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diff --git a/Test/triggers/old-is-a-special-case-for-triggers.dfy b/Test/triggers/old-is-a-special-case-for-triggers.dfy
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+++ b/Test/triggers/old-is-a-special-case-for-triggers.dfy
@@ -0,0 +1,32 @@
+// RUN: %dafny /compile:0 /print:"%t.print" /dprint:"%t.dprint" /autoTriggers:1 /printTooltips "%s" > "%t"
+// RUN: %diff "%s.expect" "%t"
+
+// This file ensures that `old()` receives the special treatment that it
+// requires; that is, `old(f(x))` is not less liberal than `f(x)`, and
+// old(f(f(x))) does not loop with f(x) (doesn't it?)
+
+class C { }
+function f(c: C): C
+function g(c: C): C
+function h(c: C, i: int): C
+
+method M(sc: set<C>)
+  // Ensure that old(c) does not get picked as a trigger
+  ensures forall c | c in sc :: true || c == old(f(c))
+
+  // This checks whether loop detection handles `old` expressions properly.
+  // In the first one f(c)/old(f(f(c))) is not reported as a loop. See
+  // looping-is-hard-to-decide-modulo-equalities.dfy for an explanation.
+  ensures forall c | c in sc :: true || f(c) == old(f(f(c)))
+  ensures forall c | c in sc :: true || old(f(f(c))) == old(g(f(c))) || old(f(g(c))) == g(f(c)) || f(g(c)) == g(f(c))
+
+  // These check that the final trigger filtering step doesn't get confused
+  // between old expressions and regular expressions.
+  ensures forall c | c in sc :: true || f(c) == old(g(f(c)))
+  ensures forall c | c in sc :: true || f(c) == old(f(c)) || old(g(f(c))) == g(f(c))
+
+  // WISH: A Dafny rewriter could cleanup expressions so that adding the
+  //       expression forall c :: c == old(c) in a quantifier would cause a warning,
+  //       instead of a trigger generation error as it does now.
+{
+}