fix build: fix userver-ydb build on certain compilers with C++20

commit_hash:333a6b927b26b33f3d8ba9bed88a24c8eb56878c

Author: Anton3

CMakeLists.txt

@@ -90,6 +90,10 @@ endif()
 set(USERVER_YDB_DEFAULT OFF)
 if(USERVER_FEATURE_CORE AND USERVER_BUILD_ALL_COMPONENTS)
     set(USERVER_YDB_DEFAULT ON)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS "13.1")
+        # ydb-cpp-sdk requires <format> header support, and GCC only implemented it in 13.1.
+        set(USERVER_YDB_DEFAULT OFF)
+    endif()
 endif()
 
 option(USERVER_CONAN "Build with Conan packages" "${CONAN_EXPORTED}")

ydb/tests/scan_table_test.cpp

@@ -14,11 +14,13 @@ UTEST_F(YdbScanTable, Simple) {
 
     auto results = GetTableClient().ExecuteScanQuery("SELECT * FROM test_table ORDER BY key");
 
-    auto cursor = results.GetNextCursor();
-    ASSERT_TRUE(cursor);
-    AssertArePreFilledRows(std::move(*cursor), {1, 2, 3});
+    {
+        auto cursor = results.GetNextCursor();
+        ASSERT_TRUE(cursor);
+        AssertArePreFilledRows(std::move(*cursor), {1, 2, 3});
+    }
 
-    while (cursor = results.GetNextCursor()) {
+    while (auto cursor = results.GetNextCursor()) {
         EXPECT_THAT(*cursor, testing::IsEmpty());
     }
 }