Can't unset -arch x86_64 in portfile in Snow Leopard

[njbutko@…]

I'm trying to create a -arch i386 variant of a port, but as far as I can tell from the Guide and all my valiant attempts, there's no way to delete -arch x86_64 from the make flags.

My variant looks something like

variant SL_32bit description {Build in 32-bit mode on Snow Leopard.} {
        configure.args-delete "-arch x86_64"
        configure.cxxflags-append "-arch i386"
}

which leads to the following output:

 /usr/bin/g++-4.2 -DHAVE_CONFIG_H -I. -I. -I../.. -I. -I../../cxcore/include -I../.. -DNDEBUG -I/opt/local/include -Wall -fno-rtti -pipe -O3 -g -march=prescott -ffast-math -fomit-frame-pointer -O2 -I/opt/local/include -L/opt/local/lib -arch i386 -arch x86_64 -MT cxalloc.lo -MD -MP -MF .deps/cxalloc.Tpo -c cxalloc.cpp  -fno-common -DPIC -o .libs/cxalloc.o
g++-4.2: -E, -S, -save-temps and -M options are not allowed with multiple -arch flags

where the bug is "-arch i386 -arch x86_64". I have tried deleting from every known configure and build flag in the guide, and none of them works.

That the "-arch x86_64" is there at all seems amiss. I do not have build_arch set in macports.conf, and g++ builds in 64-bit mode by default in Snow Leopard, so at best it is redundant. I don't want to set "build_arch" in macports.conf because it is not needed for all ports, and breaks many of them. I simply want to turn it on in this variant in this portfile. In searching the documentation and other tickets, I can't find a good answer for how to do so.

The portfile in question never touches build_arch or sets -arch (except for my variant):

# $Id: Portfile 50984 2009-05-14 21:08:43Z and.damore@macports.org $

PortSystem                      1.0

name                            opencv
version                         1.0.0
categories                      graphics science
platforms                       darwin
maintainers                     gmail.com:stante
description                     Intel(R) Open Source Computer Vision Library
long_description        opencv is a library that is mainly aimed at real time \
                                        computer vision. Some example areas would be \
                                        Human-Computer Interaction (HCI), Object Identification, \
                                        Segmentation and Recognition, Face Recognition, Gesture \
                                        Recognition, Motion Tracking, Ego Motion, Motion \
                                        Understanding, Structure From Motion (SFM), and Mobile \
                                        Robotics.

homepage                        http://www.intel.com/technology/computing/opencv/
master_sites            sourceforge:opencvlibrary
checksums                       md5 146a05005f2d2c16c4ee10ebd7f1dd58

depends_lib                     port:gtk2 port:zlib port:jpeg \
                                        port:libpng port:tiff

configure.env           CPATH="${prefix}/include"    \
                                        LIBRARY_PATH="${prefix}/lib"
configure.cxxflags-append       "-I${prefix}/include -L${prefix}/lib"

[tobypeterson]

configure.build_arch

[aaron@…]

Replying to toby@…:

configure.build_arch

Okay - so I have the same problem. I am trying to build code-blocks, but it fails because it wants to create x86_64, and the dependency wxWidgets is only i386. So I just want to modify the port, or simply tell macports -- to IGNORE x86_64. I don't even have a 64 bit computer!

So, where do I fiddle with configure.build_arch? Can you point me in the right direction?