[Caml-list] OASIS and conditional compilation

[Dario Teixeira <darioteixeira@yahoo.com>]

Hi,

I've come across a perplexing issue with OASIS.  I'm not sure if this is
just a bug or if I'm trying to push the tool beyond its design parameters.

PG'OCaml can be compiled against either Batteries or ExtLib (the latter
mostly for legacy compatibility). To allow the harmonious coexistence of
the two options in the same system, the build system should allow for
the compilation of one or the two versions of the library side by side.
In OASIS-speak (I'm using version 0.3):

  Flag "batteries"
    Description: Link PG'OCaml against Batteries
    Default: true

  Flag "extlib"
    Description: Link PG'OCaml against ExtLib
    Default: true

  Library "pgocaml_batteries"
    Build$:               flag(batteries)
    Install$:             flag(batteries)
    Path:                 src
    Modules:              PGOCaml, PGOCaml_generic
    BuildDepends:         unix, calendar, csv, pcre, batteries, camlp4.macro
    ByteOpt+:             -ppopt -DUSE_BATTERIES
    NativeOpt+:           -ppopt -DUSE_BATTERIES
    FindlibContainers:    pgocaml
    Findlibname:          batteries
    XMETARequires:        unix, calendar, csv, pcre, batteries

  Library "pgocaml_extlib"
    Build$:               flag(extlib)
    Install$:             flag(extlib)
    Path:                 src
    Modules:              PGOCaml, PGOCaml_generic
    BuildDepends:         unix, calendar, csv, pcre, extlib, camlp4.macro
    FindlibContainers:    pgocaml
    Findlibname:          extlib
    XMETARequires:        unix, calendar, csv, pcre, extlib

Note that the major difference is that "-ppopt -DUSE_BATTERIES" must be
passed to Camlp4 only when compiling the Batteries version.  The problem
is that it's *always* passed, even if the "batteries" flag is disabled
by passing "--disable-batteries" to the configure script.

Did I misinterpret something crucial about OASIS, or is this indeed a bug?

Thanks in advance!
Best regards,
Dario Teixeira

P.S. The full OASIS spec file can be viewed at this location:
     https://forge.ocamlcore.org/scm/viewvc.php/branches/oasification/_oasis?revision=157&root=pgocaml