if (!struct_def->generated) {
+        const auto native_type = struct_def->attributes.Lookup("native_type");
+        if (!struct_def->generated && !native_type) {
           SetNameSpace(struct_def->defined_namespace);
           auto nativeName = NativeName(Name(*struct_def), struct_def, opts_);
           code_ += "bool operator==(const " + nativeName + " &lhs, const " +
@@ -2190,6 +2191,12 @@ class CppGenerator : public BaseGenerator {
 
   void GenCompareOperator(const StructDef& struct_def,
                           const std::string& accessSuffix = "") {
+    // Do not generate compare operators for native types.
+    const auto native_type = struct_def.attributes.Lookup("native_type");
+    if (native_type) {
+      return;
+    }
+
     std::string compare_op;
     for (auto it = struct_def.fields.vec.begin();
          it != struct_def.fields.vec.end(); ++it) {

tests/native_type_test.fbs

@@ -14,20 +14,11 @@ struct Vector3DAlt (native_type:"Native::Vector3D", native_type_pack_name:"Vecto
   c:float;
 }
 
-// table Matrix (native_type:"Native::Matrix") {
-table Matrix {
-  rows:int32;
-  columns:int32;
-  values:[float];
-}
-
 table ApplicationData {
   vectors:[Vector3D];
   vectors_alt:[Vector3DAlt];
   position:Vector3D;
   position_inline:Vector3D (native_inline);
-  matrix:Matrix;
-  matrices:[Matrix];
 }
 
 root_type ApplicationData;