[netif] change UnsubscribeAllNodesMulticast() to return void (#4942)

src/core/net/netif.cpp

@@ -153,9 +153,8 @@ exit:
     return;
 }
 
-otError Netif::UnsubscribeAllNodesMulticast(void)
+void Netif::UnsubscribeAllNodesMulticast(void)
 {
-    otError                      error = OT_ERROR_NONE;
     NetifMulticastAddress *      prev;
     const NetifMulticastAddress &linkLocalAllNodesAddress =
         static_cast<NetifMulticastAddress &>(const_cast<otNetifMulticastAddress &>(kLinkLocalAllNodesMulticastAddress));
@@ -166,7 +165,7 @@ otError Netif::UnsubscribeAllNodesMulticast(void)
     //
     //    LinkLocalAll -> RealmLocalAll -> RealmLocalAllMpl.
 
-    SuccessOrExit(error = mMulticastAddresses.Find(linkLocalAllNodesAddress, prev));
+    SuccessOrExit(mMulticastAddresses.Find(linkLocalAllNodesAddress, prev));
 
     // This method MUST be called after `UnsubscribeAllRoutersMulticast().
     // Verify this by checking the chain at the end of the list only
@@ -198,7 +197,7 @@ otError Netif::UnsubscribeAllNodesMulticast(void)
     }
 
 exit:
-    return error;
+    return;
 }
 
 otError Netif::SubscribeAllRoutersMulticast(void)

src/core/net/netif.hpp

@@ -395,11 +395,8 @@ protected:
      *
      * @note This method MUST be called after `UnsubscribeAllRoutersMulticast()` or its behavior is undefined
      *
-     * @retval OT_ERROR_NONE          Successfully unsubscribed from all addresses.
-     * @retval OT_ERROR_NOT_FOUND     The multicast addresses were not found.
-     *
      */
-    otError UnsubscribeAllNodesMulticast(void);
+    void UnsubscribeAllNodesMulticast(void);
 
 private:
     enum

src/core/thread/thread_netif.cpp

@@ -170,7 +170,7 @@ void ThreadNetif::Down(void)
     RemoveAllExternalUnicastAddresses();
     UnsubscribeAllExternalMulticastAddresses();
     IgnoreError(UnsubscribeAllRoutersMulticast());
-    IgnoreError(UnsubscribeAllNodesMulticast());
+    UnsubscribeAllNodesMulticast();
 
     mIsUp = false;
     Get<MeshForwarder>().Stop();

tests/unit/test_netif.cpp

@@ -51,8 +51,8 @@ public:
 
     // Provide `protected` methods in `Netif` as `public` from `TestNetif`
     // so that we can verify their behavior in this test
-    void    SubscribeAllNodesMulticast(void) { Ip6::Netif::SubscribeAllNodesMulticast(); }
-    otError UnsubscribeAllNodesMulticast(void) { return Ip6::Netif::UnsubscribeAllNodesMulticast(); }
+    void SubscribeAllNodesMulticast(void) { Ip6::Netif::SubscribeAllNodesMulticast(); }
+    void UnsubscribeAllNodesMulticast(void) { Ip6::Netif::UnsubscribeAllNodesMulticast(); }
 };
 
 // This function verifies the multicast addresses on Netif matches the list of given addresses.
@@ -141,11 +141,11 @@ void TestNetifMulticastAddresses(void)
     netif.SubscribeMulticast(netifAddress);
     VerifyMulticastAddressList(netif, &addresses[2], 4);
 
-    SuccessOrQuit(netif.UnsubscribeAllNodesMulticast(), "UnsubscribeAllNodesMulticast() failed");
+    netif.UnsubscribeAllNodesMulticast();
     VerifyMulticastAddressList(netif, &addresses[5], 1);
 
-    VerifyOrQuit(netif.UnsubscribeAllNodesMulticast() == OT_ERROR_NOT_FOUND,
-                 "UnsubscribeAllNodesMulticast() did not fail when not subscribed");
+    netif.UnsubscribeAllNodesMulticast();
+    VerifyMulticastAddressList(netif, &addresses[5], 1);
 
     IgnoreError(address.FromString(kTestAddress2));
     SuccessOrQuit(netif.SubscribeExternalMulticast(address), "SubscribeExternalMulticast() failed");
@@ -190,7 +190,7 @@ void TestNetifMulticastAddresses(void)
     netif.UnsubscribeMulticast(netifAddress);
     VerifyMulticastAddressList(netif, &addresses[2], 3);
 
-    SuccessOrQuit(netif.UnsubscribeAllNodesMulticast(), "UnsubscribeAllNodesMulticast() failed");
+    netif.UnsubscribeAllNodesMulticast();
     VerifyMulticastAddressList(netif, NULL, 0);
 
     // The first five elements in `addresses[]` are the default/fixed addresses: