ftnchek - Online in the Cloud

PROGRAM:

NAME

ftnchek - Fortran 77 program checker

SYNOPSIS

ftnchek [ -arguments[=list] ] [ -array[=list] ]
[ -[no]brief ] [ -calltree[=list] ] [ -[no]check ]
[ -columns[=num] ] [ -common[=list] ]
[ -[no]crossref[=list] ] [ -[no]declare ]
[ -[no]division ] [ -errors[=num] ] [ -[no]extern ]
[ -[no]f77[=list] ] [ -[no]f90[=list] ]
[ -[no]f95[=list] ] [ -[no]help ]
[ -[no]identifier-chars[=list] ] [ -include=str ]
[ -intrinsic[=list] ] [ -[no]library ] [ -[no]list ]
[ -makedcls[=list] ] [ -mkhtml[=list] ]
[ -[no]novice ] [ -output=str ]
[ -pointersize[=num] ] [ -[no]portability[=list] ]
[ -[no]pretty[=list] ] [ -project[=list] ]
[ -[no]pure ] [ -[no]quiet ] [ -[no]reference ]
[ -[no]resources ] [ -[no]sixchar ] [ -[no]sort ]
[ -source[=list] ] [ -style[=list] ] [ -[no]symtab ]
[ -[no]truncation[=list] ] [ -usage[=list] ]
[ -[no]vcg ] [ -[no]version ] [ -[no]volatile ]
[ -wordsize[=num] ] [ -wrap[=num] ] [ files ... ]

DESCRIPTION

ftnchek (short for Fortran checker) is designed to detect certain errors in a Fortran
program that a compiler usually does not. ftnchek is not primarily intended to detect
syntax errors. Its purpose is to assist the user in finding semantic errors. Semantic
errors are legal in the Fortran language but are wasteful or may cause incorrect
operation. For example, variables which are never used may indicate some omission in the
program; uninitialized variables contain garbage which may cause incorrect results to be
calculated; and variables which are not declared may not have the intended type. ftnchek
is intended to assist users in the debugging of their Fortran program. It is not intended
to catch all syntax errors. This is the function of the compiler. Prior to using
ftnchek, the user should verify that the program compiles correctly.

This document first summarizes how to invoke ftnchek. That section should be read before
beginning to use ftnchek. Later sections describe ftnchek's options in more detail, give
an example of its use, and explain how to interpret the output. The final sections
mention the limitations and known bugs in ftnchek.

INVOKING FTNCHEK

ftnchek is invoked through a command of the form:

$ ftnchek [-option -option ...] filename [filename ...]

The brackets indicate something which is optional. The brackets themselves are not
actually typed. Here options are command-line switches or settings, which control the
operation of the program and the amount of information that will be printed out. If no
option is specified, the default action is to print error messages, warnings, and
informational messages, but not the program listing or symbol tables.

Each option begins with the '-' character. (On VAX/VMS or MS-DOS systems you may use
either '/' or '-'.) For the sake of conformity with an increasingly common convention,
options can also begin with '--'. The options are described at greater length in the next
section.

ftnchek options fall into two categories: switches, which are either true or false, and
settings, which have a numeric or string value. The name of a switch is prefixed by 'no'
or 'no-' to turn it off: e.g. -nopure would turn off the warnings about impure functions.
The 'no' prefix can also be used with numeric settings, having the effect of turning off
the corresponding warnings. Settings that control lists of warnings have a special syntax
discussed below. Only the first 3 characters of an option name (not counting the '-')
need be provided. A colon may be used in place of an equals sign for numeric or string
setting assignments; however, we show only the equals sign form below.

The switches and settings which ftnchek currently recognizes are listed below. For each
option, the default is the value used if the option is not explicitly specified, while the
turn-on is the value used if the option is given without assigning it a value.

-arguments=list
Control warnings about subprogram type and argument mismatches. Default = turn-on
= all.

-array=list
Control warnings in checking array arguments of subprograms. Default = turn-on =
all.

-brief Use shorter format for some error messages. Default = no.

-calltree=list
Produce subprogram call hierarchy in one of 3 formats: text call-tree, who-calls-
who and VCG. Default = none, turn-on = tree,prune,sort.

If the -mkhtml option is invoked and tree is the applied calltree option, a file
named CallTree.html, will be produced depicting the tree in HTML format.

-check Perform checking. Default = yes.

-columns=num
Set maximum line length to num columns. (Beyond this is ignored.) Turn-on = max =
132. Default = 72.

-common=list
Set degree of strictness in checking COMMON blocks. Default = turn-on = all.

-crossref=list
Print cross-reference list of subprogram calls, label usage, and/or COMMON block
use. Default = none.

-declare
Print a list of all identifiers whose datatype is not explicitly declared. Default
= no.

-division
Warn wherever division is done (except division by a constant). Default = no.

-errors=num
Set the maximum number of error messages per cascade. Default = turn-on = 3.

-extern
Warn if external subprograms which are invoked are never defined. Default = yes.

-f77=list
Control specific warnings about supported extensions to the Fortran 77 Standard.
Default = none, turn-on = all.

-f90=list
Control specific warnings about supported extensions to the Fortran 77 Standard
that were not adopted as part of the Fortran 90 Standard. Default = none, turn-on
= all.

-f95=list
Control specific warnings about standard Fortran 77 features that were deleted from
the Fortran 95 Standard. Default = none, turn-on = all.

-help Print command summary. Default = no.

-identifier-chars=list
Define non-alphanumeric characters that may be used in identifiers. Default =
turn-on = dollar sign and underscore.

-include=path
Define a directory to search for INCLUDE files before searching in the system-wide
directory. Cumulative. Default = turn-on = none.

-intrinsic=list
Control treatment of nonstandard intrinsic functions. Default = all except vms for
Unix version, all except unix for VMS version, all except unix and vms for other
versions. Turn-on = all.

-library
Begin library mode: do not warn about subprograms in file that are defined but
never used. Default = no.

-list Print source listing of program. Default = no.

-makedcls=list
Prepare a file of declarations. The list specifies options for the format of this
file. Default = none, turn-on = declarations.

-mkhtml=list
Create individual HTML document files from ftnchek analysis and code comments.
Usually you will also want to specify -call=tree to create the root HTML file
CallTree.html. Default = none, turn-on = documents.

-novice
Give output suitable for novice users. Default = yes.

-output=filename
Send output to the given file. Default and turn-on sends output to the screen.
(Default filename extension is .lis).

-pointersize=num
Set the size of ``Cray pointer'' variables to num bytes. Min = 1, max = 16.
Default = turn-on = 4

-portability=list
Warn about non-portable usages. Default = none, turn-on = all.

-pretty=list
Give warnings for possibly misleading appearance of source code. Default = turn-
on = all.

-project=list
Create project file (see explanation below). Default = no.

-pure Assume functions are pure, i.e. have no side effects. Default = yes.

-quiet Produce less verbose output. Default = no.

-reference
Print table of subprograms referenced by each subprogram. Default = no.

-resources
Print amount of resources used in analyzing the program. Default = no.

-sixchar
List any variable names which clash at 6 characters length. Default = no.

-sort Print list of subprograms sorted in prerequisite order. Default = no.

-source=list
Select source formatting options: fixed or free form, DEC Fortran tab-formatted
lines, VMS-style INCLUDE statement, UNIX-style backslash escape sequences, and
implicit typing of parameters. Default = none, turn-on = all.

