[Caml-list] Unused .cma and .so

[Caml-list] Unused .cma and .so

[Claudio Sacerdoti Coen]

 Hi OCamlers,

 I used to think that linking a .cma when no module inside it is required
 is completely hurtless. I was wrong: it seems that .so added during linking
 of those .cma are loaded. To me, this seems a feature with a
 counter-intuitive semantics.

 Is there any way to disable this behaviour?

 				Thanks in advance,
				     C.S.C.

-- 
----------------------------------------------------------------
Real name: Claudio Sacerdoti Coen
PhD Student in Computer Science at University of Bologna
E-mail: sacerdot@cs.unibo.it
http://caristudenti.cs.unibo.it/~sacerdot
----------------------------------------------------------------
-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners

Re: [Caml-list] Unused .cma and .so

[Warp]

>  I used to think that linking a .cma when no module inside it is required
>  is completely hurtless. I was wrong: it seems that .so added during
linking
>  of those .cma are loaded. To me, this seems a feature with a
>  counter-intuitive semantics.
>
>  Is there any way to disable this behaviour?

You have to link your binary using the -noautolink ocamlc parameter.
( Watch the ocaml manual )

Nicolas Cannasse

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners

Re: [Caml-list] Unused .cma and .so

[Claudio Sacerdoti Coen]

> You have to link your binary using the -noautolink ocamlc parameter.
> ( Watch the ocaml manual )

 I already knew that parameter, but it is not what I would like to have.
 Here comes the problem with more informations: when using findlib with
 libraries providing more than one .cma (e.g. lablgtk), I expect
 findlib to add to the linking phase every .cma and ocamlc to not consider
 all the unuseful ones. Since ocamlc still considers the linking options of
 the .cma, I can't no more use findlib in that way and I have to add
 O(2^n) rules to the META file to choose exactly which .cma to add.
 If I use the -noautolink option, instead, it effects every .cma
 (even the ones belonging to other packages) and I have to add many many
 linking options by hand (and so why should I use findlib or something
 similar at all?)

 I hope to have been more clear.

 					Regards,
					 C.S.C.

-- 
----------------------------------------------------------------
Real name: Claudio Sacerdoti Coen
PhD Student in Computer Science at University of Bologna
E-mail: sacerdot@cs.unibo.it
http://caristudenti.cs.unibo.it/~sacerdot
----------------------------------------------------------------
-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners

Re: [Caml-list] Unused .cma and .so

[Xavier Leroy]

>  I used to think that linking a .cma when no module inside it is required
>  is completely hurtless. I was wrong: it seems that .so added during linking
>  of those .cma are loaded. To me, this seems a feature with a
>  counter-intuitive semantics.
>  Is there any way to disable this behaviour?

No, because it is actually necessary.

External functions declared in .mli files are expanded inline into
client code.  For instance, if we have a module A with signature

        external f : ... = "my_f"
        val g : ...

references to A.f in client code are expanded inline into C calls to "my_f",
while references to A.g leave an explicit reference to A in client code.

Now, assume that we have a.cma composed of the module A above and of
a C library dlla.so defining my_f.  If the client code never references A.g,
the linker will correctly discard the Caml code for A.  However, it
must link dlla.so so that inlined references to "my_f" are satisfied.  

If you're linking with ocamlopt or ocamlc -custom, the C linker will
be passed liba.a and will actually discard it if there are no
references to my_f.  But doing the same thing with the pure bytecode
compiler ocamlc is very hard: there is no standard API to examine
the dependencies of DLLs, and the C part of a library can reference
directly functions form the C part of another library.

- Xavier Leroy
-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners

Re: [Caml-list] Unused .cma and .so

[Claudio Sacerdoti Coen]

> No, because it is actually necessary.
> External functions declared in .mli files are expanded inline into
> client code.

 I see. This is also documented in the manual (17.1.1).
 Can I suggest to stress that also in 8.1 (in the .cma explanation,
 just after the paragraph explaining that unuseful .cmo files are not
 linked)?

					Regards,
					C.S.C.

-- 
----------------------------------------------------------------
Real name: Claudio Sacerdoti Coen
PhD Student in Computer Science at University of Bologna
E-mail: sacerdot@cs.unibo.it
http://caristudenti.cs.unibo.it/~sacerdot
----------------------------------------------------------------
-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners