Sun Studio 12 Update 1: Fortran User's Guide

3.4.9 –copyargs

Allow assignment to constant arguments.

Allow a subprogram to change a dummy argument that is a constant. This option is provided only to allow legacy code to compile and execute without a runtime error.

Code that aborts unless compiled with -copyargs is, of course, not Fortran standard compliant. Also, such code is often unpredictable.