Fix string_transparent_hash_ut (#158)

Author: tsayukov

util/CMakeLists.txt

@@ -91,8 +91,7 @@ if (YDB_SDK_TESTS)
       generic/stack_ut.cpp
       generic/store_policy_ut.cpp
       generic/strbuf_ut.cpp
-      # See fix/util-unit-tests branch
-      # generic/string_transparent_hash_ut.cpp
+      generic/string_transparent_hash_ut.cpp
       generic/string_ut.cpp
       generic/typelist_ut.cpp
       generic/typetraits_ut.cpp
@@ -162,8 +161,7 @@ if (YDB_SDK_TESTS)
 
   add_ydb_multiple_tests(PREFIX util-random
     FILES
-      # See fix/util-unit-tests branch
-      # random/common_ops_ut.cpp
+      random/common_ops_ut.cpp
       random/easy_ut.cpp
       random/entropy_ut.cpp
       random/fast_ut.cpp
@@ -246,17 +244,15 @@ if (YDB_SDK_TESTS)
       system/cpu_id_ut.cpp
       system/daemon_ut.cpp
       system/datetime_ut.cpp
-      # See fix/util-unit-tests branch
-      # system/direct_io_ut.cpp
+      system/direct_io_ut.cpp
       system/env_ut.cpp
       system/error_ut.cpp
       system/event_ut.cpp
       system/execpath_ut.cpp
       system/filemap_ut.cpp
       system/file_ut.cpp
       system/flock_ut.cpp
-      # See fix/util-unit-tests branch
-      # system/fstat_ut.cpp
+      system/fstat_ut.cpp
       system/fs_ut.cpp
       system/getpid_ut.cpp
       system/guard_ut.cpp
@@ -281,8 +277,7 @@ if (YDB_SDK_TESTS)
       system/src_root_ut.cpp
       system/tempfile_ut.cpp
       system/tls_ut.cpp
-      # See fix/util-unit-tests branch
-      # system/type_name_ut.cpp
+      system/type_name_ut.cpp
       system/types_ut.cpp
       # TODO: add library/cpp/testing/benchmark
       #       depends only on NBench::Clobber, that's a memory optimization barrier

util/generic/string_transparent_hash_ut.cpp

@@ -3,15 +3,28 @@
 #include "strbuf.h"
 
 #include <library/cpp/testing/unittest/registar.h>
-#include <library/cpp/containers/absl_flat_hash/flat_hash_set.h>
+
+#if __cplusplus < 202002L
+    #include <library/cpp/containers/absl_flat_hash/flat_hash_set.h>
+#else
+    #include <unordered_set>
+#endif
 
 #include <util/str_stl.h>
 
 Y_UNIT_TEST_SUITE(StringHashFunctorTests) {
     Y_UNIT_TEST(TestTransparencyWithUnorderedSet) {
         // Using Abseil hash set because `std::unordered_set` is transparent only from C++20 (while
         // we stuck with C++17 right now).
-        absl::flat_hash_set<TString, THash<TString>, TEqualTo<TString>> s = {"foo"};
+        using TTransparentHashSet =
+    #if __cplusplus < 202002L
+            absl::flat_hash_set
+    #else
+            std::unordered_set
+    #endif
+            <TString, THash<TString>, TEqualTo<TString>>;
+
+        TTransparentHashSet s = {"foo"};
         // If either `THash` or `TEqualTo` is not transparent compilation will fail.
         UNIT_ASSERT_UNEQUAL(s.find(TStringBuf("foo")), s.end());
         UNIT_ASSERT_EQUAL(s.find(TStringBuf("bar")), s.end());