-style=list
Produce extra-picky warnings about obsolescent or old-fashioned programming
constructions. Default = none, turn-on = all.

-symtab
Print symbol table and label table for each subprogram. Default = no.

-truncation=list
Check for possible loss of accuracy by truncation. Default = turn-on = all.

-usage=list
Control warnings about unused or uninitialized variables, common blocks, etc.
Default = turn-on = all.

-vcg Produce VCG format of call graph.

-version
Print version number. Default = no.

-volatile
Assume COMMON blocks lose definition between activations. Default = no. (Obsolete.
Use -common=volatile instead.)

-wordsize=num
Set the default word size for numeric quantities to num bytes. Default = turn-on =
4 bytes.

-wrap=num
Set output column at which to wrap long error messages and warnings to the next
line. If set to 0, turn off wrapping. Default = turn-on = 79.

When more than one option is used, they should be separated by a blank space, except on
systems such as VMS where options begin with slash ( / ). No blank spaces may be placed
around the equals sign ( = ) in a setting. ftnchek "?" will produce a command summary
listing all options and settings.

For settings that take a list of keywords, namely -arguments, -array, -calltree, -common,
-crossref, -f77, -f90, -f95, -intrinsic, -makedcls, -mkhtml, -portability, -pretty,
-project, -source, -style, -truncation, and -usage, the list consists of keywords
separated by commas or colons. If the list of keywords is omitted, the effect is to set
the option to its turn-on value (same as ``all'' in most cases). Also, if the list is
omitted, the setting name can be prefixed with no or no- to turn off all the options it
controls. For example, -f77 turns on all warnings about nonstandard constructions, while
-nof77 turns them all off. Three special keywords are:

help Print out all the option keywords controlled by the setting, with a brief
explanation of their meanings. This keyword cannot be given in a list with other
keywords.

all Set all options. This turns on all options controlled by the setting.

none Clear all options. This turns off all options controlled by the setting.

These three special keywords must be given in full. For all other keywords, only as many
letters of the keyword as are necessary to identify it unambiguously need be given, or a
wildcard pattern may be used. Including a keyword in the list turns the corresponding
option on. For example, -f77=intrinsic would turn on only the warnings about use of
nonstandard intrinsic functions. Prefixing a keyword by no- turns its option off. For
example, -pretty=no-long-line turns off warnings about lines exceeding 72 columns in
length while leaving all other warnings about misleading appearance in effect. If a
setting has default none, you can turn on all options except one or two by using all
first. For example, -f77=all,no-include enables warnings about all nonstandard extensions
except INCLUDE statements. If a setting has default all, you can turn off all warnings
except one or two by using none first. For example, -truncation=none,demotion would turn
off all precision related warnings except about demotions. Wildcard patterns contain an
asterisk to stand for any string of characters. If a wildcard pattern is used, all the
warnings that match it are affected. If no- is prefixed to the pattern, all the matching
warnings are turned off, otherwise they are all turned on. The minimum unambiguous length
rule does not apply to wildcard matching. For example, use -usage=no-*var* to turn off
all warnings relating to variable usage (both local and common). (Unix users may need to
quote any options containing wildcards in order to prevent the shell from attempting to
expand them.) Wildcards are recognized only in lists of warning keywords, not in the top-
level options themselves.

When ftnchek starts up, it looks for environment variables and also for a preferences
file. Any options defined in the environment or in the preferences file are used as
defaults in place of the built-in defaults. They are over-ridden by any command line
options. See the section on changing the defaults for details about the environment
options and the preferences file.

When giving a name of an input file, the extension is optional. If no extension is given,
ftnchek will first look for a project file with extension .prj, and will use that if it
exists. If not, then ftnchek will look for a Fortran source file with the extension .for
for VMS systems, .f for UNIX systems. More than one file name can be given to ftnchek,
and it will process the modules in all files as if they were in a single file.

Wildcards are allowed in the specification of filenames on the command line for the VMS
and MS-DOS versions, as also of course under UNIX and any other system that performs
wildcard expansion in the command processor.

If no filename is given, ftnchek will read input from the standard input.

OPTIONS

This section provides a more detailed discussion of ftnchek command-line options. Options
and filenames may be interspersed on a command line. Most options are positional: each
option remains in effect from the point it is encountered until it is overridden by a
later change. Thus for example, the listing may be suppressed for some files and not for
others. Exceptions are: the -intrinsic, -pointersize, and -wordsize settings, which
cannot be changed once processing of input files has started; the -arguments, -array,
-calltree, -common, -crossref, -extern, -reference, -resources, -sort, -vcg, and -volatile
options, where the action depends only on the value of the option after the processing of
input files is finished; and the -include setting, which is cumulative.

The option names in the following list are in alphabetical order.

-arguments=list
Controls warnings about mismatches between actual and dummy subprogram arguments,
and also about mismatches between expected and actual subprogram type. (An actual
argument is an argument passed to the subprogram by the caller; a dummy argument is
an argument received by the subprogram.) By default, all warnings are turned on.

The list consists of keywords separated by commas or colons. Since all these
warnings are on by default, include a keyword prefixed by no- to turn off a
particular warning. There are three special keywords: all to turn on all the
warnings about arguments, 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, -arguments
is equivalent to -arguments=all, and -noarguments is equivalent to -arguments=none.
The warning keywords with their meanings are as follows:

arrayness:
warn about inconsistent use of arguments that are arrays. These warnings can
be further controlled by the -array option.

type:
warn about dummy arguments of a different data type from the actual arguments.

function-type:
warn if the invocation assumes the function's return value is a different type
than it actually is. Also warns if a function is called as a subroutine, or
vice-versa.

number:
warn about invoking a subprogram with a different number of arguments than the
subprogram expects.

For compatibility with previous versions of ftnchek, a numeric form of this
setting is also accepted: the list is replaced by a number from 0 to 3. A value of
0 turns all the warnings off, 1 turns on only number, 2 turns on all except number,
and 3 turns all the warnings on.

This setting does not apply to checking invocations of intrinsic functions or
statement functions, which can only be turned off by the -nocheck option.

See also: -array, -library, -usage.

-array=list
Controls the degree of strictness in checking agreement between actual and dummy
subprogram arguments that are arrays. The warnings controlled by this setting are
for constructions that might legitimately be used by a knowledgeable programmer,
but that often indicate programming errors. By default, all warnings are turned
on.

The list consists of keywords separated by commas or colons. Since all these
warnings are on by default, include a keyword prefixed by no- to turn off a
particular warning. There are three special keywords: all to turn on all the
warnings about array arguments, 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,
-array is equivalent to -array=all, and -noarray is equivalent to -array=none. The
warning keywords with their meanings are as follows:

dimensions:
warn if the arguments differ in their number of dimensions, or if the actual
argument is an array element while the dummy argument is a whole array.

size:
warn if both arguments are arrays, but they differ in number of elements.

For compatibility with previous versions of ftnchek, a numeric form of this
setting is also accepted: the list is replaced by a number from 0 to 3. A value of
0 turns all the warnings off, 1 turns on only dimensions, 2 turns on only size, and
3 turns all the warnings on.

