From 934f36d049d28b112f0a237ad04e2c9ce8ccb459 Mon Sep 17 00:00:00 2001
From: Marvin Hagemeister <hello@marvinh.dev>
Date: Sun, 24 Jan 2021 00:20:47 +0100
Subject: [PATCH 1/2] Fix HTML comments breaking hydration

This PR resolves a regression when react-dom/server was used to render
a Preact app. It was introduced in #2942
---
 src/diff/index.js            | 8 +++++++-
 test/browser/hydrate.test.js | 6 ++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/diff/index.js b/src/diff/index.js
index e4cf4c033f..b0bcd18810 100644
--- a/src/diff/index.js
+++ b/src/diff/index.js
@@ -318,7 +318,13 @@ function diffElementNodes(
 			//
 			// Note: This takes advantage of Text nodes having `.localName=undefined`,
 			// which is loosely equal to Text VNodes' `.type=null`. Elements use string equality.
-			if (child != null && (dom == child || child.localName == nodeType)) {
+			if (
+				child != null &&
+				((newVNode.type === null
+					? child.nodeType === 3
+					: child.localName === newVNode.type) ||
+					dom == child)
+			) {
 				dom = child;
 				excessDomChildren[i] = null;
 				break;
diff --git a/test/browser/hydrate.test.js b/test/browser/hydrate.test.js
index a9ddd92a5f..5f6e537f95 100644
--- a/test/browser/hydrate.test.js
+++ b/test/browser/hydrate.test.js
@@ -445,4 +445,10 @@ describe('hydrate()', () => {
 			'<p class="hi">hello baz</p><p class="hi">hello bar</p>'
 		);
 	});
+
+	it('should skip comment nodes', () => {
+		scratch.innerHTML = '<p>hello <!-- c -->foo</p>';
+		hydrate(<p>hello {'foo'}</p>, scratch);
+		expect(scratch.innerHTML).to.equal('<p>hello foo</p>');
+	});
 });

From 5583b467d5b4bf725b11521b53d29158e5f4f20f Mon Sep 17 00:00:00 2001
From: Marvin Hagemeister <hello@marvinh.dev>
Date: Sun, 24 Jan 2021 00:49:35 +0100
Subject: [PATCH 2/2] golf -2B

---
 src/diff/index.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/diff/index.js b/src/diff/index.js
index b0bcd18810..da767fff04 100644
--- a/src/diff/index.js
+++ b/src/diff/index.js
@@ -320,9 +320,9 @@ function diffElementNodes(
 			// which is loosely equal to Text VNodes' `.type=null`. Elements use string equality.
 			if (
 				child != null &&
-				((newVNode.type === null
+				((nodeType === null
 					? child.nodeType === 3
-					: child.localName === newVNode.type) ||
+					: child.localName === nodeType) ||
 					dom == child)
 			) {
 				dom = child;