1 files changed, 35 insertions, 0 deletions
diff --git a/tests/effects/tfuncs_cannot_mutate.nim b/tests/effects/tfuncs_cannot_mutate.nim
new file mode 100644
index 000000000..9934d27a7
--- /dev/null
+++ b/tests/effects/tfuncs_cannot_mutate.nim
@@ -0,0 +1,35 @@
+discard """
+  errormsg: "cannot mutate location select(x, z).data within a strict func"
+  line: 35
+"""
+
+{.experimental: "strictFuncs".}
+
+type
+  Node = ref object
+    le, ri: Node
+    data: string
+
+func insert(x: var seq[Node]; yyy: Node) =
+  let L = x.len
+  x.setLen L + 1
+  x[L] = yyy
+
+func len(n: Node): int =
+  var it = n
+  while it != nil:
+    inc result
+    it = it.ri
+
+func doNotDistract(n: Node) =
+  var m = Node(data: "abc")
+
+func select(a, b: Node): Node = b
+
+func mutate(n: Node) =
+  var it = n
+  let x = it
+  let y = x
+  let z = y
+
+  select(x, z).data = "tricky"