11 files changed, 378 insertions, 7 deletions
diff --git a/objectivec/Tests/GPBMessageTests+Runtime.m b/objectivec/Tests/GPBMessageTests+Runtime.m
index 2cf9ccef..0058311b 100644
--- a/objectivec/Tests/GPBMessageTests+Runtime.m
+++ b/objectivec/Tests/GPBMessageTests+Runtime.m
@@ -36,6 +36,7 @@
 
 #import "google/protobuf/MapUnittest.pbobjc.h"
 #import "google/protobuf/Unittest.pbobjc.h"
+#import "google/protobuf/UnittestCycle.pbobjc.h"
 #import "google/protobuf/UnittestObjcStartup.pbobjc.h"
 #import "google/protobuf/UnittestRuntimeProto2.pbobjc.h"
 #import "google/protobuf/UnittestRuntimeProto3.pbobjc.h"
@@ -49,11 +50,24 @@
 // specific.
 
 - (void)testStartupOrdering {
-  // Just have to create a message.  Nothing else uses the classes from
-  // this file, so the first selector invoked on the class will initialize
-  // it, which also initializes the root.
+  // Message class/Root class initialization is a little tricky, so these just
+  // create some possible patterns that can be a problem. The messages don't
+  // have to be exercised, just creating them is enough to test.  If there
+  // is a problem, the runtime should assert or hang.
+  //
+  // Note: the messages from these proto files should not be used in any other
+  // tests, that way when they are referenced here it will be the first use and
+  // initialization will take place now.
+
   TestObjCStartupMessage *message = [TestObjCStartupMessage message];
   XCTAssertNotNil(message);
+
+  CycleBaz *baz = [CycleBaz message];
+  CycleBar *bar = [CycleBar message];
+  CycleFoo *foo = [CycleFoo message];
+  XCTAssertNotNil(baz);
+  XCTAssertNotNil(bar);
+  XCTAssertNotNil(foo);
 }
 
 - (void)testProto2HasMethodSupport {
diff --git a/objectivec/Tests/GPBUnittestProtos.m b/objectivec/Tests/GPBUnittestProtos.m
index d19beee9..7b938e72 100644
--- a/objectivec/Tests/GPBUnittestProtos.m
+++ b/objectivec/Tests/GPBUnittestProtos.m
@@ -62,3 +62,11 @@
 #import "google/protobuf/UnittestPreserveUnknownEnum.pbobjc.m"
 #import "google/protobuf/UnittestRuntimeProto2.pbobjc.m"
 #import "google/protobuf/UnittestRuntimeProto3.pbobjc.m"
+
+#import "google/protobuf/UnittestExtensionChainA.pbobjc.m"
+#import "google/protobuf/UnittestExtensionChainB.pbobjc.m"
+#import "google/protobuf/UnittestExtensionChainC.pbobjc.m"
+#import "google/protobuf/UnittestExtensionChainD.pbobjc.m"
+#import "google/protobuf/UnittestExtensionChainE.pbobjc.m"
+// See GPBUnittestProtos2.m for for "UnittestExtensionChainF.pbobjc.m"
+#import "google/protobuf/UnittestExtensionChainG.pbobjc.m"
diff --git a/objectivec/Tests/GPBUnittestProtos2.m b/objectivec/Tests/GPBUnittestProtos2.m
new file mode 100644
index 00000000..ef9f0702
--- /dev/null
+++ b/objectivec/Tests/GPBUnittestProtos2.m
@@ -0,0 +1,34 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This one file in the chain tests is compiled by itself to ensure if was
+// generated with the extra #imports needed to pull in the indirect Root class
+// used in its Root registry.
+#import "google/protobuf/UnittestExtensionChainF.pbobjc.m"
diff --git a/objectivec/Tests/unittest_cycle.proto b/objectivec/Tests/unittest_cycle.proto
index 5f6f56a1..afc1b0fe 100644
--- a/objectivec/Tests/unittest_cycle.proto
+++ b/objectivec/Tests/unittest_cycle.proto
@@ -31,10 +31,8 @@ syntax = "proto2";
 
 package protobuf_unittest;
 
-// Cycles in the Message graph can cause problems for the mutable classes
-// since the properties on the mutable class change types. This file just
-// needs to generate source, and that source must compile, to ensure the
-// generated source works for this sort of case.
+// Cycles in the Message graph can cause problems for message class
+// initialization order.
 
