From 97ecb5eb1903eefb1d7bc05361b741bca71df9f6 Mon Sep 17 00:00:00 2001
From: Joshua Gross <joshuagross@fb.com>
Date: Tue, 9 Feb 2021 22:40:17 -0800
Subject: [PATCH] StubViewTree: ensure nodes don't have parents when they're
 inserted

Summary:
iOS and Android platform code already explicitly check this invariant: nodes cannot have parents when they're inserted into the View hierarchy.

Check this in the core so we get these checks in unit tests, and earlier in the core before platform code runs.

Changelog: [Internal]

Reviewed By: shergin, mdvacca

Differential Revision: D26331842

fbshipit-source-id: c12bc9066d280cb85ccc9e754c9fa475927e6080
---
 ReactCommon/react/renderer/mounting/StubView.h       | 3 +++
 ReactCommon/react/renderer/mounting/StubViewTree.cpp | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/ReactCommon/react/renderer/mounting/StubView.h b/ReactCommon/react/renderer/mounting/StubView.h
index ca433c953b3..a721c57c74d 100644
--- a/ReactCommon/react/renderer/mounting/StubView.h
+++ b/ReactCommon/react/renderer/mounting/StubView.h
@@ -18,6 +18,8 @@
 namespace facebook {
 namespace react {
 
+static const int NO_VIEW_TAG = -1;
+
 class StubView final {
  public:
   using Shared = std::shared_ptr<StubView>;
@@ -38,6 +40,7 @@ class StubView final {
   LayoutMetrics layoutMetrics;
   State::Shared state;
   std::vector<StubView::Shared> children;
+  Tag parentTag{NO_VIEW_TAG};
 };
 
 bool operator==(StubView const &lhs, StubView const &rhs);
diff --git a/ReactCommon/react/renderer/mounting/StubViewTree.cpp b/ReactCommon/react/renderer/mounting/StubViewTree.cpp
index bc51d102603..306076bdd73 100644
--- a/ReactCommon/react/renderer/mounting/StubViewTree.cpp
+++ b/ReactCommon/react/renderer/mounting/StubViewTree.cpp
@@ -90,6 +90,7 @@ void StubViewTree::mutate(ShadowViewMutationList const &mutations) {
         auto childTag = mutation.newChildShadowView.tag;
         STUB_VIEW_ASSERT(registry.find(childTag) != registry.end());
         auto childStubView = registry[childTag];
+        STUB_VIEW_ASSERT(childStubView->parentTag == NO_VIEW_TAG);
         childStubView->update(mutation.newChildShadowView);
         STUB_VIEW_LOG({
           LOG(ERROR) << "StubView: Insert: " << childTag << " into "
@@ -97,6 +98,7 @@ void StubViewTree::mutate(ShadowViewMutationList const &mutations) {
                      << parentStubView->children.size() << " children)";
         });
         STUB_VIEW_ASSERT(parentStubView->children.size() >= mutation.index);
+        childStubView->parentTag = parentTag;
         parentStubView->children.insert(
             parentStubView->children.begin() + mutation.index, childStubView);
         break;
@@ -116,6 +118,7 @@ void StubViewTree::mutate(ShadowViewMutationList const &mutations) {
         STUB_VIEW_ASSERT(parentStubView->children.size() > mutation.index);
         STUB_VIEW_ASSERT(registry.find(childTag) != registry.end());
         auto childStubView = registry[childTag];
+        STUB_VIEW_ASSERT(childStubView->parentTag == parentTag);
         bool childIsCorrect =
             parentStubView->children.size() > mutation.index &&
             parentStubView->children[mutation.index]->tag == childStubView->tag;
@@ -133,6 +136,7 @@ void StubViewTree::mutate(ShadowViewMutationList const &mutations) {
                      << ": " << strChildList;
         });
         STUB_VIEW_ASSERT(childIsCorrect);
+        childStubView->parentTag = NO_VIEW_TAG;
         parentStubView->children.erase(
             parentStubView->children.begin() + mutation.index);
         break;