Note: A warning is always given regardless of this setting if the actual argument
is an array while the dummy argument is a scalar variable, or if the actual
argument is a scalar variable or expression while the dummy argument is an array.
These cases are seldom intentional. (To turn off even these warnings, use
-arguments=no-arrayness.) No warning is ever given if the actual argument is an
array element while the dummy argument is a scalar variable. Variable-dimensioned
arrays and arrays dimensioned with 1 or asterisk match any number of array
elements. There is no check of whether multi-dimensional arrays agree in the size
of each dimension separately.

See also: -arguments, -library, -usage.

-brief
Selects a shorter format for some warning messages. At present, the only warnings
controlled by this flag are those that are printed at the end of processing each
subprogram. These include warnings about variables that are set but not used or
used before set, variable names that do not conform to the Fortran 77 standard,
etc. (These warnings may be suppressed entirely depending on other flags, such as
the -usage or -f77 flags.) In the default format each variable is listed on a
separate line, along with the line number where the variable is declared, set or
used, according to the nature of the warning. The briefer format simply lists all
variables to which the warning applies, with up to 4 variables per line.

See also: -quiet.

-calltree=list
Causes ftnchek to print out the call structure of the complete program.

The list consists of keywords separated by commas or colons. There are two special
keywords: none to turn off all the options, and help to print the list of all the
keywords with a brief explanation of each. (The keyword all turns on all the
options, but should not normally be used since only one format should be
specified.) If list is omitted, -calltree is equivalent to -calltree=tree, and
-nocalltree is equivalent to -calltree=none. By default no call graph is printed.

If the -mkhtml option is invoked and tree is the applied calltree option, a file
named CallTree.html, will also be produced depicting the tree in HTML format. This
file is useful as a starting point for browsing the HTML files describing each
component of the program.

The keywords which control which format is used are as follows:

tree:
produce the call graph in tree format.

reference:
produce the call graph in who-calls-who format (same as -reference switch).

vcg:
produce the call graph in VCG format (same as -vcg switch).

Only one of the formats tree, reference, or vcg may be specified.

The following keywords control options affecting the output:

prune:
prune repeated subtrees (applicable only with tree). This the default.

sort:
sort children of each routine into alphabetical order. This is the default.

See the discussion of the -reference and -vcg flags for details about these
formats.

For tree format, The call graph is printed out starting from the main program,
which is listed on the first line at the left margin. Then on the following lines,
each routine called by the main program is listed, indented a few spaces, followed
by the subtree starting at that routine.

In the default mode, if a routine is called by more than one other routine, its
call subtree is printed only the first time it is encountered Later calls give only
the routine name and the notice ``(see above)''. To have the subtree printed for
each occurrence of the routine, use option no-prune.

Note that the call tree will be incomplete if any of the input files are project
files containing more than one module that were created in -library mode. See the
discussion of project files below.

Technical points: Each list of routines called by a given routine is printed in
alphabetical order unless the no-sort option is given. If multiple main programs
are found, the call tree of each is printed separately. If no main program is
found, a report to that effect is printed out, and the call trees of any top-level
non-library routines are printed. This flag only controls the printing of the call
tree: ftnchek constructs the call tree in any case because it is used to determine
which library modules will be cross-checked. See the discussion of the -library
flag.

For compatibility with previous versions of ftnchek, a numeric form of this
setting is also accepted: the list is replaced by a number from 0 to 15. This
number is formed from 1 for tree format, 2 for reference format, or 3 for vcg
format, plus 4 for no-prune, and 8 for no-sort.

See also: -crossref, -library, -reference, -sort, -symtab, -vcg.

-check
This switch is provided so that errors and warning messages can be turned off when
ftnchek is used for purposes other than finding bugs, such as making declarations
or printing the call tree. It is positional, so after turning all checks off,
selected checks can be turned back on. The effect of -nocheck is to put all
switches, numeric settings, and settings controlling lists of warnings to their
turn-off values, as if they had all been specified with the -no prefix. Switches
and settings that specify options and modes of operation, rather than controlling
warnings, are unaffected. These are -columns, -crossref, -include, -intrinsic,
-library, -list, -makedcls, -novice, -output, -pointersize, -project, -quiet,
-reference, -resources, -sort, -source, -symtab, -vcg, -version, -wordsize, and
-wrap. Default = yes.

Parse errors (syntax errors due to unrecognized or malformed statements) are not
suppressed by this switch, since the results may be incorrect if ftnchek has not
parsed the program correctly.

There are some miscellaneous errors and warning messages that are not controlled by
any other switch, and so can be turned off only by this switch. Note that using
-check following -nocheck only has the effect of turning these special warnings
back on, and does not restore all the checks it turned off. These warnings are:

o Module contains no executable statements.

o In free source form, missing space where space is required (e.g. between a
keyword and an identifier) or space present where none is allowed (e.g. within
an identifier).

o Zero or negative length specification in a data type declaration of the form
type*len.

o Invalid operand(s) in an expression.

o Array assigned to scalar.

o Type mismatch between DO index and bounds.

o Undefined common block declared in SAVE statement.

o Intrinsic function explicitly declared with an incompatible type.

o Unknown intrinsic function explicitly declared in an INTRINSIC statement.

o Intrinsic function passed as a subprogram argument is not declared in an
INTRINSIC statement.

o Intrinsic function or statement function invoked incorrectly.

o Function does not set return value prior to RETURN statement.

o Parameter constant value not evaluated (this is ftnchek's fault, and it is just
informing you of the fact).

o Entry point of a subprogram is later used as a different subprogram's name.

o Unknown keyword used in an I/O statement.

o Illegal label reference (e.g. GOTO refers to a non-executable statement; I/O
statement refers to a non-format statement).

See also: -errors.

-columns=num
Set maximum statement length to num columns. (Beyond this is ignored.) This
setting is provided to allow checking of programs which may violate the Fortran
standard limit of 72 columns for the length of a statement. According to the
standard, all characters past column 72 are ignored. If this setting is used when
the -f77=long-line option is in effect, a warning will be given for any lines in
which characters past column 72 are processed. Turn-on = max = 132. Default = 72.

This setting does not suppress warnings about the presence of characters beyond
column 72. To process code with meaningful program text beyond column 72, use this
setting and be sure the -f77 long-line option is off. To process code with
sequence numbers in columns 73 to 80, leave the the columns setting at the default
value and use the -pretty=no-long-line flag.

See also: -f77, -pretty.

-common=list
This setting controls the strictness of checking of COMMON blocks. By default, all
warnings except volatile are turned on.

The list consists of keywords separated by commas or colons. Since most of these
warnings are on by default, include a keyword prefixed by no- to turn off a
particular warning. There are three special keywords: all to turn on all the
warnings, 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, -common is equivalent to
-common=dimensions,exact,length,type, and -nocommon is equivalent to -common=none.
The warning keywords with their meanings are as follows:

dimensions:
corresponding arrays in each declaration of a block must agree in size and
number of dimensions. This option only has an effect when used together with
exact.

exact:
the comparison of two blocks is done variable-by-variable rather than simply
requiring agreement between corresponding storage locations. Use this if all
declarations of a given COMMON block are supposed to be identical, which is a
good programming practice.

length:
warn if different declarations of the same block are not equal in total length.
The Fortran 77 Standard requires each named common block, but not blank common,
to be the same length in all modules of the program.

type:
in each declaration of a given COMMON block, corresponding memory locations
(words or bytes) must agree in data type. If used together with exact, this
will require that corresponding variables agree in data type.

volatile:
Assume that COMMON blocks are volatile.

