Fixing first part of bug #3210 (inference of pattern-matching return

clause in the presence of let-ins in the arity of inductive type).

3 files changed, 41 insertions, 7 deletions

diff --git a/pretyping/cases.ml b/pretyping/cases.ml
index 7c3165fa8e..fcbe90b6a7 100644
--- a/pretyping/cases.ml
+++ b/pretyping/cases.ml
@@ -285,11 +285,13 @@ let inductive_template evdref env tmloc ind =
    applist (mkIndU indu,List.rev evarl)
 
 let try_find_ind env sigma typ realnames =
-  let (IndType(_,realargs) as ind) = find_rectype env sigma typ in
+  let (IndType(indf,realargs) as ind) = find_rectype env sigma typ in
   let names =
     match realnames with
       | Some names -> names
-      | None -> List.make (List.length realargs) Anonymous in
+      | None ->
+          let ind = fst (fst (dest_ind_family indf)) in
+          List.make (inductive_nrealdecls ind) Anonymous in
   IsInd (typ,ind,names)
 
 let inh_coerce_to_ind evdref env loc ty tyi =
@@ -730,7 +732,17 @@ let set_declaration_name x (_,c,t) = (x,c,t)
 
 let recover_initial_subpattern_names = List.map2 set_declaration_name
 
-let recover_alias_names get_name = List.map2 (fun x (_,c,t) ->(get_name x,c,t))
+let recover_and_adjust_alias_names names sign =
+  let rec aux = function
+  | [],[] ->
+      []
+  | x::names, (_,None,t)::sign ->
+      (x,(alias_of_pat x,None,t)) :: aux (names,sign)
+  | names, (na,(Some _ as c),t)::sign ->
+      (PatVar (Loc.ghost,na),(na,c,t)) :: aux (names,sign)
+  | _ -> assert false
+  in
+  List.split (aux (names,sign))
 
 let push_rels_eqn sign eqn =
   {eqn with
@@ -1695,11 +1707,12 @@ let build_inversion_problem loc env sigma tms t =
 	let pat,acc = make_patvar t acc in
 	let indf' = lift_inductive_family n indf in
 	let sign = make_arity_signature env true indf' in
-	let sign = recover_alias_names alias_of_pat (pat :: List.rev patl) sign in
-	let p = List.length realargs in
+        let patl = pat :: List.rev patl in
+	let patl,sign = recover_and_adjust_alias_names patl sign in
+	let p = List.length patl in
 	let env' = push_rel_context sign env in
-	let patl',acc_sign,acc = aux (n+p+1) env' (sign@acc_sign) tms acc in
-	patl@pat::patl',acc_sign,acc
+	let patl',acc_sign,acc = aux (n+p) env' (sign@acc_sign) tms acc in
+	List.rev_append patl patl',acc_sign,acc
     | (t, NotInd (bo,typ)) :: tms ->
       let pat,acc = make_patvar t acc in
       let d = (alias_of_pat pat,None,typ) in
diff --git a/test-suite/bugs/closed/3210.v b/test-suite/bugs/closed/3210.v
new file mode 100644
index 0000000000..e66bf922d7
--- /dev/null
+++ b/test-suite/bugs/closed/3210.v
@@ -0,0 +1,9 @@
+(* Test support of let-in in arity of inductive types *)
+
+Inductive Foo : let X := Set in X :=
+| I : Foo.
+
+Definition foo (x : Foo) : bool :=
+  match x with
+  I => true
+  end.
diff --git a/test-suite/success/Case22.v b/test-suite/success/Case22.v
index 4eb2dbe9f5..ce9050d421 100644
--- a/test-suite/success/Case22.v
+++ b/test-suite/success/Case22.v
@@ -5,3 +5,15 @@ Lemma a : forall x:I eq_refl, match x in I a b c return b = b with C => eq_refl
 intro.
 match goal with |- ?c => let x := eval cbv in c in change x end.
 Abort.
+
+Check forall x:I eq_refl, match x in I x return x = x with C => eq_refl end = eq_refl.
+
+(* This is bug #3210 *)
+
+Inductive I' : let X := Set in X :=
+| C' : I'.
+
+Definition foo (x : I') : bool :=
+  match x with
+  C' => true
+  end.