From 7be2ff5feb2e4584be7d666a19e85a22e7ade956 Mon Sep 17 00:00:00 2001
From: Pierre-Yves Gerardy <py@py.gy>
Date: Sun, 26 Mar 2017 22:07:49 +0200
Subject: [PATCH] Strengthen the self-return prevention logic (for recycled
 nodes and updates)

---
 render/render.js               |  3 ++-
 render/tests/test-component.js | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/render/render.js b/render/render.js
index 835c2f5f..5e238d56 100644
--- a/render/render.js
+++ b/render/render.js
@@ -119,12 +119,12 @@ module.exports = function($window) {
 		if (vnode.attrs != null) initLifecycle(vnode.attrs, vnode, hooks)
 		initLifecycle(vnode.state, vnode, hooks)
 		vnode.instance = Vnode.normalize(vnode.state.view(vnode))
+		if (vnode.instance === vnode) throw Error("A view cannot return the vnode it received as argument")
 		sentinel.$$reentrantLock$$ = null
 	}
 	function createComponent(parent, vnode, hooks, ns, nextSibling) {
 		initComponent(vnode, hooks)
 		if (vnode.instance != null) {
-			if (vnode.instance === vnode) throw Error("A view cannot return the vnode it received as arguments")
 			var element = createNode(parent, vnode.instance, hooks, ns, nextSibling)
 			vnode.dom = vnode.instance.dom
 			vnode.domSize = vnode.dom != null ? vnode.instance.domSize : 0
@@ -317,6 +317,7 @@ module.exports = function($window) {
 			initComponent(vnode, hooks)
 		} else {
 			vnode.instance = Vnode.normalize(vnode.state.view(vnode))
+			if (vnode.instance === vnode) throw Error("A view cannot return the vnode it received as argument")
 			if (vnode.attrs != null) updateLifecycle(vnode.attrs, vnode, hooks)
 			updateLifecycle(vnode.state, vnode, hooks)
 		}
diff --git a/render/tests/test-component.js b/render/tests/test-component.js
index a3429cee..8fccb9c3 100644
--- a/render/tests/test-component.js
+++ b/render/tests/test-component.js
@@ -260,8 +260,9 @@ o.spec("component", function() {
 
 					o(root.childNodes.length).equals(0)
 				})
-				o("throws a custom error if it returns itself", function() {
+				o("throws a custom error if it returns itself when created", function() {
 					// A view that returns its vnode would otherwise trigger an infinite loop
+					var threw = false
 					var component = createComponent({
 						view: function(vnode) {
 							return vnode
@@ -271,10 +272,41 @@ o.spec("component", function() {
 						render(root, [{tag: component}])
 					}
 					catch (e) {
+						threw = true
 						o(e instanceof Error).equals(true)
 						// Call stack exception is a RangeError
 						o(e instanceof RangeError).equals(false)
 					}
+					o(threw).equals(true)
+				})
+				o("throws a custom error if it returns itself when updated", function() {
+					// A view that returns its vnode would otherwise trigger an infinite loop
+					var threw = false
+					var init = true
+					var oninit = o.spy()
+					var component = createComponent({
+						oninit: oninit,
+						view: function(vnode) {
+							if (init) return init = false
+							else return vnode
+						}
+					})
+					render(root, [{tag: component}])
+
+					o(root.firstChild.nodeType).equals(3)
+					o(root.firstChild.nodeValue).equals("")
+
+					try {
+						render(root, [{tag: component}])
+					}
+					catch (e) {
+						threw = true
+						o(e instanceof Error).equals(true)
+						// Call stack exception is a RangeError
+						o(e instanceof RangeError).equals(false)
+					}
+					o(threw).equals(true)
+					o(oninit.callCount).equals(1)
 				})
 				o("can update when returning fragments", function() {
 					var component = createComponent({