fixes #6631

tests/array/troof1.nim

@@ -1,6 +1,10 @@
 discard """
   output: '''@[2, 3, 4]321
-9.0 4.0'''
+9.0 4.0
+3
+@[(Field0: 1, Field1: 2), (Field0: 3, Field1: 5)]
+2
+@[a, new one, c]'''
 """
 
 proc foo[T](x, y: T): T = x
@@ -11,3 +15,23 @@ echo a[1.. ^1], a[^2], a[^3], a[^4]
 echo b[^1][^1], " ", (b[^2]).foo(b[^1])[^1]
 
 b[^1] = [8.8, 8.9]
+
+var c: seq[(int, int)] = @[(1,2), (3,4)]
+
+proc takeA(x: ptr int) = echo x[]
+
+takeA(addr c[^1][0])
+c[^1][1] = 5
+echo c
+
+proc useOpenarray(x: openArray[int]) =
+  echo x[^2]
+
+proc mutOpenarray(x: var openArray[string]) =
+  x[^2] = "new one"
+
+useOpenarray([1, 2, 3])
+
+var z = @["a", "b", "c"]
+mutOpenarray(z)
+echo z