Re: Mac OS X .dylib not working

[Peter O'Gorman <peter@pogma.com>]

On 03/03/2011 01:56 PM, Michael Ellis wrote:
> On Thu, Mar 3, 2011 at 2:32 PM, Hans Åberg<hans.aberg-1@telia.com>  wrote:
>> [I'm not on the bug-libtool list, so please cc me.]
>>
>> Despite being reported a year ago, Guile can still not open dynamic libraries ending with .dylib on Mac OS X. Looking throw the past discussion, it looks as though developers of the one package hold the opinion that those of the other package should do the fix. So I am merely reporting it, cross-linking, so that you can figure out who guys should do the fix. :-)
>>
>> So guile-2.0.0 using libltdl.7.dylib of libtool-2.4, can on Mac OS X 10.6.6 only open a dynamic library if the name of what it actually opens ends in .so (say by making a soft link using 'ln -s'); if it ends in .dylib, it cannot open it, even if the full name is given.
>>
>> See
>>   http://lists.gnu.org/archive/html/bug-guile/2011-03/msg00008.html
>>   http://lists.gnu.org/archive/html/guile-devel/2011-03/msg00021.html
>>
>> Mac OS X does not care about file name extensions; .dylib is just a convention for native dynamic libraries.

The static linker when it sees a -l flag will look for files beginning 
with "lib" and ending in ".dylib", ".so" (though this is recent and 
perhaps not documented) and ".a". So, I think you could say that it 
cares about file name extensions.

>>
>> So the wanted behavior is to first try opening a library without adding an extension, and then try out different endings. On Mac OS X, it would be best trying out .dylib first - I haven't seen any other ending in use.

It does seem as though guile should sometimes be trying lt_dlopen() 
first - then libltdl will attempt to open whatever it's given.

>
>   -- the libtool archive extension .la
>   -- the extension used for native dynamically loadable modules on the
> host platform, e.g., .so, .sl, etc.

On Mac OS X, libtool's idea of the native dynamically loadable module 
extension is ".so", and it's not going to change.

However, I can see the point that libltdl should try .dylib as well as 
.so for lt_dlopenext on Mac OS X. I will come up with a patch for that.

Peter