Message-ID: <44B8EBF1.1010402@byu.net>
Date: Sat, 15 Jul 2006 07:21:53 -0600
From: Eric Blake <ebb9@byu.net>
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To: cygwin@cygwin.com, libtool@gnu.org
Subject: Re: BUG (cygwin 1.5.19-4): libdl.a is missing
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According to Christopher Faylor on 6/4/2006 5:38 PM:
> 
> I've added a libdl.a to the latest snapshot, however any project which
> relies on the existence of this library without checking to see if it
> exists is broken as far as portability is concerned.

By doing so, you broke CVS libtool (which will someday become libtool
2.0).  Now that libtool can find -ldl, but there is no dynamic library
behind it, libtool is now spitting out the following warning on every
attempt to create a dll that depends on libltdl:

*** Warning: linker path does not have real file for library -ldl.
*** I have the capability to make that library automatically link in when
*** you link to this library.  But I can only do this if you have a
*** shared version of the library, which you do not appear to have
*** because I did check the linker path looking for a file starting
*** with libdl and none of the candidates passed a file format test
*** using a file magic. Last file checked: /lib/libdl.a
*** The inter-library dependencies that have been dropped here will be
*** automatically added whenever a program is linked with this library
*** or is declared to -dlopen it.

*** Since this library must not contain undefined symbols,
*** because either the platform does not support them or
*** it was explicitly requested with -no-undefined,
*** libtool will only create a static version of it.

I don't know if the fix is providing a dynamic placeholder for libdl in
cygwin, or teaching libtool that -ldl should not be used by libltdl on
cygwin, although the latter sounds more appealing.

- --
Life is short - so eat dessert first!

Eric Blake             ebb9@byu.net
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