From 2c59d19ad207a6bf193e9f0c9d73258b3133d484 Mon Sep 17 00:00:00 2001
From: Matthieu Sozeau
Date: Thu, 9 Jul 2015 16:58:06 +0200
Subject: Kernel/Checker: Cleanup fixes of substitutions due to let-ins.

Avoid undeeded large substitutions, and add test-suite file for
fixed bug 4283 in closed/
---
 checker/inductive.ml          |  7 ++-----
 kernel/inductive.ml           | 11 +++++------
 test-suite/bugs/closed/4283.v |  8 ++++++++
 3 files changed, 15 insertions(+), 11 deletions(-)
 create mode 100644 test-suite/bugs/closed/4283.v

diff --git a/checker/inductive.ml b/checker/inductive.ml
index 5d31649737..e3d8dd2060 100644
--- a/checker/inductive.ml
+++ b/checker/inductive.ml
@@ -104,14 +104,11 @@ let instantiate_params full t u args sign =
 let full_inductive_instantiate mib u params sign =
   let dummy = Prop Null in
   let t = mkArity (sign,dummy) in
-  let ar = fst (destArity (instantiate_params true t u params mib.mind_params_ctxt)) in
-    subst_instance_context u ar
-
+    fst (destArity (instantiate_params true t u params mib.mind_params_ctxt))
 
 let full_constructor_instantiate ((mind,_),u,(mib,_),params) t =
   let inst_ind = constructor_instantiate mind u mib t in
-    instantiate_params true inst_ind u params
-		       (subst_instance_context u mib.mind_params_ctxt)
+    instantiate_params true inst_ind u params mib.mind_params_ctxt
 
 (************************************************************************)
 (************************************************************************)
diff --git a/kernel/inductive.ml b/kernel/inductive.ml
index 84084718f0..00d14a25e2 100644
--- a/kernel/inductive.ml
+++ b/kernel/inductive.ml
@@ -73,7 +73,7 @@ let constructor_instantiate mind u mib c =
   let s = ind_subst mind mib u in
     substl s (subst_instance_constr u c)
 
-let instantiate_params full t args sign =
+let instantiate_params full t u args sign =
   let fail () =
     anomaly ~label:"instantiate_params" (Pp.str "type, ctxt and args mismatch") in
   let (rem_args, subs, ty) =
@@ -81,7 +81,8 @@ let instantiate_params full t args sign =
       (fun (_,copt,_) (largs,subs,ty) ->
         match (copt, largs, kind_of_term ty) with
           | (None, a::args, Prod(_,_,t)) -> (args, a::subs, t)
-          | (Some b,_,LetIn(_,_,_,t))    -> (largs, (substl subs b)::subs, t)
+          | (Some b,_,LetIn(_,_,_,t))    ->
+	     (largs, (substl subs (subst_instance_constr u b))::subs, t)
 	  | (_,[],_)                -> if full then fail() else ([], subs, ty)
 	  | _                       -> fail ())
       sign
@@ -93,13 +94,11 @@ let instantiate_params full t args sign =
 let full_inductive_instantiate mib u params sign =
   let dummy = prop_sort in
   let t = mkArity (sign,dummy) in
-  let ar = fst (destArity (instantiate_params true t params mib.mind_params_ctxt)) in
-    Vars.subst_instance_context u ar
+    fst (destArity (instantiate_params true t u params mib.mind_params_ctxt))
 
 let full_constructor_instantiate ((mind,_),u,(mib,_),params) t =
   let inst_ind = constructor_instantiate mind u mib t in
-   instantiate_params true inst_ind params
-		      (Vars.subst_instance_context u mib.mind_params_ctxt)
+   instantiate_params true inst_ind u params mib.mind_params_ctxt
 		      
 (************************************************************************)
 (************************************************************************)
diff --git a/test-suite/bugs/closed/4283.v b/test-suite/bugs/closed/4283.v
new file mode 100644
index 0000000000..e06998b711
--- /dev/null
+++ b/test-suite/bugs/closed/4283.v
@@ -0,0 +1,8 @@
+Require Import Hurkens.
+
+Polymorphic Record box (X : Type) (T := Type) : Type := wrap { unwrap : T }.
+
+Definition unwrap' := fun (X : Type) (b : box X) => let (unwrap) := b in unwrap.
+
+Fail Definition bad : False := TypeNeqSmallType.paradox (unwrap' Type (wrap _ Type)) eq_refl.
+
-- 
cgit v1.2.3