Improve support for DontSerializeDefault; Add DontSerializeDefault to fix snapshot divergence when rolling 23.2

964925e3330bb2bc336b4c2721370bbd33f05f34

1 files changed, 51 insertions, 13 deletions

diff --git a/yt/yt/core/ytree/yson_struct_detail-inl.h b/yt/yt/core/ytree/yson_struct_detail-inl.h
index c34a934c162..fefe704afb6 100644
--- a/yt/yt/core/ytree/yson_struct_detail-inl.h
+++ b/yt/yt/core/ytree/yson_struct_detail-inl.h
@@ -18,20 +18,58 @@ namespace NYT::NYTree {
 
 namespace NPrivate {
 
-// TODO(shakurov): get rid of this once concept support makes it into the standard
-// library implementation. Use equality-comparability instead.
+////////////////////////////////////////////////////////////////////////////////
+
+namespace NDetail {
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <class T>
+concept CTupleLike = requires {
+    std::tuple_size<T>{};
+};
+
+template <class T>
+concept CContainerLike = requires {
+    typename T::value_type;
+};
+
+template <class T>
+struct TEqualityComparableHelper
+{
+    constexpr static bool Value = std::equality_comparable<T>;
+};
+
+template <class T, size_t... I>
+constexpr bool IsSequenceEqualityComparable(std::index_sequence<I...> /*sequence*/)
+{
+    return (TEqualityComparableHelper<typename std::tuple_element<I, T>::type>::Value && ...);
+}
+
+template <CTupleLike T>
+struct TEqualityComparableHelper<T>
+{
+    constexpr static bool Value = IsSequenceEqualityComparable<T>(std::make_index_sequence<std::tuple_size<T>::value>());
+};
+
+template <CContainerLike T>
+struct TEqualityComparableHelper<T>
+{
+    constexpr static bool Value = TEqualityComparableHelper<typename T::value_type>::Value;
+};
+
+} // namespace NDetail
+
+////////////////////////////////////////////////////////////////////////////////
+
+// TODO(h0pless): Get rid of this once containers will have constraints for equality operator.
+// Once this will be the case, it should be safe to use std::equality_comparable here instead.
 template <class T>
-concept SupportsDontSerializeDefaultImpl =
-    std::is_arithmetic_v<T> ||
-    std::is_same_v<T, TString> ||
-    std::is_same_v<T, TDuration> ||
-    std::is_same_v<T, TGuid> ||
-    std::is_same_v<T, std::optional<std::vector<TString>>> ||
-    std::is_same_v<T, THashSet<TString>>;
+concept CRecursivelyEqualityComparable = NDetail::TEqualityComparableHelper<T>::Value;
 
 template <class T>
-concept SupportsDontSerializeDefault =
-    SupportsDontSerializeDefaultImpl<typename TWrapperTraits<T>::TRecursiveUnwrapped>;
+concept CSupportsDontSerializeDefault =
+    CRecursivelyEqualityComparable<typename TWrapperTraits<T>::TRecursiveUnwrapped>;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -654,7 +692,7 @@ template <class TValue>
 bool TYsonStructParameter<TValue>::CanOmitValue(const TYsonStructBase* self) const
 {
     const auto& value = FieldAccessor_->GetValue(self);
-    if constexpr (NPrivate::SupportsDontSerializeDefault<TValue>) {
+    if constexpr (NPrivate::CSupportsDontSerializeDefault<TValue>) {
         if (!SerializeDefault_ && value == (*DefaultCtor_)()) {
             return true;
         }
@@ -745,7 +783,7 @@ TYsonStructParameter<TValue>& TYsonStructParameter<TValue>::DontSerializeDefault
     // We should check for equality-comparability here but it is rather hard
     // to do the deep validation.
     static_assert(
-        NPrivate::SupportsDontSerializeDefault<TValue>,
+        NPrivate::CSupportsDontSerializeDefault<TValue>,
         "DontSerializeDefault requires |Parameter| to be TString, TDuration, an arithmetic type or an optional of those");
 
     SerializeDefault_ = false;