I've been having trouble getting PVM 3.4.5 to install under MacPorts on Leopard. The
conf/DARWIN.def configuration file defines the
FAKEXDRFLOAT preprocessor symbol; it may be needed for OS X 10.4, but it causes a compiler error w. GCC 4.0.1 under 10.5:
../../src/pmsg.c:785: error: static declaration of 'xdr_float' follows non-static declaration.
The workaround is simple: install the Darwin8 variant.
$ sudo port install pvm +darwin_8