Re: switching to `ocamlc -where` = /usr/lib/ocaml/

[Richard Jones <rich@annexia.org>]

On Mon, Feb 09, 2009 at 10:07:24AM +0100, Stefano Zacchiroli wrote:
> The proposal is to switch from having `ocamlc -where` =
> /usr/lib/ocaml/<ABI>/ to plain /usr/lib/ocaml/.

I'll put my two cent(ime)s in here:

Fedora uses $libdir/ocaml (ie. no versioned directory) for the same
reason you mention.  So we can only support installing one version of
OCaml at a time.

_However_ when it comes to installing the cross-compiler, we use a
separate library directory and separate binaries:

  $libdir/$target-ocaml     # The OCaml library, cross-compiled
  $bindir/$target-ocamlopt  # The cross-compiler

where $target is something like "i686-pc-mingw32", but we expect to
have other cross-compilers in future.

Note that if you use AC_CHECK_TOOL([ocamlopt]) in autoconf, and you
are cross-compiling, then autoconf automatically picks
/usr/bin/$target-ocamlopt over /usr/bin/ocamlopt.

Now the way we chose to select between ordinary compilation and
cross-compilation is elegant and works even without autoconf.  We
have two ocamlfind.conf files:

  /etc/ocamlfind.conf       # Selects ordinary compilation
  /etc/i686-pc-mingw32-ocamlfind.conf  # Selects cross-compilation

and to switch between the two, just set OCAMLFIND_CONF environment
variable to point to the correct configuration file (actually, to
select ordinary compilation, you just leave this undefined).  Ordinary
ocamlfind commands just work, but pick the correct compiler:

  ocamlfind ocamlopt -package ......

Rich.

-- 
Richard Jones
Red Hat