compiling on sco

we're attempting to compile postgres on a box running open server 5 using
sco's development tools and gnu's make (gmake). somewhere in the make it
came back with the following lines from which we can't discern the
errors? can anyone help point this out? or is sco a hopeless cause?
(it's 7.0.3 that's being installed for compatibility reasons)

tia.

gmake[3]: Leaving directory
`/devel/src/postgres/postgresql-7.0.3/src/interfaces/ecpg/lib'
gmake -C preproc all
gmake[3]: Entering directory
`/devel/src/postgres/postgresql-7.0.3/src/interfaces/ecpg/preproc'
cc -b
elf -I../../../include -I../../../backend -dy -I../include -DMAJOR_VERSIO
N=2 -DMINOR_VERSION=7 -DPATCHLEVEL=1 -DINCLUDE_PATH=\"/usr/local/pgsql/inclu
de\" -c -o preproc.o preproc.c
(EOF):internal error:evalexpr():inappropriate expr type: 0
gmake[3]: *** [preproc.o] Error 1
gmake[3]: Leaving directory
`/devel/src/postgres/postgresql-7.0.3/src/interfaces/ecpg/preproc'
gmake[2]: *** [all] Error 2
gmake[2]: Leaving directory
`/devel/src/postgres/postgresql-7.0.3/src/interfaces/ecpg'
gmake[1]: *** [all] Error 2
gmake[1]: Leaving directory
`/devel/src/postgres/postgresql-7.0.3/src/interfaces'
gmake: *** [all] Error 2
$