Fixing critical inductive polymorphism bug found by Bruno.

If two distinct parameters of the inductive type contributes to
polymorphism, they must have distinct names, othewise an aliasing
problem of the form "fun x x => max(x,x)" happens.

Also insisted that a parameter contributes to universe polymorphism
only if the corresponding occurrence of Type is not hidden behind a
definition.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@14511 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 15 insertions, 0 deletions

diff --git a/test-suite/failure/inductive4.v b/test-suite/failure/inductive4.v
new file mode 100644
index 000000000..6ba36fd20
--- /dev/null
+++ b/test-suite/failure/inductive4.v
@@ -0,0 +1,15 @@
+(* This used to succeed in versions 8.1 to 8.3 *)
+
+Require Import Logic.
+Require Hurkens.
+Definition Ti := Type.
+Inductive prod (X Y:Ti) := pair : X -> Y -> prod X Y.
+Definition B : Prop := let F := prod True in F Prop. (* Aie! *)
+Definition p2b (P:Prop) : B := pair True Prop I P.
+Definition b2p (b:B) : Prop := match b with pair _ P => P end.
+Lemma L1 : forall A : Prop, b2p (p2b A) -> A.
+Proof (fun A x => x).
+Lemma L2 : forall A : Prop, A -> b2p (p2b A).
+Proof (fun A x => x).
+Check Hurkens.paradox B p2b b2p L1 L2.
+