closes #11042; add testcase (#19935)

close #11042; add testcase

tests/closure/t11042.nim

@@ -0,0 +1,55 @@
+discard """
+  output:'''
+foo: 1
+foo: 2
+bar: 1
+bar: 2
+foo: 1
+foo: 2
+bar: 1
+bar: 2
+bar: 3
+bar: 4
+bar: 5
+bar: 6
+bar: 7
+bar: 8
+bar: 9
+'''
+"""
+
+# bug #11042
+block:
+  iterator foo: int =
+    for x in 1..2:
+      echo "foo: ", x
+      for y in 1..2:
+        discard
+
+  for x in foo(): discard
+
+  let bar = iterator: int =
+    for x in 1..2:
+      echo "bar: ", x
+      for y in 1..2:
+        discard
+
+  for x in bar(): discard
+
+
+block:
+  iterator foo: int =
+    for x in 1..2:
+      echo "foo: ", x
+      for y in 1..2:
+        discard
+
+  for x in foo(): discard
+
+  let bar = iterator: int =
+    for x in 1..9:
+      echo "bar: ", x
+      for y in 1..2:
+        discard
+
+  for x in bar(): discard