mailchimp extension error, php 7.1, civi 5.10.4, drupal 7.x
patch:

index 5b82f65e..76c816dc 100644
--- a/uk.co.vedaconsulting.mailchimp-2.0.1/CRM/Mailchimp/Permission.php
+++ b/uk.co.vedaconsulting.mailchimp-2.0.1/CRM/Mailchimp/Permission.php
@@ -1,6 +1,6 @@
 &lt;?php

-class CRM_Mailchimp_Permission extends CRM_Core_Permission {
+class CRM_Mailchimp_Permission {

   /**
    * Returns an array of permissions defined by this extension. Modeled off of
@@ -35,6 +35,6 @@ class CRM_Mailchimp_Permission extends CRM_Core_Permission {
         }
       });
     }
-    return parent::check($permissions);
+    return CRM_Core_Permission::check($permissions,NULL);
   }
 }