Many Fortran programmers assume that variables, whether local or in COMMON, are
static, i.e. that once assigned a value, they retain that value permanently until
assigned a different value by the program. However, in fact the Fortran 77
Standard does not require this to be the case. Local variables may become
undefined between activations of a module in which they are declared. Similarly,
COMMON blocks may become undefined if no module in which they are declared is
active. (The technical term for entities with this behavior is ``automatic'', but
ftnchek uses the word ``volatile'' since it is clearer to the nonspecialist.) Only
COMMON blocks declared in a SAVE statement, or declared in the main program or in a
block data subprogram remain defined as long as the program is running. Variables
and COMMON blocks that can become undefined at some point are called volatile.

If the -common=volatile flag is turned on, ftnchek will warn you if it finds a
volatile COMMON block. If, at the same time, the -usage=com-block-volatile option
is turned on (which is the default), ftnchek will try to check whether such a block
can lose its defined status between activations of the modules where it is
declared. ftnchek does not do a very good job of this: the rule used is to see
whether the block is declared in two separated subtrees of the call tree. For
instance, this would be the case if two modules, both called from the main program,
shared a volatile COMMON block. A block can also become undefined between two
successive calls of the same subprogram, but ftnchek is not smart enough to tell
whether a subprogram can be called more than once, so this case is not checked for.

The -common=volatile flag does not affect the way ftnchek checks the usage of local
variables.

For compatibility with previous versions of ftnchek, a numeric form of this
setting is also accepted: the list is replaced by a number from 0 to 3. A value of
0 turns all the warnings off, 1 or greater turns on type, 2 or greater turns on
length, and 3 turns on dimensions and exact also. The numeric form cannot turn on
the volatile option.

See also: -library, -usage.

-crossref=list
Prints cross-reference tables. Default = none.

The list consists of keywords separated by commas or colons. The keywords with
their meanings are as follows:

calls:
table lists each subprogram followed by a list of routines that call it.
This listing omits library modules that are not in the call tree of the main
program. The list is alphabetized.

common:
table lists each COMMON block followed by a list of the routines that access
it. These listed routines are those in which some variables in the COMMON
block are accessed, not simply those routines that declare the block. (To
find out what routines declare a COMMON block but do not use it, see the
-usage flag.)

labels:
table lists each label followed by a list of all references to it. A label
reference is denoted by the line number and statement type of the referring
statement. The label list is in sequential order. The references are
listed in the order they are encountered in the program.

See also: -calltree, -reference, -sort, -symtab, -vcg.

-declare
If this flag is set, all identifiers whose datatype is not declared in each module
will be listed. This flag is useful for helping to find misspelled variable names,
etc. The same listing will be given if the module contains an IMPLICIT NONE
statement. Default = no.

See also: -sixchar, -usage.

-division
This switch is provided to help users spot potential division by zero problems. If
this switch is selected, every division except by a constant will be flagged. (It
is assumed that the user is intelligent enough not to divide by a constant which is
equal to zero!) Default = no.

See also: -portability, -truncation.

-errors=num
Set the maximum number of error messages in a ``cascade''. During checking of
agreement of subprogram arguments, common block declarations, and so forth,
sometimes a single case will generate a long string of warnings. Often this simply
indicates some other cause than a genuine item-by-item mismatch, such as for
example a varible missing from one list. So in such cases ftnchek stops printing
the warnings after the cascade limit is reached, and the trailer ``etc...'' is
printed to indicate that there were more errors not printed. If you think that
these warnings are likely to be genuine, use this setting to see more of them.
Turn-on = default = 3, max = 999. A value of 0 means no limit.

This setting does not set an overall limit on the number of error messages printed,
only the number printed in any one cascade. Most types of warnings and error
messages are not subject to the cascade effect and so are not affected by this
setting. To turn off warnings generally, use the individual warning control
options or the -nocheck option.

See also: -check.

-extern
Causes ftnchek to report whether any subprograms invoked by the program are never
defined. Ordinarily, if ftnchek is being run on a complete program, each
subprogram other than the intrinsic functions should be defined somewhere. Turn
off this switch if you just want to check a subset of files which form part of a
larger complete program. Subprogram arguments will still be checked for
correctness. Default = yes.

The -extern flag is now superseded by the -usage=ext-undefined option. For the
sake of convenience, the -extern flag is retained, so that -noextern is equivalent
to -usage=no-ext-undefined option. The -extern switch may be retired eventually.

See also: -library.

-f77=list
Use this setting to catch language extensions which violate the Fortran 77
Standard. Such extensions may cause your program not to be portable. Examples
include the use of underscores in variable names; variable names longer than six
characters; statement lines longer than 72 characters; and nonstandard statements
such as the DO ... ENDDO structure. ftnchek does not report on the use of
lowercase letters. By default, all warnings are turned off.

This setting provides detailed control over the warnings about supported extensions
to the Fortran 77 Standard. (Further details about the extensions themselves are
given below in the section on Extensions.) 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,
-f77 is equivalent to -f77=all, and -nof77 is equivalent to -f77=none. The warning
keywords with their meanings are as follows:

accept-type:
ACCEPT and TYPE I/O statements.

array-bounds:
Expressions defining array bounds that contain array elements or function
references.

assignment-stmt:
Assignment statements involving arrays. In Fortran 90, an array can be
assigned to another array of compatible shape, or a scalar can be assigned to
an array. Neither of these assignments is permitted in Fortran 77.

A related warning occurs when an array is assigned to a scalar. Since this
is illegal also in Fortran 90, it is always warned about regardless of the
-f77 setting (unless all checking is turned off with the -nocheck flag).

attribute-based-decl:
Type declarations in the new Fortran 90 attribute-based style. This style of
declaration is distinguished by the use of a double colon (::) between the
list of attributes and the list of declared variables. This option also
controls warnings for use of Fortran 90 length or kind specifiers in type
declarations. (Although these specifiers can be used in non-attribute-based
declarations, they are controlled by this option to avoid proliferation of
-f77 options.)

automatic-array:
Local (not dummy) arrays which have variable size. These would correspond to
arrays whose storage would have to be dynamically allocated at run time.

backslash:
Unix backslash escape in strings. This warning will be given only if the
-source=unix-backslash setting is specified to cause the escape
interpretation of backslash..

byte: BYTE data type declaration.

case-construct:
The SELECT CASE construct.

character:
Extensions to the Fortran 77 standard regarding character data. At present,
this only controls warnings about character variables declared with zero or
negative length. In Fortran 77, all character variables must be of positive
length. In Fortran 90, they can be zero length, and declarations that
specify negative lengths are permitted, turning into zero for the declared
length. Note: because negative length specifiers may indicate a programming
error, the warning about them is given even if this option is turned off, and
is suppressed only by the -nocheck flag.

common-subprog-name:
Common block and subprogram having the same name.

construct-name:
Use of a construct-name to label a control statement.

continuation:
More than 19 successive continuation lines.

cpp: Unix C preprocessor directives in the source code.

cray-pointer:
``Cray pointer'' syntax.

cycle-exit:
The CYCLE and EXIT statements.

d-comment:
Debugging comments starting with D in the source code.

dec-tab:
DEC Fortran style tab-formatted source code. This warning will be given only
if the -source=dec-tab setting is specified to cause interpretation of tabs
in this style.

do-enddo:
DO loop extensions: terminal statement label omitted, END DO, and WHILE.

