Fix utf8 mode check to always return kNone for non-string fields.

This is functionally equivalent, but avoids a codegen change under editions where the inherited value of utf8_validation can change for non-string maps.

PiperOrigin-RevId: 586493296

src/google/protobuf/descriptor.cc

@@ -9576,13 +9576,18 @@ static bool IsVerifyUtf8(const FieldDescriptor* field, bool is_lite) {
 
 // Which level of UTF-8 enforcemant is placed on this file.
 Utf8CheckMode GetUtf8CheckMode(const FieldDescriptor* field, bool is_lite) {
-  if (IsStrictUtf8(field)) {
-    return Utf8CheckMode::kStrict;
-  } else if (IsVerifyUtf8(field, is_lite)) {
-    return Utf8CheckMode::kVerify;
-  } else {
-    return Utf8CheckMode::kNone;
-  }
+  if (field->type() == FieldDescriptor::TYPE_STRING ||
+      (field->is_map() && (field->message_type()->map_key()->type() ==
+                               FieldDescriptor::TYPE_STRING ||
+                           field->message_type()->map_value()->type() ==
+                               FieldDescriptor::TYPE_STRING))) {
+    if (IsStrictUtf8(field)) {
+      return Utf8CheckMode::kStrict;
+    } else if (IsVerifyUtf8(field, is_lite)) {
+      return Utf8CheckMode::kVerify;
+    }
+  }
+  return Utf8CheckMode::kNone;
 }
 
 bool IsLazilyInitializedFile(absl::string_view filename) {

src/google/protobuf/descriptor_unittest.cc

@@ -7411,8 +7411,11 @@ TEST_F(FeaturesTest, Proto2Features) {
                 [pb.cpp] { legacy_closed_enum: true })pb"));
   EXPECT_TRUE(field->has_presence());
   EXPECT_FALSE(field->requires_utf8_validation());
-  EXPECT_EQ(GetUtf8CheckMode(field, /*is_lite=*/false), Utf8CheckMode::kVerify);
-  EXPECT_EQ(GetUtf8CheckMode(field, /*is_lite=*/true), Utf8CheckMode::kNone);
+  EXPECT_EQ(
+      GetUtf8CheckMode(message->FindFieldByName("str"), /*is_lite=*/false),
+      Utf8CheckMode::kVerify);
+  EXPECT_EQ(GetUtf8CheckMode(message->FindFieldByName("str"), /*is_lite=*/true),
+            Utf8CheckMode::kNone);
   EXPECT_FALSE(field->is_packed());
   EXPECT_FALSE(field->legacy_enum_field_treated_as_closed());
   EXPECT_FALSE(HasPreservingUnknownEnumSemantics(field));
@@ -7477,8 +7480,11 @@ TEST_F(FeaturesTest, Proto3Features) {
                 [pb.cpp] { legacy_closed_enum: false })pb"));
   EXPECT_FALSE(field->has_presence());
   EXPECT_FALSE(field->requires_utf8_validation());
-  EXPECT_EQ(GetUtf8CheckMode(field, /*is_lite=*/false), Utf8CheckMode::kStrict);
-  EXPECT_EQ(GetUtf8CheckMode(field, /*is_lite=*/true), Utf8CheckMode::kStrict);
+  EXPECT_EQ(
+      GetUtf8CheckMode(message->FindFieldByName("str"), /*is_lite=*/false),
+      Utf8CheckMode::kStrict);
+  EXPECT_EQ(GetUtf8CheckMode(message->FindFieldByName("str"), /*is_lite=*/true),
+            Utf8CheckMode::kStrict);
   EXPECT_FALSE(field->is_packed());
   EXPECT_FALSE(field->legacy_enum_field_treated_as_closed());
   EXPECT_FALSE(HasPreservingUnknownEnumSemantics(field));
@@ -9214,9 +9220,9 @@ TEST_F(FeaturesTest, FieldFeatureHelpers) {
   EXPECT_FALSE(default_repeated_field->has_presence());
   EXPECT_FALSE(default_repeated_field->requires_utf8_validation());
   EXPECT_EQ(GetUtf8CheckMode(default_repeated_field, /*is_lite=*/false),
-            Utf8CheckMode::kStrict);
+            Utf8CheckMode::kNone);
   EXPECT_EQ(GetUtf8CheckMode(default_repeated_field, /*is_lite=*/true),
-            Utf8CheckMode::kStrict);
+            Utf8CheckMode::kNone);
 
   EXPECT_TRUE(required_field->has_presence());
   EXPECT_TRUE(required_field->is_required());

src/google/protobuf/generated_message_tctable_gen.cc

@@ -412,13 +412,7 @@ std::vector<TailCallTableInfo::FastFieldInfo> SplitFastFieldsForSize(
 // We only need field names for reporting UTF-8 parsing errors, so we only
 // emit them for string fields with Utf8 transform specified.
 bool NeedsFieldNameForTable(const FieldDescriptor* field, bool is_lite) {
-  if (cpp::GetUtf8CheckMode(field, is_lite) == cpp::Utf8CheckMode::kNone)
-    return false;
-  return field->type() == FieldDescriptor::TYPE_STRING ||
-         (field->is_map() && (field->message_type()->map_key()->type() ==
-                                  FieldDescriptor::TYPE_STRING ||
-                              field->message_type()->map_value()->type() ==
-                                  FieldDescriptor::TYPE_STRING));
+  return cpp::GetUtf8CheckMode(field, is_lite) != cpp::Utf8CheckMode::kNone;
 }
 
 absl::string_view FieldNameForTable(