From 51bf55ea49655a0962c9bd78c2d64ba183bfbb8c Mon Sep 17 00:00:00 2001
From: qm3ster <qm3ster@gmail.com>
Date: Fri, 23 Apr 2021 02:53:44 +0300
Subject: [PATCH] Set `opts` if calling `subscribeMany` with 1 topic

---
 src/response_options.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/response_options.rs b/src/response_options.rs
index 74e0f8f..ef1f163 100644
--- a/src/response_options.rs
+++ b/src/response_options.rs
@@ -172,7 +172,12 @@ impl ResponseOptionsBuilder {
 
     /// Sets a single set of subscribe options - for a call to subscribe_many()
     pub fn subscribe_many_options(&mut self, opts: &[SubscribeOptions]) -> &mut Self {
-        self.data.sub_opts = Some(opts.iter().map(|opt| opt.copts).collect());
+        match opts {
+            [] => {}
+            // This is necessary, as the `MQTTAsync_subscribeMany` paho.mqtt.c function uses `opts` over `optlist` when `count <= 1`
+            [opts] => self.copts.subscribeOptions = opts.copts,
+            _ => self.data.sub_opts = Some(opts.iter().map(|opt| opt.copts).collect())
+        }
         self
     }