double-complex:
Double precision complex datatype.

format-dollarsign:
Dollar sign control code in FORMAT statements.

format-edit-descr:
Nonstandard edit descriptors in FORMAT statements.

function-noparen:
Function definition without parentheses.

implicit-none:
IMPLICIT NONE statement.

include:
INCLUDE statement.

inline-comment:
Inline comments starting with an exclamation point.

internal-list-io:
List-directed I/O to or from an internal file.

intrinsic:
Nonstandard intrinsic functions.

io-keywords
Nonstandard keywords used in I/O statements. These fall into three groups.
The first group includes keywords that are accepted in Fortran 90:

ACTION PAD READWRITE
ADVANCE POSITION SIZE
DELIM READ WRITE
EOR
The second group comprises the following VMS Fortran keywords:

BLOCKSIZE EXTENDSIZE READONLY
BUFFERCOUNT INITIALSIZE RECORDSIZE
CARRIAGECONTROL MAXREC RECORDTYPE
DEFAULTFILE NAME (in OPEN) SHARED
DISP NOSPANBLOCK TYPE
DISPOSE ORGANIZATION
(The keyword NAME is standard only in the INQUIRE statement.) The third
group consists of the following IBM/MVS keyword:

NUM
This flag also controls a warning about use of ACCESS='APPEND', which is
accepted by some compilers. The value of 'APPEND' is not valid for any I/O
specifier in standard Fortran 77, and in Fortran 90 'APPEND' should be used
as a value of the POSITION specifier, not ACCESS.

long-line:
Statements with meaningful code past 72 columns. This warning is given only
if the -columns setting has been used to increase the statement field width.

long-name:
Identifiers over 6 characters long.

mixed-common:
Mixed character and noncharacter data in COMMON block.

mixed-expr:
Nonstandard type combinations in expressions, for example DOUBLE PRECISION
with COMPLEX, assigning hollerith to integer, logical operations on integers.

name-dollarsign:
Dollar sign used as a character in identifiers.

name-underscore:
Underscore used as a character in identifiers.

namelist:
NAMELIST statement.

param-implicit-type:
Implicit typing of a parameter by the data type of the value assigned. This
warning can only occur if implicit parameter typing has been turned on by the
-source=param-implicit-type option, or if the PARAMETER statement is of the
nonstandard form without parentheses. If this option is turned on, then any
instances where implicit parameter typing occurs will be warned about. If
you want to be warned only in those instances where the implicit data type
differs from the default type, use -portability=param-implicit-type instead.
According to the Fortran 77 standard, the data type of a parameter is given
by the same rules as for a variable, and if necessary a type conversion is
done when the value is assigned.

param-intrinsic:
Intrinsic function or exponentiation by a real used to define the value of a
PARAMETER definition.

param-noparen:
PARAMETER statement without parentheses. The user should be aware that the
semantics of this form of the statement differs from that of the standard
form: in this form, the parameter takes its data type from the value
assigned, rather than having its default data type based on the first letter
of the parameter name. (This form of the PARAMETER statement was introduced
by DEC before the Fortran 77 standard was defined, and should be avoided.)

pointer:
Fortran 90 standard pointer-related syntax, including POINTER, TARGET and
ALLOCATABLE type declarations, ALLOCATE, DEALLOCATE, and NULLIFY statements,
and pointer assignment using =>.

quad-constant:
Quad precision real constants, e.g. of the form 1.23Q4.

quotemark:
Strings delimited by quote marks rather than apostrophes.

relops:
Relational (comparison) operators composed of punctuation, namely: < <= == /=
> >=.

semicolon:
Semicolon used as statement separator.

statement-order:
Statements out of the sequence mandated by the Standard. The allowed
sequence is illustrated in Table 1 in the section on Interpreting the Output.

typeless-constant:
Typeless constants, for example Z'19AF'.

type-size:
Type declarations specifying a size, for example REAL*8.

variable-format:
Variable repeat specification or field size in FORMAT. These are of the form
< expr >.

vms-io:
Obsolete. Now has the same meaning as the io-keywords keyword.

See also: -f90, -f95, -portability, -pretty, -style, -wordsize.

-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 cray-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, -style, -wordsize.

-f95=list
This setting provides detailed control over warnings about standard Fortran 77
features that were deleted from the Fortran 95 Standard. Unlike the -f77 and -f90
settings, these warnings apply to syntax which is legal Fortran 77. However, since
these features have been deleted from the Standard, it is possible that programs
containing them will be unacceptable to some newer compilers.

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, -f95 is equivalent to -f95=all, and
-nof95 is equivalent to -f95=none. The warning keywords with their meanings are as
follows.

real-do:
A DO variable of any real numeric type.

pause:
The PAUSE statement.

assign:
The ASSIGN statement, assigned GOTO, or assigned format.

h-edit:
The H edit descriptor in a format.

There is one other Fortran 77 syntax feature that was deleted in Fortran 95, namely
branching to an ENDIF from outside the IF block. However, ftnchek is unable to
analyze program flow, and so it does not provide a warning for this.

See also: -f77, -f90, -portability, -pretty, -style, -wordsize.

-help
Prints a list of all the command-line options with a short description of each
along with its default value. This command is identical in function to the ``?''
argument, and is provided as a convenience for those systems in which the question
mark has special meaning to the command interpreter. Default = no.

The help listing also prints the version number and patch level of ftnchek and a
copyright notice.

Note: the ``default'' values printed in square brackets in the help listing are,
strictly speaking, not the built-in defaults but the current values after any
environment options and any command-line options preceding the -help option have
been processed.

See also: -novice, -version, and help option of all settings that take a list of
keywords.

-identifier-chars=list
Define non-alphanumeric characters that may be used in identifiers. By default,
ftnchek only accepts the dollar sign and underscore as non-alphanumeric characters
in identifier names. The characters in the list replace whatever set of accepted
non-alphanumeric characters was previously in effect. Thus, if dollar sign or
underscore are not included in the list, they lose their status as acceptable
characters.

This option is provided to enable ftnchek to handle source files containing non-
standard identifer names that may be needed, for example, to access certain
operating system services. See the section on Limitations and Extensions for the
treatment of identifiers containing these characters in implicit typing.

Using -noidentifer-chars turns off acceptance of non-alphanumeric characters
entirely.

See also: -source.

-include=path
Specifies a directory to be searched for files specified by INCLUDE statements.
Unlike other command-line options, this setting is cumulative; that is, if it is
given more than once on the command line, all the directories so specified are
placed on a list that will be searched in the same order as they are given. The
order in which ftnchek searches for a file to be included is: the current
directory; the directory specified by environment variable FTNCHEK_INCLUDE if any;
the directories specified by any -include options; the directory specified by
environment variable INCLUDE; and finally in a standard system-wide directory
(/usr/include for UNIX, SYS$LIBRARY for VMS, and \include for MSDOS).

See also: -f77, -source.

-intrinsic=list
Controls whether ftnchek recognizes certain nonstandard intrinsic functions as
intrinsic. The list consists of keywords separated by commas or colons. Some of
the keywords control whether to recognize certain groups of functions, and other
keywords control the expected syntax for invoking some nonstandard intrinsics.
Include a keyword to turn on recognition of the corresponding set of intrinsics or
to allow the corresponding syntax. Include a keyword prefixed by no- to turn off
that recognition.

