BUG (1.5.19-4): libdl.a is missing

BUG (1.5.19-4): libdl.a is missing

[Daniel Santos]

cygwin (as in the base cygwin package) is missing /lib/libdl.a.  The 
install for the cygwin package should create a symlink with this name 
that links to libcygwin.a in the same directory.  Otherwise, builds for 
a lot of different software packages are broken.  Example is bash-3.1.  
It will die at this point:

gcc -DHAVE_CONFIG_H -DSHELL  -I. -I.. -I../include -I../lib -g 
-DCROSS_COMPILING -o mkbuiltins mkbuiltins.o -ldl
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/bin/ld: 
cannot find -ldl
collect2: ld returned 1 exit status

Create the above symlink and everybody is happy, nobody has to die...

Note:  It was a pain in the ass to figure out how to report and bug.  
Would be nice if there was a bug database or something.  Will be worse 
if I have to subscribe to this list to post to it.

Daniel
-- 

dd if=/dev/zero of=/ram/awsomeswap bs=1024 count=16384
mkswap -v0 /ram/awsomeswap 16384
/bin/sync
/sbin/swapon /ram/awsomeswap


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Re: BUG (1.5.19-4): libdl.a is missing

[Christopher Faylor]

On Sat, Jun 03, 2006 at 01:58:14AM -0700, Daniel Santos wrote:
>cygwin (as in the base cygwin package) is missing /lib/libdl.a.  The 
>install for the cygwin package should create a symlink with this name 
>that links to libcygwin.a in the same directory.  Otherwise, builds for 
>a lot of different software packages are broken.  Example is bash-3.1.  
>It will die at this point:
>
>gcc -DHAVE_CONFIG_H -DSHELL  -I. -I.. -I../include -I../lib -g 
>-DCROSS_COMPILING -o mkbuiltins mkbuiltins.o -ldl
>/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/bin/ld: 
>cannot find -ldl
>collect2: ld returned 1 exit status
>
>Create the above symlink and everybody is happy, nobody has to die...

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.

>Note:  It was a pain in the ass to figure out how to report and bug.  
>Would be nice if there was a bug database or something.

There is a "Reporting Problems" link on nearly every page of the cygwin
web site.

>Will be worse if I have to subscribe to this list to post to it.

http://cygwin.com/lists.html states which mailing lists are moderated.
You've just discovered that the main cygwin list is not one of them.

Phew.  I guess we dodged that bullet, at least.  I almost came >this<
close to having to refund all of your money for the inconvenience you've
suffered.

cgf

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Re: BUG (cygwin 1.5.19-4): libdl.a is missing

[Eric Blake]

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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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Re: BUG (cygwin 1.5.19-4): libdl.a is missing

[Christopher Faylor]

On Sat, Jul 15, 2006 at 07:21:53AM -0600, Eric Blake wrote:
>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:

What is a "dynamic library"?  Do you mean a dll?  How did libtool deal
with libc.a, libm.a, etc.?

FWIW, my level of caring about libtool issues is not very high so if
there is a solution here, it's in libtool not in cygwin.  I'm not going
to make accommodations in cygwin because a tool which is supposed to
"streamline" the building of libraries is too stupid to do it right.

There doesn't have to be a one-to-one correspondence between the name
of a library and a DLL so libtool really seems to be broken if it assuming
that because there is a libdl.a there must also be a cygdl.dll.

cgf

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