https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118259
--- Comment #4 from mjr19 at cam dot ac.uk --- Add using seed=iand(seed*int(1103515245,selected_int_kind(18))+12345,z'7fffffff') also works as expected. Converting the code to C shows the same behaviour as the Fortran if seed is a static int (overflows on ints are also undefined in C), whereas using a static unsigned int (for which overflows are defined) gives the same result at -O3 as at other optimisation levels, and the results I had expected, but not actually been entitled to. Thanks for pointing out the consequences of my sloppy Fortran.
