Imported Upstream snapshot 8.3~beta0+13298

1 files changed, 25 insertions, 0 deletions

diff --git a/test-suite/failure/universes3.v b/test-suite/failure/universes3.v
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+(* This example (found by coqchk) checks that an inductive cannot be
+   polymorphic if its constructors induce upper universe constraints.
+   Here: I cannot be polymorphic because its type is less than the
+   type of the argument of impl. *)
+
+Definition Type1 := Type.
+Definition Type3 : Type1 := Type.                       (* Type3 < Type1 *)
+Definition Type4 := Type.
+Definition impl (A B:Type3) : Type4 := A->B.           (* Type3 <= Type4 *)
+Inductive I (B:Type (*6*)) := C : B -> impl Prop (I B).
+    (* Type(6) <= Type(7)     because I contains, via C, elements in B
+       Type(7) <=  Type3      because (I B) is argument of impl
+       Type(4) <=  Type(7)    because type of C less than I (see remark below)
+
+       where Type(7) is the auxiliary level used to infer the type of I
+*)
+
+(* We cannot enforce Type1 < Type(6) while we already have
+   Type(6) <= Type(7) < Type3 < Type1 *)
+Definition J := I Type1.
+
+(* Open question: should the type of an inductive be the max of the
+   types of the _arguments_ of its constructors (here B and Prop,
+   after unfolding of impl), or of the max of types of the
+   constructors itself (here B -> impl Prop (I B)), as done above. *)