electron/patches/v8/revert_api_delete_deprecated_attachcppheap_and_detachcppheap.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Charles Kerr <charles@charleskerr.com>
Date: Thu, 6 Mar 2025 14:31:19 -0600
Subject: Revert "[api] Delete deprecated AttachCppHeap and DetachCppHeap"

Restore this API because Node.js needs it.

This patch can be removed after an upstream fix lands in Node.js,
e.g. in https://github.com/nodejs/node-v8/tree/canary

diff --git a/include/v8-isolate.h b/include/v8-isolate.h
index 97f1030dd2ca47ca4b58ac64e2e11e615bc46130..24ef6b5e0af63179e557b9896134838e112c59db 100644
--- a/include/v8-isolate.h
+++ b/include/v8-isolate.h
@@ -1172,6 +1172,28 @@ class V8_EXPORT Isolate {
    */
   void SetEmbedderRootsHandler(EmbedderRootsHandler* handler);
 
+  /**
+   * Attaches a managed C++ heap as an extension to the JavaScript heap. The
+   * embedder maintains ownership of the CppHeap. At most one C++ heap can be
+   * attached to V8.
+   *
+   * Multi-threaded use requires the use of v8::Locker/v8::Unlocker, see
+   * CppHeap.
+   *
+   * If a CppHeap is set via CreateParams, then this call is a noop.
+   */
+  V8_DEPRECATED("Set the heap on Isolate creation using CreateParams instead.")
+  void AttachCppHeap(CppHeap*);
+
+  /**
+   * Detaches a managed C++ heap if one was attached using `AttachCppHeap()`.
+   *
+   * If a CppHeap is set via CreateParams, then this call is a noop.
+   */
+  V8_DEPRECATED(
+      "The CppHeap gets detached automatically during Isolate tear down.")
+  void DetachCppHeap();
+
   using ReleaseCppHeapCallback = void (*)(std::unique_ptr<CppHeap>);
 
   /**
@@ -1219,7 +1241,6 @@ class V8_EXPORT Isolate {
   class V8_DEPRECATED("AtomicsWaitWakeHandle is unused and will be removed.")
 #endif
   V8_EXPORT AtomicsWaitWakeHandle {
-
    public:
     /**
      * Stop this `Atomics.wait()` call and call the |AtomicsWaitCallback|
diff --git a/src/api/api.cc b/src/api/api.cc
index 64044e9cf44d401c249787feafb651688ee0d9f9..1677e54b188b6a1699370d8cff37d2acf2933f38 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -9876,6 +9876,16 @@ void Isolate::SetEmbedderRootsHandler(EmbedderRootsHandler* handler) {
   i_isolate->heap()->SetEmbedderRootsHandler(handler);
 }
 
+void Isolate::AttachCppHeap(CppHeap* cpp_heap) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+  i_isolate->heap()->AttachCppHeap(cpp_heap);
+}
+
+void Isolate::DetachCppHeap() {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+  i_isolate->heap()->DetachCppHeap();
+}
+
 CppHeap* Isolate::GetCppHeap() const {
   const i::Isolate* i_isolate = reinterpret_cast<const i::Isolate*>(this);
   return i_isolate->heap()->cpp_heap();
diff --git a/src/heap/cppgc-js/cpp-heap.cc b/src/heap/cppgc-js/cpp-heap.cc
index e033791ca1cdeba4a304e69b922d4169a22f9caa..706f81f7bbc1b5a7a1b73afe018b0b2c0184d9ef 100644
--- a/src/heap/cppgc-js/cpp-heap.cc
+++ b/src/heap/cppgc-js/cpp-heap.cc
@@ -513,6 +513,11 @@ CppHeap::CppHeap(
 }
 
 CppHeap::~CppHeap() {
+  if (isolate_) {
+    // TODO(ahaas): Delete this code once `v8::Isolate::DetachCppHeap` has been
+    // deleted.
+    isolate_->heap()->DetachCppHeap();
+  }
   Terminate();
 }
 
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index cedf308a6042cc45241d4ee2731d2ee240ee8d9f..794c6380db4a669e7a83f6cce1db1dbe4fcde972 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -6065,6 +6065,21 @@ void Heap::AttachCppHeap(v8::CppHeap* cpp_heap) {
   cpp_heap_ = cpp_heap;
 }
 
+void Heap::DetachCppHeap() {
+  // The API function should be a noop in case a CppHeap was passed on Isolate
+  // creation.
+  if (owning_cpp_heap_) {
+    return;
+  }
+
+  // The CppHeap may have been detached already.
+  if (!cpp_heap_) return;
+
+  CppHeap::From(cpp_heap_)->StartDetachingIsolate();
+  CppHeap::From(cpp_heap_)->DetachIsolate();
+  cpp_heap_ = nullptr;
+}
+
 std::optional<StackState> Heap::overridden_stack_state() const {
   if (!embedder_stack_state_origin_) return {};
   return embedder_stack_state_;
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 200a3bdcd563a54b9fbd6c7ca007fb940b1a9451..0946601a9c25a03a830fb6a8fb5389057bfe5d33 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1108,6 +1108,9 @@ class Heap final {
   // Unified heap (C++) support. ===============================================
   // ===========================================================================
 
+  V8_EXPORT_PRIVATE void AttachCppHeap(v8::CppHeap* cpp_heap);
+  V8_EXPORT_PRIVATE void DetachCppHeap();
+
   v8::CppHeap* cpp_heap() const { return cpp_heap_; }
 
   std::optional<StackState> overridden_stack_state() const;
@@ -1649,8 +1652,6 @@ class Heap final {
  private:
   class AllocationTrackerForDebugging;
 
-  void AttachCppHeap(v8::CppHeap* cpp_heap);
-
   using ExternalStringTableUpdaterCallback =
       Tagged<String> (*)(Heap* heap, FullObjectSlot pointer);