2 files changed, 75 insertions, 6 deletions
diff --git a/kernel/modops.ml b/kernel/modops.ml
index c194a6c71..7459dcad8 100644
--- a/kernel/modops.ml
+++ b/kernel/modops.ml
@@ -184,12 +184,17 @@ and add_module mp mb env =
       | MTBfunsig _ -> env
 
 
-let strengthen_const env mp l cb = match cb.const_body with
-  | Some _ -> cb
-  | None -> {cb with const_body = 
-	       let const = mkConst (make_kn mp empty_dirpath l) in 
-		 Some (Declarations.from_val const)
-	    }
+let strengthen_const env mp l cb = 
+  match cb.const_opaque, cb.const_body with
+  | false, Some _ -> cb
+  | true, Some _ 
+  | _, None -> 
+      let const = mkConst (make_kn mp empty_dirpath l) in 
+      let const_subs = Some (Declarations.from_val const) in
+	{cb with 
+      	   const_body = const_subs;
+	   const_opaque = false
+	}
 
 let strengthen_mind env mp l mib = match mib.mind_equiv with
   | Some _ -> mib
diff --git a/test-suite/success/Mod_strengthen.v b/test-suite/success/Mod_strengthen.v
new file mode 100644
index 000000000..a472e698f
--- /dev/null
+++ b/test-suite/success/Mod_strengthen.v
@@ -0,0 +1,64 @@
+Module Type Sub.
+  Axiom Refl1 : (x:nat)(x=x).
+  Axiom Refl2 : (x:nat)(x=x).
+  Axiom Refl3 : (x:nat)(x=x).
+  Inductive T : Set := A : T.
+End Sub.
+
+Module Type Main.
+  Declare Module M:Sub.
+End Main.
+
+
+Module A <: Main.
+  Module M <: Sub.
+    Lemma Refl1 : (x:nat) x=x.
+      Intros;Reflexivity.
+    Qed.
+    Axiom Refl2 : (x:nat) x=x.
+    Lemma Refl3 : (x:nat) x=x.
+      Intros;Reflexivity.
+    Defined.
+    Inductive T : Set := A : T.
+  End M.
+End A.
+
+
+
+(* first test *)
+
+Module F[S:Sub].
+  Module M:=S.
+End F.
+
+Module B <: Main with Module M:=A.M := F A.M.
+
+
+
+(* second test *)
+
+Lemma r1 : (A.M.Refl1 == B.M.Refl1).
+Proof.
+  Reflexivity.
+Qed.
+
+Lemma r2 : (A.M.Refl2 == B.M.Refl2).
+Proof.
+  Reflexivity.
+Qed.
+
+Lemma r3 : (A.M.Refl3 == B.M.Refl3).
+Proof.
+  Reflexivity.
+Qed.
+
+Lemma t : (A.M.T == B.M.T).
+Proof.
+  Reflexivity.
+Qed.
+
+Lemma a : (A.M.A == B.M.A).
+Proof.
+  Reflexivity.
+Qed.
+