Add syntax='proto2' when using protobuf 3

proto/CMakeLists.txt

+execute_process(COMMAND ${PROTOBUF_PROTOC_EXECUTABLE} --version
+	OUTPUT_VARIABLE PROTOBUF_VERSION)
+string(REPLACE "libprotoc " "" PROTOBUF_VERSION ${PROTOBUF_VERSION})
+
+set(PROTOBUF_3 OFF)
+if (${PROTOBUF_VERSION} VERSION_GREATER "3.0.0" OR ${PROTOBUF_VERSION} VERSION_EQUAL "3.0.0")
+    set(PROTOBUF_3 ON)
+endif()
+
 set(proto_filenames
     DataConfig.proto
     DataFormat.proto
@@ -11,8 +20,12 @@ set(real_proto_files)
 # TODO(yuyang18): Some internal proto will also be depended on.
 #                 Find a way to automatically calculate all depends.
 foreach(filename ${proto_filenames})
+    set(PROTOBUF_3_FLAGS "")
+    if (PROTOBUF_3)
+        set(PROTOBUF_3_FLAGS "-Dproto3")
+    endif()
     add_custom_command(OUTPUT ${filename}
-        COMMAND ${M4_EXECUTABLE} -Dreal=${ACCURACY} -I '${INTERNAL_PROTO_PATH}'
+	COMMAND ${M4_EXECUTABLE} -Dreal=${ACCURACY} ${PROTOBUF_3_FLAGS} -I '${INTERNAL_PROTO_PATH}'
               ${PROJ_ROOT}/proto/${filename}.m4 > ${filename}
         DEPENDS ${PROJ_ROOT}/proto/${filename}.m4
         COMMENT "Generate ${filename}")

proto/DataConfig.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 package paddle;
 

proto/DataFormat.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 package paddle;
 

proto/ModelConfig.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 import "ParameterConfig.proto";
 

proto/ParameterConfig.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 package paddle;
 

proto/ParameterService.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 import "ParameterConfig.proto";
 import "TrainerConfig.proto";
@@ -20,7 +21,6 @@ package paddle;
 /**
  * Various structs for communicating with parameter server
  */
-
 enum ParameterUpdateMode {
   // Set parameter
    PSERVER_UPDATE_MODE_SET_PARAM = 0;//use local param

proto/TrainerConfig.proto.m4

@@ -11,6 +11,7 @@ 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. */
+ifdef(`proto3', `syntax = "proto2";')
 
 import "DataConfig.proto";
 import "ModelConfig.proto";