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[Caml-list] [long] not-so-static binaries on Mac OS X
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Date: -- (:)
From: Stefano Zacchiroli <zack@b...>
Subject: [Caml-list] [long] not-so-static binaries on Mac OS X
I'm working on the Mac OS X porting of an OCaml (native code)

I had no problem in making the application compile and run on Mac OS X
using additionally packages from the fink (
project (like ocaml itself) and some other hand installed ocaml

I only encountered problems while trying to distribute the resulting
binaries. Naively compile in native code results, as usual, in a
dynamically linked executable. Unfortunately most of those dependencies
are easily resolvable only using some fink packages, but I don't want to
force the final user of the application to install fink: is huge and I
think is a bit against the standard installation easyness of Mac OS X.

So I tried to compile passing "-static" to the C linker. This doesn't
work and his highly discouraged by Apple that additionally states that
"static linking of users binaries is not supported on Mac OS X"

My next aim was therefore to statically link only certain libraries (in
my case all the ocaml related libraries) and dinamically link only
against the Mac OS X library: "/usr/lib/libSystem.B.dylib".

This turns out to be far from easy, the only working solution I've found
so far is as follow:
- execute the final ocamlopt linking run passing "-verbose" (this shows
  you the execution of an assembly pass on a /tmp/<caml ... .s>
  generating a /tmp/<caml ... .o> object and an execution of gcc linking
  all the objects including the .o in /tmp
- hit CTRL-C (!!!!) just after the .o in /tmp has been created (to avoid
  that it will be deleted [no, "-S" doesn't help here])
- manually execute the final gcc linking command replacing each
  undesired "-l" switch with the corresponding .a library

The result turns out to dynamically depends only on the desired system

Ok, but this seems to me a bit tricky ... is not funny to do that for
all the needed executables and for each new release of the application

The problem is that there is no way to tell ocamlopt to _remove_ a
linker switch while invoking the linker. You can just _add_ switches
(with "-cclib"), but if the linker find both a "-l" switch and a static
".a" library it prefers the dynamic linking.

I've looked at the native code compiler code and is possible to
selectively remove some "-l" switches, but it's a bit tricky because
those switches could come from different "sources". I can try to add a
-rmccopt/-rmcclib switch to ocamlopt but before doing that I would like
to be sure that:
1) there is no other way to do what I'm trying to do
2) such a patch is welcome upstream


Stefano Zacchiroli  --  Master in Computer Science @ Uni. Bologna, Italy
zack@{,,}  -
"  I know you believe you understood what you think I said, but I am not
sure you realize that what you heard is not what I meant!  " -- G.Romney

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