Cactus Code Thorn TestFpointerNULL
Author(s)    : Thomas Radke
Maintainer(s): Cactus team
Licence      : LGPL
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1. Purpose

This thorn tests whether a Fortran routine accepts a NULL pointer reference
as a function argument when called from a C function. The code should not crash
as long as the NULL pointer argument isn't dereferenced.

Currently this mechanism is used by the Cactus scheduler bindings C functions
which pass unallocated grid variables as NULL pointers to a scheduled Fortran
routine. Cactus makes the assumption here that those NULL pointers are legal
function arguments.

Once we find out that this basic assumption is no longer true we have a problem.
So always run this thorn's testsuite on a new platform / with a new fortran
compiler !