[Caml-list] Re: Link problems when startup from C++

[Kakadu <kakadu.hafanana@gmail.com>]

Issue is fixed now.

1. It is wrong to add  linking information while generating .o file
from OCaml .cmx files. Object files can't contain information about
dependencies, it is external. So right command was

ocamlfind opt -package compiler-libs.common,unix -linkpkg -output-obj
-dstartup -I ../_build ../_build/qml_wrap.cmxa \
        DataItem.cmx MainModel.cmx MiniModel.cmx program.cmx -linkall
-o camlcode.o

After that unix.a will be inside camlcode.o.

2. I needed to add linking commands to GCC call. Like this:

g++ -L$QT5_ROOT/qtbase/lib -lQt5Core -lQt5Qml -lQt5Quick -lQt5Gui
-L`ocamlc -where` \
        ../_build/stubs.o <C++ and OCaml object files> -lm  -ldl -lasmrun \
        -lunix -o main

Parameter '-lunix' adds 'libunix.so' file to 'main' executable. This
shared object contains implementation of stubs declared in unix.a.

N.B. Order of arguments should be correct. When I put -lunix just
after '-L`ocamlc -where`' linking have finished with same errors like
in first letter.


--------------
Kakadu



On Sun, Mar 24, 2013 at 12:00 PM, Kakadu <kakadu.hafanana@gmail.com> wrote:
> Hey
>
> My OCaml code uses Unix findlib package and I compile it like this
>
> ocamlfind opt -package compiler-libs.common,unix -linkpkg -output-obj
> -dstartup -I ../_build ../_build/qml_wrap.cmxa \
>         -ccopt -L`ocamlc -where` -ccopt -lunix \
>         DataItem.cmx MainModel.cmx MiniModel.cmx program.cmx  -linkall
> -o camlcode.o -verbose
> Effective set of compiler predicates:
> pkg_compiler-libs,pkg_compiler-libs.common,pkg_unix,autolink,native
> + ocamlopt.opt -output-obj -dstartup -I ../_build -ccopt
> -L/home/kakadu/.opam/4.00.1/lib/ocaml -ccopt -lunix -linkall -o
> camlcode.o -verbose -I
> /home/kakadu/.opam/4.00.1/lib/ocaml/compiler-libs
> /home/kakadu/.opam/4.00.1/lib/ocaml/compiler-libs/ocamlcommon.cmxa
> /home/kakadu/.opam/4.00.1/lib/ocaml/unix.cmxa ../_build/qml_wrap.cmxa
> DataItem.cmx MainModel.cmx MiniModel.cmx program.cmx
> + as -o '/tmp/camlstartup3ada06.o' 'camlcode.o.startup.s'
> + ld -r  -o 'camlcode.o' '/tmp/camlstartup3ada06.o' 'program.o'
> 'MiniModel.o' 'MainModel.o' 'DataItem.o' '../_build/qml_wrap.a'
> '/home/kakadu/.opam/4.00.1/lib/ocaml/unix.a'
> '/home/kakadu/.opam/4.00.1/lib/ocaml/compiler-libs/ocamlcommon.a'
> '/home/kakadu/.opam/4.00.1/lib/ocaml/stdlib.a'
>
> It seems that Unix should be statically linked to 'camlcode.o'. After
> that I want to build executable.
>
> g++ -L$QT5_ROOT/qtbase/lib -lQt5Core -lQt5Qml -lQt5Quick -lQt5Gui
> -L"`ocamlc -where`" -lunix \
>         ../_build/stubs.o DataItem_c.o moc_DataItem_c.o MainModel_c.o
> moc_MainModel_c.o MiniModel_c.o moc_MiniModel_c.o camlcode.o main.o
> -lm  -ldl -lasmrun \
>         -o main
>
> And I get many error like this:
>
> camlcode.o: In function `camlProgram__files_in_dir_1009':
> (.text+0x399a): undefined reference to `unix_opendir'
> /home/kakadu/.opam/4.00.1/build/ocaml/otherlibs/unix/unix.ml:644:
> undefined reference to `unix_close'
> camlcode.o: In function `camlUnix__fun_2465':
> /home/kakadu/.opam/4.00.1/build/ocaml/otherlibs/unix/unix.ml:644:
> undefined reference to `unix_close'
> camlcode.o: In function `camlUnix__fun_2157':
> /home/kakadu/.opam/4.00.1/build/ocaml/otherlibs/unix/unix.ml:644:
> undefined reference to `unix_setsid'
> camlcode.o: In function `camlUnix__fun_2159':
> /home/kakadu/.opam/4.00.1/build/ocaml/otherlibs/unix/unix.ml:644:
> undefined reference to `unix_tcflow'
> camlcode.o: In function `camlUnix__fun_2161':
> /home/kakadu/.opam/4.00.1/build/ocaml/otherlibs/unix/unix.ml:644:
> undefined reference to `unix_tcflush'
> etc.
>
> Any ideas what I have done wrong? How to link to unix correctly?
>
> Kind regards,
> Kakadu