Yield in try

tests/async/tasynctry2.nim

@@ -1,10 +1,12 @@
 discard """
   file: "tasynctry2.nim"
   errormsg: "\'yield\' cannot be used within \'try\' in a non-inlined iterator"
-  line: 15
+  line: 17
 """
 import asyncdispatch
 
+{.experimental: "oldIterTransf".}
+
 proc foo(): Future[bool] {.async.} = discard
 
 proc test5(): Future[int] {.async.} =

tests/iter/tyieldintry.nim

@@ -0,0 +1,201 @@
+discard """
+targets: "c cpp"
+output: "ok"
+"""
+var closureIterResult = newSeq[int]()
+
+proc checkpoint(arg: int) =
+    closureIterResult.add(arg)
+
+type
+    TestException = object of Exception
+    AnotherException = object of Exception
+
+proc testClosureIterAux(it: iterator(): int, exceptionExpected: bool, expectedResults: varargs[int]) =
+    closureIterResult.setLen(0)
+
+    var exceptionCaught = false
+
+    try:
+        for i in it():
+            closureIterResult.add(i)
+    except TestException:
+        exceptionCaught = true
+
+    if closureIterResult != @expectedResults or exceptionCaught != exceptionExpected:
+        if closureIterResult != @expectedResults:
+            echo "Expected: ", @expectedResults
+            echo "Actual: ", closureIterResult
+        if exceptionCaught != exceptionExpected:
+            echo "Expected exception: ", exceptionExpected
+            echo "Got exception: ", exceptionCaught
+        doAssert(false)
+
+proc test(it: iterator(): int, expectedResults: varargs[int]) =
+    testClosureIterAux(it, false, expectedResults)
+
+proc testExc(it: iterator(): int, expectedResults: varargs[int]) =
+    testClosureIterAux(it, true, expectedResults)
+
+proc raiseException() =
+    raise newException(TestException, "Test exception!")
+
+block:
+    iterator it(): int {.closure.} =
+        var i = 5
+        while i != 0:
+            yield i
+            if i == 3:
+                yield 123
+            dec i
+
+    test(it, 5, 4, 3, 123, 2, 1)
+
+block:
+    iterator it(): int {.closure.} =
+        yield 0
+        try:
+            checkpoint(1)
+            raiseException()
+        except TestException:
+            checkpoint(2)
+            yield 3
+            checkpoint(4)
+        finally:
+            checkpoint(5)
+
+        checkpoint(6)
+
+    test(it, 0, 1, 2, 3, 4, 5, 6)
+
+block:
+    iterator it(): int {.closure.} =
+        yield 0
+        try:
+            yield 1
+            checkpoint(2)
+        finally:
+            checkpoint(3)
+            yield 4
+            checkpoint(5)
+            yield 6
+
+    test(it, 0, 1, 2, 3, 4, 5, 6)
+
+block:
+    iterator it(): int {.closure.} =
+        yield 0
+        try:
+            yield 1
+            raiseException()
+            yield 2
+        finally:
+            checkpoint(3)
+            yield 4
+            checkpoint(5)
+            yield 6
+
+    testExc(it, 0, 1, 3, 4, 5, 6)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            try:
+                raiseException()
+            except AnotherException:
+                yield 123
+            finally:
+                checkpoint(3)
+        finally:
+            checkpoint(4)
+
+    testExc(it, 3, 4)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            yield 1
+            raiseException()
+        except AnotherException:
+            checkpoint(123)
+        finally:
+            checkpoint(2)
+        checkpoint(3)
+
+    testExc(it, 1, 2)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            yield 0
+            try:
+                yield 1
+                try:
+                    yield 2
+                    raiseException()
+                except AnotherException:
+                    yield 123
+                finally:
+                    yield 3
+            except AnotherException:
+                yield 124
+            finally:
+                yield 4
+            checkpoint(1234)
+        except:
+            yield 5
+            checkpoint(6)
+        finally:
+            checkpoint(7)
+            yield 8
+        checkpoint(9)
+
+    test(it, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            yield 0
+            return 2
+        finally:
+            checkpoint(1)
+        checkpoint(123)
+
+    test(it, 0, 1)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            try:
+                yield 0
+                raiseException()
+            finally:
+                checkpoint(1)
+        except TestException:
+            yield 2
+            return
+        finally:
+            yield 3
+
+        checkpoint(123)
+
+    test(it, 0, 1, 2, 3)
+
+block:
+    iterator it(): int {.closure.} =
+        try:
+            try:
+                yield 0
+                raiseException()
+            finally:
+                return # Return in finally should stop exception propagation
+        except AnotherException:
+            yield 2
+            return
+        finally:
+            yield 3
+        checkpoint(123)
+
+    test(it, 0, 3)
+
+echo "ok"