fixes #1838

tests/iter/timplicit_auto.nim

@@ -0,0 +1,18 @@
+# bug #1838
+
+type State = enum Empty, Tree, Fire
+
+const
+  disp: array[State, string] = ["  ", "\e[32m/\\\e[m", "\e[07;31m/\\\e[m"]
+
+proc univ(x, y: int): State = Tree
+
+var w, h = 30
+
+iterator fields(a = (0,0), b = (h-1,w-1)) =
+  for y in max(a[0], 0) .. min(b[0], h-1):
+    for x in max(a[1], 0) .. min(b[1], w-1):
+      yield (y,x)
+
+for y,x in fields():
+  stdout.write disp[univ(x, y)]