Installation issue with GMP 5.0.2

[Frank Thorne <thornef@mailbox.sc.edu>]

Hello all, I am trying to install PARI/GP with GMP (so I can use Karim 
Belabas's cubic package) -- so far without success.

I am running Mac OS Version 10.5.8. I just freshly installed GMP version 
5.0.2 using MacPorts and "sudo port install gmp" and it seems to have 
installed fine.

I next tried to reinstall Pari/GP 2.5.1 (make clean and then ./Configure). 
The following is from the output:

...Found libgmp in /usr/local/lib
...Found gmp header in /opt/local/include
### Your version of GMP is too old for PARI. Please upgrade
### Building without GNU MP support

I looked at /opt/local/include/gmp.h and verified that it specifies 
Version 5.0.2.

Is this version really to old for PARI? This seems implausible, as the 
latest version is only 5.0.4.

However, I also tried uninstalling 5.0.2 using MacPorts, and installing 
GMP 5.0.4 manually. When I did this I got the following error (on "make 
install"):

ld: duplicate symbol ___gmpz_abs in .libs/compat.o and .libs/assert.o
collect2: ld returned 1 exit status
make[2]: *** [libgmp.la] Error 1
make[1]: *** [install-recursive] Error 1
make: *** [install] Error 2

I tried first using the command

C=gcc-4.2 CXX=g++4.2 ./configure

as suggested here

http://gmplib.org/list-archives/gmp-bugs/2010-January/001838.html

however that produced the different error (on typing the command above 
in).

configure: error: in `/Users/frankthorne/Downloads/gmp-5.0.4':
configure: error: C++ preprocessor "/lib/cpp" fails sanity check
See `config.log' for more details.

A request for help to the gmplib was not as helpful as I was hoping (some 
people suggested I upgrade my OS; this seems like a hassle but if people 
think it will help I would be happy to try it).

Does anyone understand what produces any of these errors, and can anyone 
recommend a way to install PARI/GP with GMP? I should mention that I know 
basically nothing about C development or Unix/Linux administration, have 
tried everything I could find, and am basically at my wit's end.

THANK YOU VERY MUCH.

Regards,
Frank Thorne