Fix `or` deadlock issue. (#517)

* Fix `or` should not create future with OwnCancelSchedule flag set.

* Fix `CancelledError` missing from raises list when both futures has empty raises list.

* Fix macros tests.

chronos/internal/asyncfutures.nim

@@ -786,7 +786,7 @@ template orImpl*[T, Y](fut1: Future[T], fut2: Future[Y]): untyped =
   fut2.addCallback(cb)
 
   retFuture.cancelCallback = cancellation
-  return retFuture
+  retFuture
 
 proc `or`*[T, Y](fut1: Future[T], fut2: Future[Y]): Future[void] =
   ## Returns a future which will complete once either ``fut1`` or ``fut2``
@@ -801,7 +801,7 @@ proc `or`*[T, Y](fut1: Future[T], fut2: Future[Y]): Future[void] =
   ## completed, the result future will also be completed.
   ##
   ## If cancelled, ``fut1`` and ``fut2`` futures WILL NOT BE cancelled.
-  var retFuture = newFuture[void]("chronos.or")
+  var retFuture = newFuture[void]("chronos.or()")
   orImpl(fut1, fut2)
 
 
@@ -1665,10 +1665,9 @@ proc `or`*[T, Y, E1, E2](
     fut1: InternalRaisesFuture[T, E1],
     fut2: InternalRaisesFuture[Y, E2]): auto =
   type
-    InternalRaisesFutureRaises = union(E1, E2)
+    InternalRaisesFutureRaises = union(E1, E2).union((CancelledError,))
 
-  let
-    retFuture = newFuture[void]("chronos.wait()", {FutureFlag.OwnCancelSchedule})
+  let retFuture = newFuture[void]("chronos.or()", {})
   orImpl(fut1, fut2)
 
 proc wait*(fut: InternalRaisesFuture, timeout = InfiniteDuration): auto =

tests/testbugs.nim

@@ -135,6 +135,16 @@ suite "Asynchronous issues test suite":
     await server.closeWait()
     return true
 
+  proc testOrDeadlock(): Future[bool] {.async.} =
+    proc f(): Future[void] {.async.} =
+      await sleepAsync(2.seconds) or sleepAsync(1.seconds)
+    let fx = f()
+    try:
+      await fx.cancelAndWait().wait(2.seconds)
+    except AsyncTimeoutError:
+      return false
+    true
+
   test "Issue #6":
     check waitFor(issue6()) == true
 
@@ -152,3 +162,6 @@ suite "Asynchronous issues test suite":
 
   test "IndexError crash test":
     check waitFor(testIndexError()) == true
+
+  test "`or` deadlock [#516] test":
+    check waitFor(testOrDeadlock()) == true

tests/testmacro.nim

@@ -491,7 +491,7 @@ suite "Exceptions tracking":
     proc testit2 {.async: (raises: [IOError]).} =
       raise (ref IOError)()
 
-    proc test {.async: (raises: [ValueError, IOError]).} =
+    proc test {.async: (raises: [CancelledError, ValueError, IOError]).} =
       await testit() or testit2()
 
     proc noraises() {.raises: [].} =