SerializationTraits: Remove unnecessary 2nd template parameter (#31363)

include/grpcpp/impl/codegen/call_op_set.h

@@ -384,11 +384,7 @@ Status CallOpSendMessage::SendMessage(const M& message, WriteOptions options) {
   write_options_ = options;
   // Serialize immediately since we do not have access to the message pointer
   bool own_buf;
-  // TODO(vjpai): Remove the void below when possible
-  // The void in the template parameter below should not be needed
-  // (since it should be implicit) but is needed due to an observed
-  // difference in behavior between clang and gcc for certain internal users
-  Status result = SerializationTraits<M, void>::Serialize(
+  Status result = SerializationTraits<M>::Serialize(
       message, send_buf_.bbuf_ptr(), &own_buf);
   if (!own_buf) {
     send_buf_.Duplicate();
@@ -413,7 +409,7 @@ Status CallOpSendMessage::SendMessagePtr(const M* message,
     // The void in the template parameter below should not be needed
     // (since it should be implicit) but is needed due to an observed
     // difference in behavior between clang and gcc for certain internal users
-    Status result = SerializationTraits<M, void>::Serialize(
+    Status result = SerializationTraits<M>::Serialize(
         *static_cast<const M*>(message), send_buf_.bbuf_ptr(), &own_buf);
     if (!own_buf) {
       send_buf_.Duplicate();

test/cpp/util/byte_buffer_test.cc

@@ -116,8 +116,8 @@ TEST_F(ByteBufferTest, SerializationMakesCopy) {
   bool owned = false;
   ByteBuffer buffer(&slices[0], 2);
   slices.clear();
-  auto status = SerializationTraits<ByteBuffer, void>::Serialize(
-      buffer, &send_buffer, &owned);
+  auto status =
+      SerializationTraits<ByteBuffer>::Serialize(buffer, &send_buffer, &owned);
   EXPECT_TRUE(status.ok());
   EXPECT_TRUE(owned);
   EXPECT_TRUE(send_buffer.Valid());