libtool dll creation (mingw32 undefined symbols)

[richard]

Hello list,
for a project i'd like to create a plugin mechanism, and don't want to 
be the bottleneck when the project is slowly made ready for cross 
compilation to win32.

I'd like to start slow by just crosscompile a executable and a dynamic 
library,
but i fail at building the .dll with libtool complaining about
> libtool: link: warning: undefined symbols not allowed in 
> i586-pc-mingw32msvc shared libraries
using:
automake 1.10
autoconf 2.1.6
libtool 1.5.22
gcc 4.1.2
mingw32 3.4.5
in debian unstable

The --no-undefined is set for the library, and i tried to follow the 
(maybe seriously outdated dll compilation howto from the autobook at 
http://sourceware.org/autobook/autobook/autobook_252.html#SEC252)

I also tried to __declspec(dllexport) but thought that this is for data 
export only -
so i think i got something wrong or don't fully understand what i am doing-
i would be very thankful for an simple howto or demo program which 
accomplishes what i am trying to do.
I took a look at the libltdl sources, because they compile perfectly as 
a dll, but did not manage to get much out of it.
So i am a little stuck at the moment.

here is more info how i try to get it done:
i configure it with
> ./configure --target=i586-mingw32msvc --host=i586-mingw32msvc 
> --build=i686-pc-linux-gnu --disable-static
there is a configure.ac and a Makefile am in my top-dir
and plugin.cpp plugin.h test.cpp and test.h in the src dir

their contents are:
Makfile.am:
> SUBDIRS = src
configure.ac:
> AC_PREREQ(2.50)
> AC_INIT([amplug],[1.0],address@hidden)
> AC_CONFIG_HEADERS([config.h])
> AM_INIT_AUTOMAKE([-Wall -Werror foreign])
>
> AC_PROG_CC
> AC_C_CONST
> AC_C_INLINE
>
> AC_LIBTOOL_WIN32_DLL
> AC_PROG_LIBTOOL
> AC_SUBST([LIBTOOL_DEPS])
>
> AC_LIB_LTDL
>
> AC_CONFIG_FILES([Makefile src/Makefile])
> AC_OUTPUT
src/Makefile.am
> lib_LTLIBRARIES = libtest.la
> libtest_la_SOURCES = test.cpp test.h
> libtest_la_LDFLAGS =  --no-undefined -version-info 0:0:0 -Wall -Werror 
> --debug
> libtest_la_CXXFLAGS = -Wall -Werror
> libtest_la_LIBADD = $(LIBADD_DL)
>
> bin_PROGRAMS = plug
> plug_SOURCES = plugin.cpp plugin.h
> plug_LDADD = libtest.la

src/test.h
> #ifndef TEST_H_
> #define TEST_H_
>
> #if HAVE_CONFIG_H
> #  include <config.h>
> #endif
> extern "C"{
>
> extern int computesomething(void);
>
> }
> #endif /*TEST_H_*/
src/test.cpp
> #include"test.h"
>
> int computesomething(void){
>         return 42;
> }
src/plugin.cpp
> #include"test.h"
> int main(int argc, char** args){
>         std::cout << "testing dll crosscompile" << std::endl;
>         std::cout << computesomething() << std::endl;
>         return 0;
> }

thanks in advance,
Richard