There are three special keywords: all turns on recognition of all the nonstandard
intrinsics (listed below) and accepts either syntax for those that have variations.
Use none to turn off recognition of all nonstandard intrinsics except those noted
below. Use help to print the list of all the keywords with a brief explanation of
each. If list is omitted, -intrinsic is equivalent to -intrinsic=all, and
-nointrinsic is equivalent to -intrinsic=none.

The nonstandard intrinsic functions needed to support the nonstandard extended
precision data types (double complex and quad precision) are always recognized.
The intrinsics for the double complex data type are:

CDABS CDSQRT DREAL ZLOG
CDCOS DCMPLX IMAG ZSIN
CDEXP DCONJG ZABS ZSQRT
CDLOG DIMAG ZEXP ZCOS
CDSIN
The intrinsics for the quad precision and quad complex types are:

CQABS QARCOS QEXT QNINT
CQCOS QARSIN QEXTD QPROD
CQEXP QATAN QFLOAT QREAL
CQLOG QATAN2 QIMAG QSIGN
CQSIN QCMPLX QINT QSIN
CQSQRT QCONJG QLOG QSINH
DBLEQ QCOS QLOG10 QSQRT
IQINT QCOSH QMAX1 QTAN
IQNINT QDIM QMIN1 QTANH
QABS QEXP QMOD SNGLQ
The keywords controlling recognition of other nonstandard intrinsic functions are
as follows:

extra:
recognize the following commonly available nonstandard intrinsics (all except
EXIT and LOC are defined in MIL-STD 1753):

BTEST IBCLR IEOR ISHFTC
EXIT IBITS IOR LOC
IAND IBSET ISHFT NOT

unix: recognize these common Unix-specific intrinsic functions:

ABORT GMTIME LTIME SRAND
AND IARGC OR SYSTEM
GETARG IRAND RAND TIME
GETENV LSHIFT RSHIFT XOR

vms: recognize these common VMS-specific intrinsic functions:

DATE IDATE SECNDS TIME

ERRSNS RAN SIZEOF

iargc-no-argument:
specify that IARGC may be invoked with no arguments.

iargc-one-argument:
specify that IARGC may be invoked with one argument.

rand-no-argument:
specify that RAND and IRAND may be invoked with no arguments.

rand-one-argument:
specify that RAND and IRAND may be invoked with one argument.

The no-argument and one-argument keywords work as follows: turning the option on
causes ftnchek to accept the corresponding syntax for invocation of the function,
without excluding the possibility of the alternative syntax. Turning the option
off causes the corresponding syntax not to be accepted. If both options are turned
on at once (the default), then either syntax is accepted. Turning both options off
at once would not be meaningful. These options have no effect if recognition of
Unix intrinsics has been turned off.

Note that this setting does not control whether non-standard warnings are issued
about these functions. It controls whether the functions are assumed to be
intrinsic or not, which determines how their usage is checked. When functions in
any of these sets are included, their invocations will be checked according to the
rules for the intrinsic functions; otherwise they will be checked as normal (user-
written) external functions. The non-standard warnings are controlled by the
-f77=intrinsic option.

The default value of this setting is equivalent to -intrinsic=all followed by
-intrinsic=no-vms for the Unix version, -intrinsic=no-unix for the VMS version, and
-intrinsic=no-unix,no-vms for other versions.

Note: In versions of ftnchek prior to 2.10, the -intrinsic flag took a numeric
argument instead of a list of options. For the sake of users who may have written
scripts invoking ftnchek in this way, the numeric form is still accepted. The
numeric form of the setting consists of three digits. The ones digit selects the
set of intrinsic functions to be supported. The digit 0 selects only Fortran 77
standard intrinsics plus those needed to support the nonstandard extended precision
data types. The digit 1 is equivalent to extra, 2 is equivalent to extra,unix, and
3 is equivalent to extra,vms. The tens digit of this setting controls the syntax
of the RAND intrinsic function, and the hundreds digit controls the syntax of the
IARGC function. For these digits, specify 0 to require invocation with no
argument, 1 to require one argument, and 2 to allow either form.

See also: -f77.

-library
This switch is used when a number of subprograms are contained in a file, but not
all of them are used by the application. Normally, ftnchek warns you if any
subprograms are defined but never used. This switch will suppress these warnings.
Default = no.

This switch also controls which subprogram calls and COMMON block declarations are
checked. If a file is read with the -library flag in effect, the subprogram calls
and COMMON declarations contained in a routine in that file will be checked only if
that routine is in the main program's call tree. On the other hand, if the
-library switch is turned off, then ftnchek checks the calls of every routine by
every other routine, regardless of whether those routines could ever actually be
invoked at run time, and likewise all COMMON block declarations are compared for
agreement.

The difference between this switch and the -usage=no-ext-unused option for
subprograms is that the latter suppresses only the warning about routines being
declared but not used. The -library switch goes further and excludes unused
routines processed while it is in effect from all cross-checking of arguments and
COMMON block declarations as well.

(If there is no main program anywhere in the set of files that ftnchek has read, so
that there is no call tree, then ftnchek will look for any non-library routines
that are not called by any other routine, and use these as substitutes for the main
program in constructing the call tree and deciding what to check. If no such top-
level non-library routines are found, then all inter-module calls and all COMMON
declarations will be checked.)

See also: -arguments, -calltree, -common, -extern, -usage.

-list
Specifies that a listing of the Fortran program is to be printed out with line
numbers. If ftnchek detects an error, the error message follows the program line
with a caret ( ^ ) specifying the location of the error. If no source listing was
requested, ftnchek will still print out any line containing an error, to aid the
user in determining where the error occurred. Default = no.

See also: -output, \fB-symtab, fB-quiet.

-makedcls=list
Prepare a neatly-formatted file of declarations of variables, common blocks, and
namelist lists, for possible merging into the source code. The declarations are
stored in a file of the same name as the source code, but with the extension
changed to .dcl. If no declarations are written to the file, it is deleted to
reduce clutter from empty files.

If input comes from standard input, instead of a named file, then declarations are
written to standard output.

Variables are declared in alphabetical order within each declaration class and
type, with integer variables first, because of their later possible use in array
dimensions.

PARAMETER statements are an exception to the alphabetical order rule, because the
Fortran 77 Standard requires that the expressions defining parameter values refer
only to constants and already-defined parameter names. This forces the original
source file order of such statements to be preserved in the declaration files.

Explicit declaration of all variables is considered good modern programming
practice. By using compiler options to reject undeclared variables, misspelled
variable names (or names extending past column 72) can be caught at compile time.
Explicit declarations also greatly facilitate changing floating-point precision
with filters such as dtoq(1L), dtos(1L), fd2s(1L), fs2d(1L), qtod(1L), and
stod(1L). These programs are capable of changing types of explicit floating-point
type declarations, intrinsic functions, and constants, but because they do not
carry out rigorous lexical and grammatical analysis of the Fortran source code,
they cannot provide modified type declarations for undeclared variables. Default
setting = 0, turn-on = 1.

Various options for the form of the declarations file are controlled by the list,
which consists of keywords separated by commas or colons. There are three special
keywords: all to turn on all the options, 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, -makedcls is equivalent to -makedcls=declarations (i.e. produce the
declarations file using the default options), and -nomakedcls is equivalent to
-makedcls=none.

