From dbc7e4e527e4589ea28a7e55d098cd58a7287579 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Fri, 18 Oct 2019 09:25:51 -0700
Subject: [PATCH] Fabric: More type asserts in ConcreteComponentDescriptor

Summary:
`ConcreteComponentDescriptor` is a major place where dynamic dispatch calls end up. We see some amount of crashes that can be caused by an invalid pointer to a ComponentDescriptor, those checks can help verify this theory. Anyway, it's a good practice to fail earlier.

Changelog: [Internal] - Stability improvements (Fabric)

Reviewed By: sammy-SC

Differential Revision: D17991515

fbshipit-source-id: 1cac372a12b49430a3d1db66c8fc673e6adc32e9
---
 .../ConcreteComponentDescriptor.h             | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h b/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
index 61e616eff49..f87bc5051a5 100644
--- a/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
+++ b/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
@@ -77,6 +77,10 @@ class ConcreteComponentDescriptor : public ComponentDescriptor {
   UnsharedShadowNode cloneShadowNode(
       const ShadowNode &sourceShadowNode,
       const ShadowNodeFragment &fragment) const override {
+    assert(
+        dynamic_cast<ConcreteShadowNode const *>(&sourceShadowNode) &&
+        "Provided `sourceShadowNode` has an incompatible type.");
+
     auto shadowNode = std::make_shared<ShadowNodeT>(sourceShadowNode, fragment);
 
     adopt(shadowNode);
@@ -86,6 +90,10 @@ class ConcreteComponentDescriptor : public ComponentDescriptor {
   void appendChild(
       const SharedShadowNode &parentShadowNode,
       const SharedShadowNode &childShadowNode) const override {
+    assert(
+        dynamic_cast<ConcreteShadowNode const *>(parentShadowNode.get()) &&
+        "Provided `parentShadowNode` has an incompatible type.");
+
     auto concreteParentShadowNode =
         std::static_pointer_cast<const ShadowNodeT>(parentShadowNode);
     auto concreteNonConstParentShadowNode =
@@ -96,6 +104,11 @@ class ConcreteComponentDescriptor : public ComponentDescriptor {
   virtual SharedProps cloneProps(
       const SharedProps &props,
       const RawProps &rawProps) const override {
+    assert(
+        !props ||
+        dynamic_cast<ConcreteProps const *>(props.get()) &&
+            "Provided `props` has an incompatible type.");
+
     if (rawProps.isEmpty()) {
       return props ? props : ShadowNodeT::defaultSharedProps();
     }
@@ -132,6 +145,12 @@ class ConcreteComponentDescriptor : public ComponentDescriptor {
       return nullptr;
     }
 
+    assert(previousState && "Provided `previousState` is nullptr.");
+    assert(data && "Provided `data` is nullptr.");
+    assert(
+        dynamic_cast<ConcreteState const *>(previousState.get()) &&
+        "Provided `previousState` has an incompatible type.");
+
     return std::make_shared<const ConcreteState>(
         std::move(*std::static_pointer_cast<ConcreteStateData>(data)),
         *std::static_pointer_cast<const ConcreteState>(previousState));