Select FORTRAN 77 compatibility mode.
This option flag enables porting legacy FORTRAN 77 source programs, including those with language extensions accepted by the Sun WorkShop f77 compiler, to the f95 Fortran compiler. (There is no longer a separate FORTRAN 77 compiler.)
list is a comma-separated list selected from the following possible keywords:
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All keywords can be prefixed by no% to disable the feature, as in:
-f77=%all,no%backslash
The default, when -f77 is not specified, is -f77=%none. Using -f77 without a list is equivalent to specifying -f77=%all.
Exceptions Trapping and -f77:
Specifying -f77 does not change the Fortran trapping mode, which is -ftrap=common. f95 differs from the Fortran 77 compiler’s behavior regarding arithmetic exception trapping. The Fortran 77 compiler allowed execution to continue after an arithmetic exception occurred. Compiling with -f77 also causes the program to call ieee_retrospective on program exit to report on any arithmetic exceptions that might have occurred. Specify -ftrap=%none following the -f77 option flag on the command line to mimic the original Fortran 77 behavior.
See Mixing Languages for complete information on f77 compatibility and Fortran 77 to Fortran 95 migration.
See also the -xalias flag for handling non-standard programming syndromes that may cause incorrect results.