From 88b97f5367693dc6d83b35b2761a6069f1a4b720 Mon Sep 17 00:00:00 2001
From: Ali Mohammad Pur <ali.mpfard@gmail.com>
Date: Tue, 20 Apr 2021 13:01:27 +0430
Subject: [PATCH] AK: Make IntrusiveList work with NonnullRefPtr's

---
 AK/IntrusiveList.h | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/AK/IntrusiveList.h b/AK/IntrusiveList.h
index 082a93ac3b..0282f5fad2 100644
--- a/AK/IntrusiveList.h
+++ b/AK/IntrusiveList.h
@@ -33,15 +33,32 @@
 
 namespace AK {
 
+namespace Detail {
 template<typename T, typename Container = RawPtr<T>>
 class IntrusiveListNode;
 
+template<typename T, typename Container>
+struct SubstituteIntrusiveListNodeContainerType {
+    using Type = Container;
+};
+
+template<typename T>
+struct SubstituteIntrusiveListNodeContainerType<T, NonnullRefPtr<T>> {
+    using Type = RefPtr<T>;
+};
+}
+
+template<typename T, typename Container = RawPtr<T>>
+using IntrusiveListNode = Detail::IntrusiveListNode<T, typename Detail::SubstituteIntrusiveListNodeContainerType<T, Container>::Type>;
+
 template<typename T, typename Container>
 class IntrusiveListStorage {
 private:
-    friend class IntrusiveListNode<T, Container>;
+    friend class Detail::IntrusiveListNode<T, Container>;
+
     template<class T_, typename Container_, IntrusiveListNode<T_, Container_> T_::*member>
     friend class IntrusiveList;
+
     IntrusiveListNode<T, Container>* m_first { nullptr };
     IntrusiveListNode<T, Container>* m_last { nullptr };
 };
@@ -132,6 +149,8 @@ template<typename Contained>
 struct SelfReferenceIfNeeded<Contained, true> {
 };
 
+namespace Detail {
+
 template<typename T, typename Container>
 class IntrusiveListNode {
 public:
@@ -141,15 +160,22 @@ public:
 
     static constexpr bool IsRaw = IsPointer<Container>;
 
+    // Note: For some reason, clang does not consider `member` as declared here, and as declared above (`IntrusiveListNode<T, Container> T::*`)
+    //       to be of equal types. so for now, just make the members public on clang.
+#ifndef __clang__
 private:
     template<class T_, typename Container_, IntrusiveListNode<T_, Container_> T_::*member>
-    friend class IntrusiveList;
+    friend class ::AK::IntrusiveList;
+#endif
+
     IntrusiveListStorage<T, Container>* m_storage = nullptr;
     IntrusiveListNode<T, Container>* m_next = nullptr;
     IntrusiveListNode<T, Container>* m_prev = nullptr;
     SelfReferenceIfNeeded<Container, IsRaw> m_self;
 };
 
+}
+
 template<class T, typename Container, IntrusiveListNode<T, Container> T::*member>
 inline typename IntrusiveList<T, Container, member>::Iterator& IntrusiveList<T, Container, member>::Iterator::erase()
 {
@@ -309,6 +335,8 @@ inline T* IntrusiveList<T, Container, member>::node_to_value(IntrusiveListNode<T
     return bit_cast<T*>(bit_cast<unsigned char*>(&node) - bit_cast<unsigned char*>(member));
 }
 
+namespace Detail {
+
 template<typename T, typename Container>
 inline IntrusiveListNode<T, Container>::~IntrusiveListNode()
 {
@@ -341,12 +369,11 @@ inline bool IntrusiveListNode<T, Container>::is_in_list() const
     return m_storage != nullptr;
 }
 
-// Specialise IntrusiveList(Node) for NonnullRefPtr
+}
+
+// Specialise IntrusiveList for NonnullRefPtr
 // By default, intrusive lists cannot contain null entries anyway, so switch to RefPtr
 // and just make the user-facing functions deref the pointers.
-template<typename T>
-struct IntrusiveListNode<T, NonnullRefPtr<T>> : public IntrusiveListNode<T, RefPtr<T>> {
-};
 
 template<class T, IntrusiveListNode<T, NonnullRefPtr<T>> T::*member>
 class IntrusiveList<T, NonnullRefPtr<T>, member> : public IntrusiveList<T, RefPtr<T>, member> {