Minor perf improvement to clr.async.task/result and clr.async.task/task-result.

Author: dmiller

Clojure/Clojure.Source/clojure/clr/async/task.clj

@@ -4,23 +4,29 @@
   (:refer-clojure :exclude [await])
   (:import [System.Threading.Tasks Task]))
 
-(set! *warn-on-reflection* true)
 
 ;; ── Internal helpers ──────────────────────────────────────────────────
 
+; This would get a reflection warning, so we don't turn on *warn-on-reflection* until after.
+; We WANT a reflection warning -- we need the DLR callsite mechanism on the call to .GetAwaiter.
+; If we tag the task parameter as ^Task, we always pick up Task.GetAwaiter(), even for generic Task<TResult> tasks.
+; That just does not work.
+
 (defn- task-result
   "Extracts the result from a completed Task<T> via its typed awaiter.
    Uses GetAwaiter().GetResult() which unwraps exceptions cleanly
    (no AggregateException wrapping unlike .Result).
    Returns nil for non-generic Task (void)."
-  [^Task task]
-  (let [t (.GetType task)]
+ [task]
+  (let [t (.GetType ^Object task)]
     (when (.IsGenericType t)
       (let [^Type type-arg (aget (.GetGenericArguments t) 0)]
         (when-not (= "VoidTaskResult" (.Name type-arg))
-          (let [awaiter (.Invoke (.GetMethod t "GetAwaiter" Type/EmptyTypes) task nil)]
-            (.Invoke (.GetMethod (.GetType ^Object awaiter) "GetResult" Type/EmptyTypes)
-                     awaiter nil)))))))
+		    (-> task .GetAwaiter .GetResult))))))	
+
+
+(set! *warn-on-reflection* true)
+
 
 ;; ── Macros (only these two require macro status) ──────────────────────
 
@@ -127,9 +133,5 @@
      (t/result (t/->task 42))       ;=> 42
      (t/result (t/completed-task))   ;=> nil
      (t/result (t/async (t/await (t/delay-task 100)) \"done\"))  ;=> \"done\""
-  [^Task task]
-  ;; Block until complete. Non-generic GetResult() handles void tasks
-  ;; and throws inner exception (not AggregateException) on fault.
-  (-> task .GetAwaiter .GetResult)
-  ;; For Task<T>, extract the typed result via the generic awaiter.
+  [task]
   (task-result task))