Re: shared library linking on Darwin

[Chris Leishman]

On Tuesday, April 17, 2001, at 01:50  PM, Alexandre Oliva wrote:

> On Apr 17, 2001, Chris Leishman <address@hidden> wrote:
>
> > *** Warning: This library needs some functionality provided by
> > extra/libextra.a.
>
> > Unfortunately I can't get the application to load the libshared.a file
> > as a dynamic module (not unsurprising).  Even if I specify -dlopen on
> > the command line it still barfs
>
> How exactly are you specifying this flag, and what exactly happens?

I'm using automake, and I add it to the binary_LDFLAGS option, which 
adds it to the link line.
Everything compiles ok, but the dlopen fails with the error "not a 
Mach-O MH_BUNDLE file type" (this error message is output by dlcompat 
when NSCreateObjectFileImageFromFile returns 
NSObjectFileImageInapproriateFile).


> > I'm just wondering why it can't just suck the object files out of the
> > archive when linking the shared library?
>
> Because they're likely to be non-PIC, and several platforms don't
> support non-PIC in shared libraries.  If Darwin does, all you have to
> do is to post a patch that sets deplibs_check_method=pass_all.

Yeah....I thought the PIC might be an issue - I just wasn't sure...

> > That seems to be how it works on other platforms.
>
> You haven't tested on enough other platforms :-)

Thats entirely reasonable!  I've only tried this on Solaris/Linux/BSD 
which isn't exactly alot.
I just hoped Darwin would have some similarities with BSD - but that was 
a huge long shot considering its shared library system appears to be 
totally different (weird Mach junk ;-) ).

> > Alternatively I can compile the subdir as a shared library, but that
> > means I need to use inter library dependencies when module loading -
>
> Compile it as a libtool convenience archive.  That's exactly the
> purpose of this feature.

I tried that, but I still get the error:

*** Warning: inter-library dependencies are not known to be supported.
*** All declared inter-library dependencies are being dropped.

*** Warning: libtool could not satisfy all declared inter-library
*** dependencies of module module.  Therefore, libtool will create
*** a static module, that should work as long as the dlopening
*** application is linked with the -dlopen flag.


And the result is a static archive library (as stated in the warning).

I'm sending you an example module in a separate mail (not CC'd to the 
list), which will show you how I've set up the build environment.

Thanks,

Chris