fix ExportTypeToProto for empty tuple type

2 files changed, 27 insertions, 1 deletions

diff --git a/ydb/library/mkql_proto/mkql_proto.cpp b/ydb/library/mkql_proto/mkql_proto.cpp
index c09b539a746..6b9bb4b7d82 100644
--- a/ydb/library/mkql_proto/mkql_proto.cpp
+++ b/ydb/library/mkql_proto/mkql_proto.cpp
@@ -300,8 +300,9 @@ void ExportTypeToProtoImpl(TType* type, Ydb::Type& res) {
 
         case TType::EKind::Tuple: {
             auto tupleType = static_cast<TTupleType*>(type);
+            auto resTuple = res.mutable_tuple_type();
             for (ui32 index = 0; index < tupleType->GetElementsCount(); ++index) {
-                ExportTypeToProtoImpl(tupleType->GetElementType(index), *res.mutable_tuple_type()->add_elements());
+                ExportTypeToProtoImpl(tupleType->GetElementType(index), *resTuple->add_elements());
             }
 
             break;
diff --git a/ydb/library/mkql_proto/mkql_proto_ut.cpp b/ydb/library/mkql_proto/mkql_proto_ut.cpp
index 5cabfe8bcf2..1b8578780be 100644
--- a/ydb/library/mkql_proto/mkql_proto_ut.cpp
+++ b/ydb/library/mkql_proto/mkql_proto_ut.cpp
@@ -183,6 +183,23 @@ Y_UNIT_TEST_SUITE(TMiniKQLProtoTest) {
         "}\n");
     }
 
+    Y_UNIT_TEST(TestExportEmptyTupleType) {
+        TestExportType<NKikimrMiniKQL::TType>([](TProgramBuilder& pgmBuilder) {
+            TVector<TRuntimeNode> items;
+            auto pgmReturn = pgmBuilder.NewTuple(items);
+            return pgmReturn;
+        },
+        "Kind: Tuple\n");
+
+        TestExportType<Ydb::Type>([](TProgramBuilder& pgmBuilder) {
+            TVector<TRuntimeNode> items;
+            auto pgmReturn = pgmBuilder.NewTuple(items);
+            return pgmReturn;
+        },
+        "tuple_type {\n"
+        "}\n");
+    }
+    
     Y_UNIT_TEST(TestExportStructType) {
         TestExportType<NKikimrMiniKQL::TType>([](TProgramBuilder& pgmBuilder) {
             std::vector<std::pair<std::string_view, TRuntimeNode>> items;
@@ -221,6 +238,14 @@ Y_UNIT_TEST_SUITE(TMiniKQLProtoTest) {
             return pgmReturn;
         },
         "Kind: Struct\n");
+
+        TestExportType<Ydb::Type>([](TProgramBuilder& pgmBuilder) {
+            std::vector<std::pair<std::string_view, TRuntimeNode>> items;
+            auto pgmReturn = pgmBuilder.NewStruct(items);
+            return pgmReturn;
+        },
+        "struct_type {\n"
+        "}\n");
     }
 
     Y_UNIT_TEST(TestExportDictType) {