Fix build issue in FreeRTOS+TCP QEMU demo when DHCP enabled (#1092)

* Fix build issue in QEMU demo when DHCP enabled

FreeRTOS-Plus/Demo/FreeRTOS_Plus_TCP_Echo_Posix/TCPEchoClient_SingleTasks.c

@@ -399,22 +399,22 @@
         return xReturn;
     }
 
-#endif /* ipconfigUSE_TCP */
+    #if ( ipconfigUSE_DHCP_HOOK != 0 )
+
+        #if ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 )
+            eDHCPCallbackAnswer_t xApplicationDHCPHook( eDHCPCallbackPhase_t eDHCPPhase,
+                                                        uint32_t ulIPAddress )
+        #else /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
+            eDHCPCallbackAnswer_t xApplicationDHCPHook_Multi( eDHCPCallbackPhase_t eDHCPPhase,
+                                                              struct xNetworkEndPoint * pxEndPoint,
+                                                              IP_Address_t * pxIPAddress )
+        #endif /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
+        {
+            /* Provide a stub for this function. */
+            return eDHCPContinue;
+        }
 
-#if ( ( ipconfigUSE_TCP == 1 ) && ( ipconfigUSE_DHCP_HOOK != 0 ) )
+    #endif /* if ( ipconfigUSE_DHCP_HOOK != 0 ) */
 
-    #if ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 )
-        eDHCPCallbackAnswer_t xApplicationDHCPHook( eDHCPCallbackPhase_t eDHCPPhase,
-                                                    uint32_t ulIPAddress )
-    #else /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
-        eDHCPCallbackAnswer_t xApplicationDHCPHook_Multi( eDHCPCallbackPhase_t eDHCPPhase,
-                                                          struct xNetworkEndPoint * pxEndPoint,
-                                                          IP_Address_t * pxIPAddress )
-    #endif /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
-    {
-        /* Provide a stub for this function. */
-        return eDHCPContinue;
-    }
-
-#endif /* if ( ( ipconfigUSE_TCP == 1 ) && ( ipconfigUSE_DHCP_HOOK != 0 ) ) */
+#endif /* ipconfigUSE_TCP */
 /*-----------------------------------------------------------*/

FreeRTOS-Plus/Demo/FreeRTOS_Plus_TCP_Echo_Qemu_mps2/TCPEchoClient_SingleTasks.c

@@ -395,4 +395,22 @@
         return xReturn;
     }
 
+
+    #if ( ipconfigUSE_DHCP_HOOK != 0 )
+
+        #if ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 )
+            eDHCPCallbackAnswer_t xApplicationDHCPHook( eDHCPCallbackPhase_t eDHCPPhase,
+                                                        uint32_t ulIPAddress )
+        #else /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
+            eDHCPCallbackAnswer_t xApplicationDHCPHook_Multi( eDHCPCallbackPhase_t eDHCPPhase,
+                                                              struct xNetworkEndPoint * pxEndPoint,
+                                                              IP_Address_t * pxIPAddress )
+        #endif /* ( ipconfigIPv4_BACKWARD_COMPATIBLE == 1 ) */
+        {
+            /* Provide a stub for this function. */
+            return eDHCPContinue;
+        }
+
+    #endif /* if ( ipconfigUSE_DHCP_HOOK != 0 )*/
+
 #endif /* ipconfigUSE_TCP */

FreeRTOS-Plus/Demo/FreeRTOS_Plus_TCP_Echo_Qemu_mps2/main_networking.c

@@ -164,6 +164,8 @@ void main_tcp_echo_client_tasks( void )
 
     #if defined( ipconfigIPv4_BACKWARD_COMPATIBLE ) && ( ipconfigIPv4_BACKWARD_COMPATIBLE == 0 )
         /* Initialise the interface descriptor for WinPCap. */
+        extern NetworkInterface_t * pxMPS2_FillInterfaceDescriptor( BaseType_t xEMACIndex,
+                                                                    NetworkInterface_t * pxInterface );
         pxMPS2_FillInterfaceDescriptor( 0, &( xInterfaces[ 0 ] ) );
 
         /* === End-point 0 === */