[core] Make ActorRef methods const

So that the lambdas calling these methods do not have to be mutable.

1 files changed, 2 insertions, 2 deletions

diff --git a/include/mbgl/actor/actor_ref.hpp b/include/mbgl/actor/actor_ref.hpp
index 958ee3777c..d700a86d1a 100644
--- a/include/mbgl/actor/actor_ref.hpp
+++ b/include/mbgl/actor/actor_ref.hpp
@@ -29,14 +29,14 @@ public:
     }
 
     template <typename Fn, class... Args>
-    void invoke(Fn fn, Args&&... args) {
+    void invoke(Fn fn, Args&&... args) const {
         if (auto mailbox = weakMailbox.lock()) {
             mailbox->push(actor::makeMessage(*object, fn, std::forward<Args>(args)...));
         }
     }
 
     template <typename Fn, class... Args>
-    auto ask(Fn fn, Args&&... args) {
+    auto ask(Fn fn, Args&&... args) const {
         // Result type is deduced from the function's return type
         using ResultType = typename std::result_of<decltype(fn)(Object, Args...)>::type;