Demonstrate issue

wire-runtime-swift/build.gradle.kts

@@ -104,7 +104,8 @@ val generateTestProtos by tasks.creating(JavaExec::class) {
   mainClass.set("com.squareup.wire.WireCompiler")
   args = listOf(
     "--proto_path=$protoPath",
-    "--swift_out=$swiftOut"
+    "--swift_out=$swiftOut",
+    "--experimental-module-manifest=$protoPath/manifest.yml"
   )
 }
 

wire-runtime-swift/src/test/proto/manifest.yml

@@ -0,0 +1,14 @@
+---
+squareup_protos_rpc:
+  roots:
+  - squareup.protos.rpc.Response
+  prunes:
+  - google.protobuf.*
+squareup_protos_sync:
+  roots:
+  - squareup.protos.sync.GetResponse
+  - squareup.protos.sync.SyncErrorCode
+  dependencies:
+  - squareup_protos_rpc
+  prunes:
+  - google.protobuf.*

wire-runtime-swift/src/test/proto/rpc/rpc.proto

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2023 Square Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+syntax = "proto2";
+
+package squareup.protos.rpc;
+
+message Response {
+  optional string something = 1;
+}

wire-runtime-swift/src/test/proto/rpc/sync.proto

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2023 Square Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+syntax = "proto2";
+
+package squareup.protos.sync;
+
+import "rpc/rpc.proto";
+
+enum SyncErrorCode {
+  SESSION_EXPIRED      = 1;
+  UNAUTHORIZED         = 2;
+}
+
+message GetResponse {
+  optional string name = 1;
+  optional SyncErrorCode sync_error_code = 2;
+}
+
+extend squareup.protos.rpc.Response {
+  optional SyncErrorCode sync_error_code = 3;
+}