 // You can't make a object graph that spans files, so this can only be done
 // within a single proto file.
diff --git a/objectivec/Tests/unittest_extension_chain_a.proto b/objectivec/Tests/unittest_extension_chain_a.proto
new file mode 100644
index 00000000..6a227eb9
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_a.proto
@@ -0,0 +1,51 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "google/protobuf/unittest.proto";
+
+import "unittest_extension_chain_b.proto";
+import "unittest_extension_chain_c.proto";
+import "unittest_extension_chain_d.proto";
+
+// The Root for this file should end up adding the local extension and merging
+// in the extensions from D's Root (unittest and C will come via D's).
+
+message ChainAMessage {
+  optional ChainBMessage b = 1;
+  optional ChainCMessage c = 2;
+  optional ChainDMessage d = 3;
+}
+
+extend TestAllExtensions {
+  optional int32 chain_a_extension = 10001;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_b.proto b/objectivec/Tests/unittest_extension_chain_b.proto
new file mode 100644
index 00000000..0da7ed3e
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_b.proto
@@ -0,0 +1,47 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "google/protobuf/unittest.proto";
+
+import "unittest_extension_chain_c.proto";
+
+// The Root for this file should end up adding the local extension and merging
+// in the extensions from C's Root (unittest will come via C's).
+
+message ChainBMessage {
+  optional ChainCMessage c = 1;
+}
+
+extend TestAllExtensions {
+  optional int32 chain_b_extension = 10002;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_c.proto b/objectivec/Tests/unittest_extension_chain_c.proto
new file mode 100644
index 00000000..c702900a
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_c.proto
@@ -0,0 +1,45 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "google/protobuf/unittest.proto";
+
+// The Root for this file should end up adding the local extension and merging
+// in the extensions from unittest.proto's Root.
+
+message ChainCMessage {
+  optional int32 my_field = 1;
+}
+
+extend TestAllExtensions {
+  optional int32 chain_c_extension = 10003;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_d.proto b/objectivec/Tests/unittest_extension_chain_d.proto
new file mode 100644
index 00000000..f9abe3ba
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_d.proto
@@ -0,0 +1,49 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "google/protobuf/unittest.proto";
+
+import "unittest_extension_chain_b.proto";
+import "unittest_extension_chain_c.proto";
+
+// The root should end up needing to merge B (C will be merged into B, so it
+// doesn't need to be directly merged).
+
+message ChainDMessage {
+  optional ChainBMessage b = 1;
+  optional ChainCMessage c = 2;
+}
+
+extend TestAllExtensions {
+  optional int32 chain_d_extension = 10004;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_e.proto b/objectivec/Tests/unittest_extension_chain_e.proto
new file mode 100644
index 00000000..fe116631
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_e.proto
@@ -0,0 +1,40 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "google/protobuf/unittest.proto";
+
+// The Root for this file should end up just merging in unittest's Root.
+
+message ChainEMessage {
+  optional TestAllTypes my_field = 1;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_f.proto b/objectivec/Tests/unittest_extension_chain_f.proto
new file mode 100644
index 00000000..b9bed723
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_f.proto
@@ -0,0 +1,44 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "unittest_extension_chain_g.proto";
+
+// The Root for this file should just be merging in the extensions from C's
+// Root (because G doens't define anything itself).
+
+// The generated source will also have to directly import C's .h file so it can
+// compile the reference to C's Root class.
+
+message ChainFMessage {
+  optional ChainGMessage g = 1;
+}
diff --git a/objectivec/Tests/unittest_extension_chain_g.proto b/objectivec/Tests/unittest_extension_chain_g.proto
new file mode 100644
index 00000000..aee827b1
--- /dev/null
+++ b/objectivec/Tests/unittest_extension_chain_g.proto
@@ -0,0 +1,41 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package protobuf_unittest;
+
+import "unittest_extension_chain_c.proto";
+
+// The Root for this file should just be merging in the extensions from C's
+// Root.
+
+message ChainGMessage {
+  optional ChainCMessage c = 1;
+}