From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105])
	by walapai.inria.fr (8.13.6/8.13.6) with ESMTP id p6QMkJA5008534
	for <caml-list@sympa-roc.inria.fr>; Wed, 27 Jul 2011 00:46:19 +0200
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AtQCAOVCL07RVdIyimdsb2JhbAA1AQEBAQMUAhcTCAE8AQMNAQYFQBIUJgEFASQHPpthi0EIFAEBAQoJDQcSBiGtVgqOeoR4iScCAwaFW18Eh1WLHYYtgz2CXjyBP4Is
X-IronPort-AV: E=Sophos;i="4.67,272,1309730400"; 
   d="scan'208";a="103953534"
Received: from mail-pz0-f50.google.com ([209.85.210.50])
  by mail4-smtp-sop.national.inria.fr with ESMTP/TLS/RC4-SHA; 27 Jul 2011 00:46:13 +0200
Received: by pzk2 with SMTP id 2so1670562pzk.37
        for <caml-list@inria.fr>; Tue, 26 Jul 2011 15:46:11 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=gamma;
        h=sender:subject:mime-version:content-type:from:in-reply-to:date:cc
         :content-transfer-encoding:message-id:references:to:x-mailer;
        bh=f5sZW4ev6E2jkGbLvHuzR+700q1d8jXorPSxPGUYIzI=;
        b=g/2X55Nf6m2H8sJiL3KF7li+SN4DFcvsZU4XJxn64n0gO39OPjOWdYLMV4HL3UX73i
         WFlPr/hk2Auqj7Gt/XkOnuemIFogv02Q9MsdzgeoK5y+0uS2UQfJv+VyduomzsK6saNo
         RJ0XF0qzCBUABdcwJfzG9OVNMaLuv2R+ZeXCg=
Received: by 10.68.62.197 with SMTP id a5mr10976752pbs.494.1311720371406;
        Tue, 26 Jul 2011 15:46:11 -0700 (PDT)
Received: from tanpopo.garrigue.jp (58x158x128x157.ap58.ftth.ucom.ne.jp [58.158.128.157])
        by mx.google.com with ESMTPS id e6sm994152pbm.71.2011.07.26.15.46.08
        (version=TLSv1/SSLv3 cipher=OTHER);
        Tue, 26 Jul 2011 15:46:09 -0700 (PDT)
Sender: Jacques Garrigue <jacques.garrigue@gmail.com>
Mime-Version: 1.0 (Apple Message framework v1084)
Content-Type: text/plain; charset=us-ascii
From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
In-Reply-To: <CANGFCiDQJPEAuWFo8MgQYQuOapUE_FMRsPCq8kR+scikeRJsBQ@mail.gmail.com>
Date: Wed, 27 Jul 2011 07:46:09 +0900
Cc: caml-list <caml-list@inria.fr>
Message-Id: <955FD80F-3BD7-41C3-917F-A3FC024CD0DD@math.nagoya-u.ac.jp>
References: <CANGFCiDQJPEAuWFo8MgQYQuOapUE_FMRsPCq8kR+scikeRJsBQ@mail.gmail.com>
To: Polux Moon <polux.moon@gmail.com>
X-Mailer: Apple Mail (2.1084)
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by walapai.inria.fr id p6QMkJA5008534
Subject: Re: [Caml-list] Problem with forall and method

This is a bug.
Please report to http://caml.inria.fr/mantis

Jacques Garrigue

On 2011/07/26, at 21:17, Polux Moon wrote:

> (Sorry for duplicate mail, I forgot to change the subject in the first one)
> 
> Hi,
> 
> I have a type error on code similar to :
> 
> -----
> type 'par t = 'par
> 
> let ident v = v
> 
> class alias =
> object
>   method alias : 'a . 'a t -> 'a = ident (* type error here *)
> end
> -----
> 
> Which gives :
> 
> -----
> Error: This expression has type 'a. 'a t -> 'a
>        but an expression was expected of type 'b. 'b t -> 'b
>        Type 'a a = 'a is not compatible with type 'b t = 'b
> -----
> 
> The problem is related to unification of foralls containing named type in a method.
> The compiler accepts equivalent code when not using the named type "t" or when not using a method (see attached file).
> 
> Is it a [known] limitation ? Is there a way to work around it ?
> 
> <forallclass.ml>