Table of Contents
Previous: -f77
Option: f90
-f90=list
This setting provides detailed control
over the warnings about supported extensions to the Fortran 77 Standard
that were not adopted as part of the Fortran 90 Standard. Note that ftnchek
does not support the full Fortran 90 language. However, it does support
some common extensions to Fortran 77 that were prevalent before Fortran
90 was defined. Some of these extensions became part of the Fortran 90
Standard, but others did not. The -f90 setting warns only about the latter.
That is, this flag covers things that are neither legal Fortran 77 nor
legal Fortran 90. Therefore, the warnings controlled by this flag are
basically a subset of the warnings controlled by -f77 . There are a few
cases, described below, where the circumstances in which the warning is
given are slightly different for the two flags.
The list consists of
keywords separated by commas or colons. There are three special keywords:
all to turn on all the warnings about nonstandard extensions, none to
turn them all off, and help to print the list of all the keywords with
a brief explanation of each. If list is omitted, -f90 is equivalent to
-f90=all , and -nof90 is equivalent to -f90=none .
The following keywords
have identical meanings for -f90 as for -f77 . The reader is referred to
the explanations under -f77 .
accept-type | double-complex | param-noparen
|
backslash | format-dollarsign | pointer |
byte | format-edit-descr
| quad-constant |
cpp | function-noparen | type-size |
d-comment | name-dollarsign
| variable-format |
dec-tab | param-implicit-type | vms-io |
The keywords
which differ somewhat from the corresponding -f77 keywords are as follows.
- continuation:
- The limit on the number of continuation lines for a statement
in fixed source form is the same, namely 19, in Fortran 90 as in Fortran
77. For free source form the limit is 39 continuation lines, and a line
containing a continuation mark cannot be otherwise empty or contain only
a comment.
- intrinsic:
- This is the same as for -f77 except for the intrinsic
functions defined in MIL-STD 1753, which are all included in Fortran 90,
and so are not warned about. (See -intrinsic for a list.)
- io-keywords:
- This is the same as for -f77 except that no warnings are given for the
I/O keywords that are standard in Fortran 90.
- long-line:
- Although the Fortran
90 Standard allows lines longer than 72 characters in free source form,
this restriction still applies to fixed source form. In free source form
the line length limit is 132 characters, and unlike fixed form, ftnchek
does not allow this limit to be increased.
- mixed-expr:
- This is the same
as for -f77 except for expressions mixing extended precision real with
complex data types, which are permitted in Fortran 90.
- statement-order:
- This is similar to the corresponding -f77 warning, but applies the somewhat
looser restrictions on statement order of the Fortran 90 Standard. In
particular, Fortran 90 allows DATA statements and statement-function definitions
to be intermixed with specification statements.
- typeless-constant:
- In Fortran
90, binary, octal, and hexadecimal constants of the form B'ddd' , O'ddd' ,
and Z'ddd' , respectively, are permitted. Here 'ddd' represents a string
of digits. ftnchek recognizes these forms, as well as a variant of the
form X'ddd' for a hexadecimal constant, and other variants in which the
base indicator B , O , Z , or X follows the digit string. These variants
were not adopted in Fortran 90, so only they are warned about when this
flag is turned on.
See also: -f77 , -f95 , -portability , -pretty , -wordsize
.
Next: -f95