For compatibility with previous versions of ftnchek, a numeric form of this setting
is also accepted: the list is replaced by a number which is the sum of the numbers
in parentheses beside the keywords in the following list. The warning keywords
with their meanings are as follows:

declarations (1):
Write a declaration file. (This is implied by any of the other options, and
can be omitted if any other options are given.)

undeclared-only (2):
By default, all variables are included in the declaration file. With this
option, include only undeclared variables. This setting is useful if you
want to check for undeclared variables, since Fortran source files with all
variables properly declared will not result in a .dcl file. With this
option, common blocks and namelist lists will not be included in the
declaration file, since by their nature they cannot be undeclared.

compact (4):
The declarations are normally prettyprinted to line up neatly in common
columns, as in the declaration files output by the Extended PFORT Verifier,
pfort(1L). This option value selects instead compact output, without column
alignment.

use-continuation-lines (8):
Causes continuation lines to be used where permissible. The default is to
begin a new declaration on each line. This option is appropriate to use
together with compact.

keywords-lowercase (16):
Output Fortran keywords in lowercase, instead of the default uppercase.

vars-and-consts-lowercase (32):
Output variables and constants in lowercase, instead of the default
uppercase. Character string constants are not affected by this option.

exclude-sftran3 (64):
Omit declarations of internal integer variables produced by the SFTRAN3
preprocessor, xsf3(1L), as part of the translation of structured Fortran
statements to ordinary Fortran. These variables have six-character names of
the form NPRddd, NXdddd, N2dddd, and N3dddd, where d is a decimal digit.
Because they are invisible in the SFTRAN3 source code, and will change if the
SFTRAN3 code is modified, such variables should not be explicitly declared.
Instead, they should just assume the default Fortran INTEGER data type based
on their initial letter, N.

asterisk-comment (128):
Use an asterisk as the comment character; the default is otherwise 'C'.

comment-char-lowercase (256):
Use 'c' instead of 'C' or '*' as the comment character.

suppress-array-dimensions (512):
Suppress dimensioning of arrays in the generated declarations. This option
is for use with code lacking type declarations, to allow the declaration
files to be inserted without change into the code. Since the code will have
dimension statements already, dimensioning the array variables in the type
statements of the declaration file is redundant. This option should be used
only in conjunction with option 2 = undeclared-only because otherwise any
arrays that were dimensioned in a type statement will lose their
dimensioning.

free-form (1024):
Produce declarations in free source form. This mode is automatically used if
the input source is free form. Use this option to produce declarations in
free form even if the input is in fixed form. Free form declarations are
indented only 2 columns instead of 6, use the exclamation mark as the comment
character, and indicate continuation lines by an ampersand at the end of the
line to be continued.

The declaration files contain distinctive comments that mark the start and end of
declarations for each program unit, to facilitate using text editor macros for
merging the declarations back into the source code.

The ftnchek distribution includes a program, dcl2inc, which processes declaration
files to produce files containing declarations of all COMMON blocks, in a form
suitable for use as INCLUDE files. See the dcl2inc(1L) man page for the details of
its use.

See also: -mkhtml.

-mkhtml=list
Produce HTML documentation from source. Creates individual HTML files from ftnchek
analysis and code comments. All comments immediately preceding and following the
function or subroutine definition are captured to the HTML file. No reformatting of
source comments is performed other than stripping of FORTRAN comment characters.
In addition, the HTML file lists the local variables declared, common block
variables used, functions and subroutines called, I/O unit usage, and other
information about each subprogram. Usually you will also want to specify
-call=tree to create the root HTML file CallTree.html. (Perhaps this file should
be named index.html.)

Various options for the form of the HTML files are controlled by the list, which
consists of keywords separated by commas or colons. There are three special
keywords: all to turn on all the options, 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, -mkhtml is equivalent to -mkhtml=documents (i.e. produce the HTML document
files using the default options), and -nomkhtmls is equivalent to -mkhtml=none.

For the sake of simplicity, the options for -mkhtml are the same as those for
-makedcls except for those that are inapplicable. Likewise, a numeric form of
this setting can be used, formed as the sum of the numbers in parentheses in the
list below. The warning keywords with their meanings are as follows:

documents (1):
Create the HTML documents. (This is implied by any of the other options, and
can be omitted if any other options are given.)

compact (4):
The declarations are normally prettyprinted to line up neatly in common
columns. This option value selects instead compact output, without column
alignment.

use-continuation-lines (8):
Causes continuation lines to be used instead of beginning a new declaration
on each line. This option is appropriate to use together with compact.

keywords-lowercase (16):
Output Fortran keywords in lowercase, instead of the default uppercase.

vars-and-consts-lowercase (32):
Output variables and constants in lowercase, instead of the default
uppercase. Character string constants are not affected by this option.

exclude-sftran3 (64):
Omit declarations of internal integer variables produced by the SFTRAN3
preprocessor, xsf3(1L). (See -makedcls for discussion.)

suppress-array-dimensions (512):
Suppress dimensioning of arrays in the generated declarations. This is
normally undesirable, but is available if for some reason you do not want the
array dimensions to appear in the HTML.

free-form (1024):
Produce variable declarations in free source form. This mode is
automatically used if the input source is free form. This mainly affects the
form of continuation lines if they are used.

See also: -calltree, -makedcls.

-novice
This flag is intended to provide more helpful output for beginners. It has two
effects:

(a) provides an extra message to the effect that a function that is used but not
defined anywhere might be an array which the user forgot to declare in a
DIMENSION statement (since the syntax of an array reference is the same as that
of a function reference).

(b) modifies the form of the error messages and warnings. If the flag is turned
off by -nonovice, these messages are printed in a style more resembling UNIX
lint.

Default = yes.

-output=filename
This setting is provided for convenience on systems which do not allow easy
redirection of output from programs. When this setting is given, the output which
normally appears on the screen will be sent instead to the named file. Note,
however, that operational errors of ftnchek itself (e.g. out of space or cannot
open file) will still be sent to the screen. The extension for the filename is
optional, and if no extension is given, the extension .lis will be used.

-pointersize=num
Specifies the size of a ``Cray pointer'' variable to be num bytes. Default = turn-
on = 4 bytes.

The pointer size is used to inform precision mismatch warnings involving pointer
variables, for example when a pointer is assigned a value from an allocation
routine, or passed as a subprogram parameter.

See also: -f77, -portability, -truncation, -wordsize.

-portability=list
ftnchek will give warnings for a variety of non-portable usages. Examples include
the use of tabs except in comments or inside strings, the use of Hollerith
constants, and the equivalencing of variables of different data types. This option
does not produce warnings for supported extensions to the Fortran 77 Standard,
which may also cause portability problems. To catch those, use the -f77 setting.
By default, all warnings are turned off.

