fixes #13519

lib/pure/asyncdispatch.nim

@@ -278,7 +278,7 @@ when defined(windows) or defined(nimdoc):
     result.ioPort = createIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0, 1)
     result.handles = initSet[AsyncFD]()
     result.timers.newHeapQueue()
-    result.callbacks = initDeque[proc ()](64)
+    result.callbacks = initDeque[proc () {.closure, gcsafe.}](64)
 
   var gDisp{.threadvar.}: owned PDispatcher ## Global dispatcher
 

lib/pure/asyncmacro.nim

@@ -46,7 +46,7 @@ template createCb(retFutureSym, iteratorNameSym,
         else:
           {.gcsafe.}:
             {.push hint[ConvFromXtoItselfNotNeeded]: off.}
-            next.callback = (proc() {.closure, gcsafe.})(identName)
+            next.callback = cast[proc() {.closure, gcsafe.}](identName)
             {.pop.}
     except:
       futureVarCompletions