unexpected emergence of --whole-archive

[Matěj Týč]

Hello,
I use autotools libtool to make a library. That library consists of the
main shared library file and a set of dynamically loadable modules.
Those modules depend on external shared libraries.
I have written configure.ac and Makefile.am that are quite complex and
some things are generated during the configure time (it is an image
loading library supporting quite a lot of formats). So I can't post
stuff here, there is too much of it.

The problem is: During the build of libraries, some modules refuse to
build. The cause is, however, absolutely strange.
During the 'make' phase, the following happens:

/bin/sh ../libtool --tag=CC   --mode=link gcc  -DNOINLINE -Wextra -g -O0
-module  -lpng12   -o png.la -rpath /usr/local/lib/IL png_la-il_png.lo
-lm -lz
results in:
libtool: link: gcc -shared  .libs/png_la-il_png.o   -lpng12 -lm -lz
-Wl,-soname -Wl,png.so.0 -o .libs/png.so.0.0.0
That is OK. However:

/bin/sh ../libtool --tag=CC   --mode=link gcc  -DNOINLINE -Wextra -g -O0
-module  -ljpeg   -o jpeg.la -rpath /usr/local/lib/IL jpeg_la-il_jpeg.lo
-lm -lz 
results in:
libtool: link: gcc -shared  .libs/jpeg_la-il_jpeg.o
-Wl,--whole-archive /home/bubla/projects/devil_modular/lib/.libs/libjpeg.a 
-Wl,--no-whole-archive  -ljpeg -lm -lz    -Wl,-soname -Wl,jpeg.so.0 -o 
.libs/jpeg.so.0.0.0
and consequently an error occurs:
gcc: /home/bubla/projects/devil_modular/lib/.libs/libjpeg.a: No such
file or directory

To have something to start with, you have an idea where does that
-Wl,--whole-archive <bla bla> -Wl,--no-whole-archive section come from?

Regards,
Matej