test back with only invocable

Author: caspernorrbin

src/hotspot/share/utilities/rbTree.hpp

@@ -211,16 +211,26 @@ class AbstractRBTree {
 
   // static constexpr bool HasNodeVerifier = HasNodeVerifierImpl<COMPARATOR>;
 
-template<typename, typename = void>
-struct has_node_verifier : std::false_type { };
+  // template<typename, typename = void>
+  // struct has_node_verifier : std::false_type { };
 
-template <typename CMP>
-struct has_node_verifier<CMP, std::void_t<decltype(&CMP::less_than)>> // detected
-    : std::bool_constant<std::is_invocable_r_v<
-          bool, decltype(&CMP::less_than), const NodeType *, const NodeType *>> {
-};
+  // template <typename CMP>
+  // struct has_node_verifier<CMP, std::void_t<decltype(&CMP::less_than)>>
+  //     : std::bool_constant<std::is_invocable_r_v<
+  //           bool, decltype(&CMP::less_than), const NodeType *, const NodeType *>> {
+  // };
+
+  // static constexpr bool HasNodeVerifier = has_node_verifier<COMPARATOR>::value;
+
+  template <typename /*T*/, typename = void>
+  static constexpr bool has_node_verifier_v = false;
+
+  template <typename CMP>
+  static constexpr bool has_node_verifier_v<CMP, std::void_t<decltype(&CMP::less_than)>> =
+      std::is_invocable_r_v<bool, decltype(&CMP::less_than), const NodeType*, const NodeType*>;
+
+  static constexpr bool HasNodeVerifier = has_node_verifier_v<COMPARATOR>;
 
-static constexpr bool HasNodeVerifier = has_node_verifier<COMPARATOR>::value;
 
 RBTreeOrdering cmp(const K &a, const NodeType *b) const {
   if constexpr (HasNodeComparator) {