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(g77-295.info)Fortran Dialect Options
Options Controlling Fortran Dialect
===================================
The following options control the dialect of Fortran that the
compiler accepts:
`-ffree-form'
`-fno-fixed-form'
Specify that the source file is written in free form (introduced
in Fortran 90) instead of the more-traditional fixed form.
`-ff90'
Allow certain Fortran-90 constructs.
This option controls whether certain Fortran 90 constructs are
recognized. (Other Fortran 90 constructs might or might not be
recognized depending on other options such as `-fvxt',
`-ff90-intrinsics-enable', and the current level of support for
Fortran 90.)
Note: Fortran 90, for more information.
`-fvxt'
Specify the treatment of certain constructs that have different
meanings depending on whether the code is written in GNU Fortran
(based on FORTRAN 77 and akin to Fortran 90) or VXT Fortran (more
like VAX FORTRAN).
The default is `-fno-vxt'. `-fvxt' specifies that the VXT Fortran
interpretations for those constructs are to be chosen.
Note: VXT Fortran, for more information.
`-fdollar-ok'
Allow `$' as a valid character in a symbol name.
`-fno-backslash'
Specify that `\' is not to be specially interpreted in character
and Hollerith constants a la C and many UNIX Fortran compilers.
For example, with `-fbackslash' in effect, `A\nB' specifies three
characters, with the second one being newline. With
`-fno-backslash', it specifies four characters, `A', `\', `n', and
`B'.
Note that `g77' implements a fairly general form of backslash
processing that is incompatible with the narrower forms supported
by some other compilers. For example, `'A\003B'' is a
three-character string in `g77', whereas other compilers that
support backslash might not support the three-octal-digit form,
and thus treat that string as longer than three characters.
Note: Backslash in Constants, for information on why
`-fbackslash' is the default instead of `-fno-backslash'.
`-fno-ugly-args'
Disallow passing Hollerith and typeless constants as actual
arguments (for example, `CALL FOO(4HABCD)').
Note: Ugly Implicit Argument Conversion, for more information.
`-fugly-assign'
Use the same storage for a given variable regardless of whether it
is used to hold an assigned-statement label (as in `ASSIGN 10 TO
I') or used to hold numeric data (as in `I = 3').
Note: Ugly Assigned Labels, for more information.
`-fugly-assumed'
Assume any dummy array with a final dimension specified as `1' is
really an assumed-size array, as if `*' had been specified for the
final dimension instead of `1'.
For example, `DIMENSION X(1)' is treated as if it had read
`DIMENSION X(*)'.
Note: Ugly Assumed-Size Arrays, for more information.
`-fugly-comma'
In an external-procedure invocation, treat a trailing comma in the
argument list as specification of a trailing null argument, and
treat an empty argument list as specification of a single null
argument.
For example, `CALL FOO(,)' is treated as `CALL FOO(%VAL(0),
%VAL(0))'. That is, *two* null arguments are specified by the
procedure call when `-fugly-comma' is in force. And `F = FUNC()'
is treated as `F = FUNC(%VAL(0))'.
The default behavior, `-fno-ugly-comma', is to ignore a single
trailing comma in an argument list. So, by default, `CALL
FOO(X,)' is treated exactly the same as `CALL FOO(X)'.
Note: Ugly Null Arguments, for more information.
`-fugly-complex'
Do not complain about `REAL(EXPR)' or `AIMAG(EXPR)' when EXPR is a
`COMPLEX' type other than `COMPLEX(KIND=1)'--usually this is used
to permit `COMPLEX(KIND=2)' (`DOUBLE COMPLEX') operands.
The `-ff90' option controls the interpretation of this construct.
Note: Ugly Complex Part Extraction, for more information.
`-fno-ugly-init'
Disallow use of Hollerith and typeless constants as initial values
(in `PARAMETER' and `DATA' statements), and use of character
constants to initialize numeric types and vice versa.
For example, `DATA I/'F'/, CHRVAR/65/, J/4HABCD/' is disallowed by
`-fno-ugly-init'.
Note: Ugly Conversion of Initializers, for more information.
`-fugly-logint'
Treat `INTEGER' and `LOGICAL' variables and expressions as
potential stand-ins for each other.
For example, automatic conversion between `INTEGER' and `LOGICAL'
is enabled, for many contexts, via this option.
Note: Ugly Integer Conversions, for more information.
`-fonetrip'
Executable iterative `DO' loops are to be executed at least once
each time they are reached.
ANSI FORTRAN 77 and more recent versions of the Fortran standard
specify that the body of an iterative `DO' loop is not executed if
the number of iterations calculated from the parameters of the
loop is less than 1. (For example, `DO 10 I = 1, 0'.) Such a
loop is called a "zero-trip loop".
Prior to ANSI FORTRAN 77, many compilers implemented `DO' loops
such that the body of a loop would be executed at least once, even
if the iteration count was zero. Fortran code written assuming
this behavior is said to require "one-trip loops". For example,
some code written to the FORTRAN 66 standard expects this behavior
from its `DO' loops, although that standard did not specify this
behavior.
The `-fonetrip' option specifies that the source file(s) being
compiled require one-trip loops.
This option affects only those loops specified by the (iterative)
`DO' statement and by implied-`DO' lists in I/O statements. Loops
specified by implied-`DO' lists in `DATA' and specification
(non-executable) statements are not affected.
`-ftypeless-boz'
Specifies that prefix-radix non-decimal constants, such as
`Z'ABCD'', are typeless instead of `INTEGER(KIND=1)'.
