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Diffstat (limited to 'test-suite/failure/universes3.v')
| -rw-r--r-- | test-suite/failure/universes3.v | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/test-suite/failure/universes3.v b/test-suite/failure/universes3.v new file mode 100644 index 00000000..8fb414d5 --- /dev/null +++ b/test-suite/failure/universes3.v @@ -0,0 +1,25 @@ +(* 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. *) |