Add missing enum case in TypeKind calculation.

Add more tests for it.

PiperOrigin-RevId: 698875053

Author: protobuf-github-bot

src/google/protobuf/map.h

@@ -412,7 +412,9 @@ class PROTOBUF_EXPORT UntypedMapBase {
     if constexpr (std::is_same_v<T, bool>) {
       return TypeKind::kBool;
     } else if constexpr (std::is_same_v<T, int32_t> ||
-                         std::is_same_v<T, uint32_t>) {
+                         std::is_same_v<T, uint32_t> || std::is_enum_v<T>) {
+      static_assert(sizeof(T) == 4,
+                    "Only enums with the right underlying type are supported.");
       return TypeKind::kU32;
     } else if constexpr (std::is_same_v<T, int64_t> ||
                          std::is_same_v<T, uint64_t>) {

src/google/protobuf/map_test.cc

@@ -298,15 +298,33 @@ void TestGetTypeInfoDynamic(void (*)(Key...), void (*)(Value...)) {
 }
 
 TEST(MapTest, StaticTypeInfoMatchesDynamicOne) {
+  enum SomeEnum : int {};
+
   TestGetTypeInfoDynamic(
+      static_cast<void (*)(bool, int32_t, uint32_t, int64_t, uint64_t,
+                           std::string)>(nullptr),
       static_cast<void (*)(bool, int32_t, uint32_t, int64_t, uint64_t, float,
-                           double, std::string)>(nullptr),
-      static_cast<void (*)(bool, int32_t, uint32_t, int64_t, uint64_t, float,
-                           double, std::string,
+                           double, std::string, SomeEnum,
                            protobuf_unittest::TestEmptyMessage,
                            protobuf_unittest::TestAllTypes)>(nullptr));
 }
 
+TEST(MapTest, StaticTypeKindWorks) {
+  enum SomeEnum : int {};
+
+  using UMB = UntypedMapBase;
+  EXPECT_EQ(UMB::TypeKind::kBool, UMB::StaticTypeKind<bool>());
+  EXPECT_EQ(UMB::TypeKind::kU32, UMB::StaticTypeKind<int32_t>());
+  EXPECT_EQ(UMB::TypeKind::kU32, UMB::StaticTypeKind<uint32_t>());
+  EXPECT_EQ(UMB::TypeKind::kU32, UMB::StaticTypeKind<SomeEnum>());
+  EXPECT_EQ(UMB::TypeKind::kU64, UMB::StaticTypeKind<int64_t>());
+  EXPECT_EQ(UMB::TypeKind::kU64, UMB::StaticTypeKind<uint64_t>());
+  EXPECT_EQ(UMB::TypeKind::kString, UMB::StaticTypeKind<std::string>());
+  EXPECT_EQ(UMB::TypeKind::kMessage,
+            UMB::StaticTypeKind<protobuf_unittest::TestAllTypes>());
+  EXPECT_EQ(UMB::TypeKind::kUnknown, UMB::StaticTypeKind<void**>());
+}
+
 TEST(MapTest, IteratorNodeFieldIsNullPtrAtEnd) {
   Map<int, int> map;
   EXPECT_EQ(internal::UntypedMapIterator::FromTyped(map.cbegin()).node_,