You can test for yourself whether a particular compiler treats the
prefix form as `INTEGER(KIND=1)' or typeless by running the
following program:
EQUIVALENCE (I, R)
R = Z'ABCD1234'
J = Z'ABCD1234'
IF (J .EQ. I) PRINT *, 'Prefix form is TYPELESS'
IF (J .NE. I) PRINT *, 'Prefix form is INTEGER'
END
Reports indicate that many compilers process this form as
`INTEGER(KIND=1)', though a few as typeless, and at least one
based on a command-line option specifying some kind of
compatibility.
`-fintrin-case-initcap'
`-fintrin-case-upper'
`-fintrin-case-lower'
`-fintrin-case-any'
Specify expected case for intrinsic names. `-fintrin-case-lower'
is the default.
`-fmatch-case-initcap'
`-fmatch-case-upper'
`-fmatch-case-lower'
`-fmatch-case-any'
Specify expected case for keywords. `-fmatch-case-lower' is the
default.
`-fsource-case-upper'
`-fsource-case-lower'
`-fsource-case-preserve'
Specify whether source text other than character and Hollerith
constants is to be translated to uppercase, to lowercase, or
preserved as is. `-fsource-case-lower' is the default.
`-fsymbol-case-initcap'
`-fsymbol-case-upper'
`-fsymbol-case-lower'
`-fsymbol-case-any'
Specify valid cases for user-defined symbol names.
`-fsymbol-case-any' is the default.
`-fcase-strict-upper'
Same as `-fintrin-case-upper -fmatch-case-upper
-fsource-case-preserve -fsymbol-case-upper'. (Requires all
pertinent source to be in uppercase.)
`-fcase-strict-lower'
Same as `-fintrin-case-lower -fmatch-case-lower
-fsource-case-preserve -fsymbol-case-lower'. (Requires all
pertinent source to be in lowercase.)
`-fcase-initcap'
Same as `-fintrin-case-initcap -fmatch-case-initcap
-fsource-case-preserve -fsymbol-case-initcap'. (Requires all
pertinent source to be in initial capitals, as in `Print
*,SqRt(Value)'.)
`-fcase-upper'
Same as `-fintrin-case-any -fmatch-case-any -fsource-case-upper
-fsymbol-case-any'. (Maps all pertinent source to uppercase.)
`-fcase-lower'
Same as `-fintrin-case-any -fmatch-case-any -fsource-case-lower
-fsymbol-case-any'. (Maps all pertinent source to lowercase.)
`-fcase-preserve'
Same as `-fintrin-case-any -fmatch-case-any -fsource-case-preserve
-fsymbol-case-any'. (Preserves all case in user-defined symbols,
while allowing any-case matching of intrinsics and keywords. For
example, `call Foo(i,I)' would pass two *different* variables
named `i' and `I' to a procedure named `Foo'.)
`-fbadu77-intrinsics-delete'
`-fbadu77-intrinsics-hide'
`-fbadu77-intrinsics-disable'
`-fbadu77-intrinsics-enable'
Specify status of UNIX intrinsics having inappropriate forms.
`-fbadu77-intrinsics-enable' is the default. Note: Intrinsic
Groups.
`-ff2c-intrinsics-delete'
`-ff2c-intrinsics-hide'
`-ff2c-intrinsics-disable'
`-ff2c-intrinsics-enable'
Specify status of f2c-specific intrinsics.
`-ff2c-intrinsics-enable' is the default. Note: Intrinsic
Groups.
`-ff90-intrinsics-delete'
`-ff90-intrinsics-hide'
`-ff90-intrinsics-disable'
`-ff90-intrinsics-enable'
Specify status of F90-specific intrinsics.
`-ff90-intrinsics-enable' is the default. Note: Intrinsic
Groups.
`-fgnu-intrinsics-delete'
`-fgnu-intrinsics-hide'
`-fgnu-intrinsics-disable'
`-fgnu-intrinsics-enable'
Specify status of Digital's COMPLEX-related intrinsics.
`-fgnu-intrinsics-enable' is the default. Note: Intrinsic
Groups.
`-fmil-intrinsics-delete'
`-fmil-intrinsics-hide'
`-fmil-intrinsics-disable'
`-fmil-intrinsics-enable'
Specify status of MIL-STD-1753-specific intrinsics.
`-fmil-intrinsics-enable' is the default. Note: Intrinsic
Groups.
`-funix-intrinsics-delete'
`-funix-intrinsics-hide'
`-funix-intrinsics-disable'
`-funix-intrinsics-enable'
Specify status of UNIX intrinsics. `-funix-intrinsics-enable' is
the default. Note: Intrinsic Groups.
`-fvxt-intrinsics-delete'
`-fvxt-intrinsics-hide'
`-fvxt-intrinsics-disable'
`-fvxt-intrinsics-enable'
Specify status of VXT intrinsics. `-fvxt-intrinsics-enable' is
the default. Note: Intrinsic Groups.
`-ffixed-line-length-N'
Set column after which characters are ignored in typical fixed-form
lines in the source file, and through which spaces are assumed (as
if padded to that length) after the ends of short fixed-form lines.
Popular values for N include 72 (the standard and the default), 80
(card image), and 132 (corresponds to "extended-source" options in
some popular compilers). N may be `none', meaning that the entire
line is meaningful and that continued character constants never
have implicit spaces appended to them to fill out the line.
`-ffixed-line-length-0' means the same thing as
`-ffixed-line-length-none'.
Note: Source Form, for more information.
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