X-Recipient: archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status: No, hits=-1.8 required=5.0 	tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,TW_XD,T_TO_NO_BRKTS_FREEMAIL
X-Spam-Check-By: sourceware.org
Message-ID: <4BBD1953.4070703@users.sourceforge.net>
Date: Wed, 07 Apr 2010 18:46:27 -0500
From: "Yaakov (Cygwin/X)" <yselkowitz AT users DOT sourceforge DOT net>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: weak symbols on Cygwin
References: <4BBB31C6 DOT 7080703 AT redhat DOT com> <201004070141 DOT 36284 DOT bruno AT clisp DOT org> <4BBBF5C2 DOT 30102 AT gmail DOT com> <201004071106 DOT 11471 DOT bruno AT clisp DOT org>
In-Reply-To: <201004071106.11471.bruno@clisp.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On 2010-04-07 04:06, Bruno Haible wrote:
> I was implicitly hoping that
>    - gcc would collect all weak-declared symbols in some table, and
>      generate code so that the reference to these symbols makes an indirection
>      through this table,
>    - the Cygwin runtime would call dlsym or GetProcAddress at startup and
>      fill in addresses into said table.

This is essentially what FlexDLL[1] does, as used by OCaml to support 
shared stublibs and natdynlink modules on PE platforms.  The major 
drawback to FlexDLL (besides being nearly impossible to understand 
because most of it is written in OCaml :-)) is that all link commands 
must be passed through its flexlink command.

I suppose a possible solution would be to port flexlink to C as part of 
gcc (or ld?) and merge the flexdll_*() functionality into Cygwin.  That 
would be way beyond me, however; I barely managed to learn enough about 
OCaml to add some patches[2] necessary for a Cygwin-native flexdll 
package for Ports.

[1] http://alain.frisch.fr/flexdll.html
[2] 
http://cygwin-ports.svn.sourceforge.net/viewvc/cygwin-ports/ports/trunk/devel/flexdll/


Yaakov
Cygwin Ports

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple