Re: Build system/cygwin question

From: Jerome Lecomte (jlecomte_at_[hidden])
Date: 2001-06-16 12:58:57

Greg, Dave

I had read these messages before but couldn't get it to work. I am 
sure I did something wrong but couldn't figure what.

This lead me to the dllwrap alternative by Mumit Khan. I zipped the
little toy project I made to test it and made it available on the 
vault. It seems to initialize the static object correctly and cope 
with dlopen/dlsym/dlclose.

One thing though. As pointed out by Greg .so extension is replaced 
with .dll. 

JL

--- In boost_at_y..., Greg Chicares <chicares_at_m...> wrote:
> David Abrahams wrote:
> > 
> > Is anyone out there familiar with building shared libraries under 
Cygwin?
> > 
> > Does "g++ -shared" work?
> 
> Yes.
> 
> > When I tried it with a simple test program, I got:
> >   Cannot export _bss_end__: symbol not defined
> >   Cannot export _bss_start__: symbol not defined
> >   Cannot export _data_end__: symbol not defined
> >   Cannot export _data_start__: symbol not defined
> >   collect2: ld returned 1 exit status
> 
> This message might help
>   http://www.cygwin.com/ml/cygwin/2001-03/msg00589.html
> If the code has to do with python, try this one:
>   http://www.mail-archive.com/cygwin@s.../msg11037.html
> 
> > Does it generate .so files that can be used in the usual unix 
fashion?
> 
> Ummm...it generates .dll files that can be used in the usual
> windows fashion. I don't know enough about unix to say how
> that differs.
> 
> > I realize there's something called dlltool; is that just for 
generating
> > windows-standard DLLs, or is that the only way to generate a 
proper shared
> > library with cygwin?
> 
> dlltool is rarely needed. Go here
>   http://sources.redhat.com/cygwin/faq/faq_4.html#SEC97
> and follow the link to
>   http://cygwin.com/ml/cygwin/2000-06/msg00688.html
> Where it says
> | To compile bar.exe to use the DLL:
> | 
> |    gcc -DUSEDLL -c bar.c -o bar.exe
> |    gcc bar.o libfoo.import.a -o bar.exe
> | 
> | That's all there is to it.
> make this change:
> -    gcc -DUSEDLL -c bar.c -o bar.exe
> +    gcc -DUSEDLL -c bar.c -o bar.o
> I just verified that this works with the latest cygwin,
> which uses gcc-2.95.3-4 .