Add sharing constraints to lib/lin.{ml,mli}

Author: jmid

lib/lin.ml

@@ -327,7 +327,7 @@ module type Spec = sig
   val api : (int * t elem) list
 end
 
-module MakeCmd (ApiSpec : Spec) : Internal.CmdSpec = struct
+module MakeCmd (ApiSpec : Spec) : Internal.CmdSpec with type t = ApiSpec.t = struct
 
   type t = ApiSpec.t
 

lib/lin.mli

@@ -330,7 +330,7 @@ end
 
 (** {1 Generating a linearization testing module from an API} *)
 
-module MakeCmd (Spec : Spec) : Internal.CmdSpec [@alert "-internal"]
+module MakeCmd (Spec : Spec) : Internal.CmdSpec with type t = Spec.t [@alert "-internal"]
 (** Functor to map a combinator-based module signature description
     into a raw {!Lin} description.
     This functor is exposed for internal uses only, its API may change