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From: Chris Faylor <cgf AT cygnus DOT com>
Date: Wed, 31 May 2000 19:13:54 -0400
To: cygwin AT sourceware DOT cygnus DOT com
Subject: Re: Major bug -- Exception handling broken
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In-Reply-To: <4.3.1.2.20000531185749.03b507f0@pop.ma.ultranet.com>; from lhall@rfk.com on Wed, May 31, 2000 at 07:08:41PM -0500

On Wed, May 31, 2000 at 07:08:41PM -0500, Larry Hall (RFK Partners, Inc) wrote:
>At 05:54 PM 5/31/00, Ross Smith wrote:
>>From: "Parker, Ron" <rdparker AT butlermfg DOT com>
>>>My hunch about the specs file was wrong.  There are no entries related
>>>to g++.  However I did track this down to a problem with g++ using
>>>libm.a.
>>> 
>>> [snip]
>>> 
>>> gcc -v foo.cpp -o foo -lstd++ (OKAY)
>>> gcc -v foo.cpp -o foo -lstd++ -lm(BAD)
>>> gcc -v foo.cpp -o foo -lm (BAD)
>>> 
>>> So the problem seems to be with libm.a.  
>>
>>Cygwin's libm.a is a symlink to libcygwin.a.  I'll try replacing it
>>with a dummy stub library ...  <tries it> ...  nope, that made ld
>>crash.
>
>Hm.  All this rings a bell with me.  Something very old and very
>foggy....  Seems to me I recall that multiple references to libraries
>in the link stream always caused Cygwin to crash.  I believe the
>context of this the last time the issue came up was with Windows
>libraries but perhaps the issue is more generic.  Also, I recall
>discussions which stated that there isn't really a libm.a for Cygwin.
>Its all in Cygwin.  That would imply that libcygwin.a == libm.a, a
>notion that the symlink tends to support.  Given all this, its my
>impression that libm.a isn't needed, at least in the default case.
>Obviously, eliminating libm.a as a default library to link against is
>not the complete solution since some packages are going to link against
>it explicitly in their makefile and therefore still see problem (unless
>the makefile is edited!;-))  Probably we'll need to wait for Mumit to
>clarify this whole situation but eliminating the -lm seems a good
>work-around for now!;-)

You're right that adding libm.a or libc.a to the link line can screw
up constructors in g++.  I thought that this was solved in the gcc
that we're releasing.  Guess not.

cgf

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