https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67068
--- Comment #3 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Thu, Jul 30, 2015 at 06:24:19PM +0000, mwglass at sandia dot gov wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67068 > > --- Comment #2 from Mike Glass <mwglass at sandia dot gov> --- > Yes, all the FORTRAN code is compiled with those options. We want to mimic the > behavior of the Intel compiler when we add the '-r8' flag to their compiler: > > Makes default real and complex declarations, constants, functions, and > intrinsics 8 bytes long. REAL declarations are treated as DOUBLE PRECISION > (REAL(KIND=8)) and COMPLEX declarations are treated as DOUBLE COMPLEX > (COMPLEX(KIND=8)). Real and complex constants of unspecified KIND are > evaluated > in double precision (KIND=8). > You should only need -freal-4-real-8. If your code uses COMMON or EQUIVALENCE, you may also want to use -finteger-4-integer-8 In addition, it is advisable to never mix the -fdefault-* and -freal-* options. These do different things internally, and may in fact cause conflicts.