I wrote:

> CPPFLAGS=-I/opt/local/include
> CONFIG_SHELL=/bin/bash
> LDFLAGS=-L/opt/local/lib -R/opt/local/lib
> LD_OPTIONS=-L/opt/local/lib -R/opt/local/lib
>
> ../configure --prefix=/opt/local --with-local-prefix=/opt/local
> --enable-languages=c,c++,fortran --with-gmp=/opt/local
> --with-mpfr=/opt/local --with-gnu-as --with-as=/usr/sfw/bin/gas
>
> gmake -j 8 && gmake install (using 8 cores, it builds in a few minutes)

problems with the 64-bit libs:

ldd /opt/local/lib/64/libstdc++.so
libgcc_s.so.1 => /opt/local/lib/libgcc_s.so.1 - wrong ELF class: ELFCLASS32

same for the 64-bit versions of libssp.so, libgomp.so, libgfortran.so

What's the correct way to build gcc so that 32-bit libs are
searched in /opt/local/lib and 64-bit libs in /opt/local/lib/64?