Fix missing support for INTERFACE64 on ARM64 and MIPS64

Author: martin-frbg

cmake/fc.cmake

@@ -6,9 +6,6 @@
 if (${F_COMPILER} STREQUAL "FLANG" AND NOT CMAKE_Fortran_COMPILER_ID STREQUAL "LLVMFlang")
   # This is for classic Flang. LLVM Flang is handled with gfortran below.
   set(CCOMMON_OPT "${CCOMMON_OPT} -DF_INTERFACE_FLANG")
-  if (BINARY64 AND INTERFACE64)
-    set(FCOMMON_OPT "${FCOMMON_OPT} -i8")
-  endif ()
   if (USE_OPENMP)
     set(FCOMMON_OPT "${FCOMMON_OPT} -fopenmp")
   endif ()
@@ -55,6 +52,9 @@ if (${F_COMPILER} STREQUAL "GFORTRAN" OR ${F_COMPILER} STREQUAL "F95" OR CMAKE_F
     if (MIPS64)
       if (BINARY64)
         set(FCOMMON_OPT "${FCOMMON_OPT} -mabi=64")
+        if (INTERFACE64)
+          set(FCOMMON_OPT "${FCOMMON_OPT} -fdefault-integer-8")
+	endif ()
       else ()
         set(FCOMMON_OPT "${FCOMMON_OPT} -mabi=n32")
       endif ()
@@ -83,6 +83,9 @@ if (${F_COMPILER} STREQUAL "GFORTRAN" OR ${F_COMPILER} STREQUAL "F95" OR CMAKE_F
         endif ()
       endif ()
     endif ()
+    if (ARM64 AND INTERFACE64)
+          set(FCOMMON_OPT "${FCOMMON_OPT} -fdefault-integer-8")
+    endif ()
   else ()
     if (BINARY64)
       set(FCOMMON_OPT "${FCOMMON_OPT} -m64")