refactor(eval): get rid of OnFinish type alias b/c of bad naming (#424)

monix-eval/shared/src/main/scala/monix/eval/Task.scala

@@ -1255,13 +1255,13 @@ object Task extends TaskInstances {
     *    execution (e.g. `asyncOnSuccess` and `asyncOnError`)
     *
     * **WARNING:** note that not only is this builder unsafe, but also
-    * unstable, as the [[OnFinish]] callback type is exposing volatile
-    * internal implementation details. This builder is meant to create
+    * unstable, as the callback type is exposing volatile internal
+    * implementation details. This builder is meant to create
     * optimized asynchronous tasks, but for normal usage prefer
     * [[Task.create]].
     */
-  def unsafeCreate[A](onFinish: OnFinish[A]): Task[A] =
-    Async(onFinish)
+  def unsafeCreate[A](register: (Context, Callback[A]) => Unit): Task[A] =
+    Async(register)
 
   /** Converts the given Scala `Future` into a `Task`.
     *
@@ -1506,11 +1506,6 @@ object Task extends TaskInstances {
     */
   type FrameIndex = Int
 
-  /** Type alias representing callbacks for
-    * [[unsafeCreate asynchronous]] tasks.
-    */
-  type OnFinish[+A] = (Context, Callback[A]) => Unit
-
   /** Set of options for customizing the task's behavior.
     *
     * @param autoCancelableRunLoops should be set to `true` in
@@ -1754,9 +1749,12 @@ object Task extends TaskInstances {
     * Unsafe to build directly, only use if you know what you're doing.
     * For building `Async` instances safely, see [[create]].
     */
-  private[eval] final case class Async[+A](onFinish: OnFinish[A]) extends Task[A] {
+  private[eval] final case class Async[+A](
+    register: (Context, Callback[A]) => Unit)
+    extends Task[A] {
+
     override def toString: String =
-      s"Task.Async($onFinish)"
+      s"Task.Async($register)"
   }
 
   /** Internal [[Task]] state that defers the evaluation of the

monix-eval/shared/src/main/scala/monix/eval/internal/TaskRunLoop.scala

@@ -17,7 +17,7 @@
 
 package monix.eval.internal
 
-import monix.eval.Task.{Async, Context, Error, Eval, FlatMap, FrameIndex, MemoizeSuspend, Now, OnFinish, Suspend, fromTry}
+import monix.eval.Task.{Async, Context, Error, Eval, FlatMap, FrameIndex, MemoizeSuspend, Now, Suspend, fromTry}
 import monix.eval.{Callback, Task}
 import monix.execution.atomic.AtomicAny
 import monix.execution.cancelables.StackedCancelable
@@ -145,7 +145,7 @@ private[eval] object TaskRunLoop {
       rcb: RestartCallback,
       bFirst: Bind,
       bRest: CallStack,
-      onFinish: OnFinish[Any],
+      register: (Context, Callback[Any]) => Unit,
       nextFrame: FrameIndex): Unit = {
 
       if (!context.shouldCancel) {
@@ -163,7 +163,7 @@ private[eval] object TaskRunLoop {
         // rcb reference might be null, so initializing
         val restartCallback = if (rcb != null) rcb else new RestartCallback(context, cb)
         restartCallback.prepare(bFirst, bRest)
-        onFinish(context, restartCallback)
+        register(context, restartCallback)
       }
     }
 

project/MimaFilters.scala

@@ -154,7 +154,8 @@ object MimaFilters {
     exclude[MissingTypesProblem]("monix.eval.Coeval$Error"),
     exclude[MissingTypesProblem]("monix.eval.Coeval$Now"),
     exclude[ReversedAbstractMethodProblem]("monix.eval.internal.Transformation.apply"),
-    exclude[ReversedMissingMethodProblem]("monix.eval.TaskInstances.catsInstances")
+    exclude[ReversedMissingMethodProblem]("monix.eval.TaskInstances.catsInstances"),
+    exclude[DirectMissingMethodProblem]("monix.eval.Task#Async.onFinish")
   )
 
   /** `monix-react` 3.0.0 */