From 81041edfaea0f9ff7f724a0079542abd544f62e4 Mon Sep 17 00:00:00 2001
From: Mike Kruskal <mkruskal@google.com>
Date: Tue, 28 May 2024 14:32:15 -0700
Subject: [PATCH] Fix latent bug disallowing certain MessageSet extensions

PiperOrigin-RevId: 638025707
---
 src/google/protobuf/descriptor.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/google/protobuf/descriptor.cc b/src/google/protobuf/descriptor.cc
index 6bcb556950..eb45d425ed 100644
--- a/src/google/protobuf/descriptor.cc
+++ b/src/google/protobuf/descriptor.cc
@@ -7340,7 +7340,8 @@ void DescriptorBuilder::CrossLinkField(FieldDescriptor* field,
       // from other extendees (< 2^29). If unknown deps are allowed, we may not
       // have that information, and wrongly deem the extension as invalid.
       auto skip_check = get_allow_unknown(pool_) &&
-                        proto.extendee() == "google.protobuf.bridge.MessageSet";
+                        absl::StripPrefix(proto.extendee(), ".") ==
+                            "google.protobuf.bridge.MessageSet";
       if (!skip_check) {
         AddError(field->full_name(), proto,
                  DescriptorPool::ErrorCollector::NUMBER, [&] {