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Date: -- (:)
From: Christian Lindig <lindig@i...>
Subject: ocamlopt and ocamldep

The ocamldep utility in OCaml 2.0 creates for a file concept.mli that
uses modules Bitrelation and Bitset a dependency of the following
form:

        concept.cmi: bitrelation.cmo bitset.cmo

When compiling for native code this causes uncessessary recompilations 
of the files bitrelation.ml and bitset.ml:

        % make colibri.cmxa 
        ocamlopt.opt -I ../libcolibri -I ../getopt   -c stat.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c stat.ml
   -->  ocamlopt.opt -I ../libcolibri -I ../getopt -c bitset.ml
   -->  ocamlopt.opt -I ../libcolibri -I ../getopt -c bitrelation.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt   -c intcode.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c intcode.ml
   ==>  ocamlc -I ../libcolibri -I ../getopt   -c bitset.ml
   ==>  ocamlc -I ../libcolibri -I ../getopt   -c bitrelation.ml
   -->  ocamlopt.opt -I ../libcolibri -I ../getopt   -c concept.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c concept.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt   -c lattice.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c lattice.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -c context.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -a -o colibri.cmxa 
            stat.cmx bitset.cmx bitrelation.cmx intcode.cmx concept.cmx 
            lattice.cmx context.cmx
      
bitset.ml and bitrelation are already compiled to *.cmx, *.cmi, and
*.o. Because of the dependency generated by ocamldep they get
recompiled using the *byte* code compiler and thus new *.cmi files are
created as well.

This does not matter in most cases since OCaml compiles very fast. I
suspect the recompilation to cause subtle 'inconsistent assumptions
over interface' errors in conjunction with -unsave -noassert compiler
flags. However, I was not able to find a small example for this mail
that reproduces the error.

Should cmi-files depend on cmx-files when compiling for native code?
This would avoid uneccessary recompilations but would also make
integrating byte code compilation and native code compilation into one
Makefile much harder.

-- Christian

------------------------------------------------------------------------------
Christian Lindig                  http://www.cs.tu-bs.de/softech/people/lindig 
                                  mail:  lindig@ips.cs.tu-bs.de