test(tests/lean/run): workaround for issue #505

tests/lean/run/505.lean

@@ -0,0 +1,20 @@
+import data.set
+open set
+
+section
+  variable {A : Type}
+
+  definition set_of (P : A → Prop) : set A := P
+
+  notation `{` binders `|` r:(scoped:1 P, set_of P) `}` := r
+
+  definition insert (a : A) (s : set A) : set A := {x : A | x = a ∨ x ∈ s}
+
+  notation `⦃` s:(foldr `,` (a t, insert a t) ∅) `⦄` := s
+  notation `{` `{` s:(foldr `,` (a t, insert a t) ∅) `}` `}` := s
+
+  check ⦃1, 2, 3⦄
+  check {{1, 2, 3}}
+
+  definition foo  {X : Type} {{ x : X }} : X := x
+end