Intel® Fortran Compiler 18.0 Developer Guide and Reference
The ATTRIBUTES directive option ALLOW_NULL enables a corresponding dummy argument to pass a NULL pointer (defined by a zero or the NULL intrinsic) by value for the argument.
!DIR$ ATTRIBUTES ALLOW_NULL :: arg
arg |
Is the name of the argument. |
ALLOW_NULL is only valid if ATTRIBUTES REFERENCE is also specified; otherwise, it has no effect.