> > % ocamlopt -c  -I +libMagick  magick.cmxa   app.ml
> > % ocamlopt -output-obj -o mlobj.o unix.cmxa -I +libMagick magick.cmxa \
> >       app.cmx
> > (untill there, no error messages) 
> >
> > % gcc `Magick-config --cflags --cppflags`  main.c  -o myapp.opt  mlobj.o \
> >         -I'/usr/local/lib/ocaml' \
> >         -L/usr/local/lib/ocaml \
> >         -lunix -lasmrun  -lm -ldl \
> >         `Magick-config --ldflags --libs`
> >
> > and then with this last command, I get about 200 errors like this:
> > [...]

Indeed, the solution was to give the stubs of the binding to gcc:

% ls /usr/local/lib/ocaml/libMagick/
dllmagick_stubs.so  libmagick_stubs.a  magick.a  magick.cma  magick.cmi  
magick.cmxa  magick.mli

% gcc \
        `Magick-config --cflags --cppflags` \
        main.c  -o myapp.opt  mlobj.o \
        -I'/usr/local/lib/ocaml' \
        -L/usr/local/lib/ocaml \
        -lunix -lasmrun  -lm -ldl \
        `Magick-config --ldflags --libs` \
        -L/usr/local/lib/ocaml/libMagick  \
        -lmagick_stubs


++ Thanks a lot to Jonathan and Rabih for your help !

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