This setting provides detailed control over the warnings about possible portability
problems. The list consists of keywords separated by commas or colons. There are
three special keywords: all to turn on all the warnings about nonportable usages,
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, -portability is equivalent to
-portability=all, and -noportability is equivalent to -portability=none. The
warning keywords with their meanings are as follows:

backslash:
Backslash character in strings. Since some compilers treat the backslash as
an escape character, its presence can cause problems even though it is used
in a standard-conforming way.

common-alignment:
COMMON block variables not in descending order of storage size. Some
compilers require this ordering because of storage alignment requirements.

hollerith:
Hollerith constants (other than within FORMAT specifications). The Hollerith
data type is a feature of Fortran IV that has been deleted in the Fortran 77
standard. It is superseded by the character data type. Storing Hollerith
data in variables of a numeric or logical data type is nonportable due to
differing word sizes.

long-string:
String constants, variables, or expressions over 255 chars long.

mixed-equivalence:
Variables of different data types equivalenced.

mixed-size:
Variables declared with default precision used with variables given explicit
precision, in expressions, assignments, or as arguments. For example, if a
variable declared as REAL*8 is treated as equivalent to DOUBLE PRECISION.

real-do:
Non-integer DO loop index and bounds. These can cause a program's results to
depend on the hardware characteristics of the particular computer used.

param-implicit-type:
Implicit typing of a parameter by the data type of the value assigned, if it
differs from the default type. This warning can only occur if implicit
parameter typing has been turned on by the -source=param-implicit-type
option, or if the PARAMETER statement is of the nonstandard form without
parentheses. If this option is turned on, then any instances where implicit
parameter typing occurs and where the implicit type is different from the
default type based on the first letter of the parameter name, will be warned
about. Implicit parameter typing can change the semantics of statements
where the parameter is used, causing portability problems.

tab: Tabs in source code. Tabs are interpreted differently by different
compilers. This warning will be given only once, at the end of the file.

See also: -f77, -f90, -f95, -pretty, -style, -wordsize.

-pretty=list
Controls certain messages related to the appearance of the source code. These warn
about things that might make a program less readable or be deceptive to the reader.
By default, all warnings are turned on.

This setting provides detailed control over the warnings about appearance. The
list consists of keywords separated by commas or colons. Since all warnings are on
by default, include a keyword prefixed by no- to turn off a particular warning.
There are three special keywords: all to turn on all the warnings about misleading
appearances, 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, -pretty is
equivalent to -pretty=all, and -nopretty is equivalent to -pretty=none. The
warning keywords with their meanings are as follows:

alternate-return:
A RETURN statement has a constant specifying an alternate return point that
is not between 0 and the number of dummy arguments that are labels. This is
legal, and has the same effect as a RETURN with no alternate return
expression, but suggests that the programmer intended to use an alternate
return label that is not provided.

embedded-space:
Space embedded in variable names or in multi-character operators such as **.

continuation:
Continuation mark following a comment line.

long-line:
Lines (except comments) over 72 columns in width (beyond 72 is normally
ignored by compiler).

missing-space:
Lack of space between variable and a preceding keyword.

multiple-common:
COMMON block declared in multiple statements. No warning is given if the
statements are consecutive except for comment lines.

multiple-namelist:
NAMELIST declared in multiple statements. No warning is given if the
statements are consecutive except for comment lines.

parentheses:
Parentheses around a variable by itself. As a subprogram argument, this
makes the argument an expression, not modifiable by the subprogram.

Note that in free source form, extra space and missing space are forbidden by the
Fortran 90 Standard, and are not mere style violations. In this case the warnings
are replaced by syntax error messages, and can be turned off only by using
-nocheck.

See also: -f77, -portability, -style.

-project=list
ftnchek will create a project file from each source file that is input while this
option is turned on. The project file will be given the same name as the input
file, but with the extension .f or .for replaced by .prj. (If input is from
standard input, the project file is named ftnchek.prj.) Default = none.

The list consists of keywords separated by commas or colons. There are three
special keywords: all to turn on all the options, 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, -project is equivalent to -project=all, and -noproject is
equivalent to -project=none. The keywords with their meanings are as follows:

create:
Produce a project file. The default is not to produce a project file. If
this option is not turned on, the other options have no effect.

trim-calls:
Trim the amount of information stored in the project file about subprogram
declarations and calls. This is the default. Turn this option off only in
rare situations. (See discussion below.) The amount of trimming varies
depending on the -library flag. More information is trimmed if that flag is
turned on.

trim-common:
Trim the number of common block declarations stored in the project file.
This is the default. Turn this option off only in rare situations. (See
discussion below.) This option has no effect if the -library flag is turned
off: when not in library mode, no trimming of common block declarations is
done regardless of this option.

A project file contains a summary of information from the source file, for use in
checking agreement among FUNCTION, SUBROUTINE, and COMMON usages in other files.
It allows incremental checking, which saves time whenever you have a large set of
files containing shared subroutines, most of which seldom change. You can run
ftnchek once on each file with the -project flag set, creating the project files.
Usually you would also set the -library and -noextern flags at this time, to
suppress messages relating to consistency with other files. Only error messages
pertaining to each file by itself will be printed at this time. Thereafter, run
ftnchek without these flags on all the project files together, to check consistency
among the different files. All messages internal to the individual files will now
be omitted. Only when a file is altered will a new project file need to be made
for it.

Naturally, when the -project option is turned on, ftnchek will not read project
files as input.

Ordinarily, the trim options should be left on when you intend to create project
files for future input to ftnchek. Since trimming is on by default, this means
that simply giving the command -project with no option list is the recommended
mode. The trim options are provided only as a convenience for those who want to
make use of project files for purposes other than checking the program with
ftnchek. To use project files for their intended purpose, the trim options should
not be turned off.

Project files contain only information needed for checking agreement between files.
This means that a project file is of no use if all modules of the complete program
are contained in a single file.

A more detailed discussion is given in the section on Using Project Files.

-pure
Assume functions are ``pure'', i.e., they will not have side effects by modifying
their arguments or variables in a COMMON block. When this flag is in effect,
ftnchek will base its determination of set and used status of the actual arguments
on the assumption that arguments passed to a function are not altered. It will
also issue a warning if a function is found to modify any of its arguments or any
COMMON variables. Default = yes.

When this flag is turned off, actual arguments passed to functions will be handled
the same way as actual arguments passed to subroutines. This means that ftnchek
will assume that arguments may be modified by the functions. No warnings will be
given if a function is found to have side effects. Because stricter checking is
possible if functions are assumed to be pure, you should turn this flag off only if
your program actually uses functions with side effects.

-quiet
This option reduces the amount of output relating to normal operation, so that
error messages are more apparent. This option is provided for the convenience of
users who are checking large suites of files. The eliminated output includes the
names of project files, and the message reporting that no syntax errors were found.
It also eliminates some blank lines that are ordinarily included for clarity. (Some
of this output is turned back on by the -list and -symtab options.) Default = no.

Note: the way to remember the difference between the -quiet and -brief is that
-quiet doesn't suppress any warning-related information, whereas -brief does.

See also: -brief.

-reference
Specifies that a who-calls-who table be printed. This table lists each subprogram
followed by a list of the routines it calls. This switch is equivalent to
-calltree=reference. Default = no.

The reference list omits routines called by unused library modules. Thus it
contains the same information as for the call-tree format, namely the hierarchy of
subprogram calls, but printed in a different way. This prints out a breadth-first
traversal of the call tree whereas -calltree=tree prints out a depth-first
traversal.

See also: -calltree, -crossref, -library, -sort, -symtab, -vcg.

-resources
Prints the amount of resources used by ftnchek in processing the program. This
listing may be useful in analyzing the size and complexity of a program. It can
also help in choosing larger sizes for ftnchek's internal tables if they are too
small to analyze a particular program. Default = no.

In this listing, the term ``chunk size'' is the size of the blocks of memory
allocated to store the item in question, in units of the size of one item, not
necessarily in bytes. When the initially allocated space is filled up, more memory
is allocated in chunks of this size. The following is an explanation of the items
printed:

Source lines processed:
Total number of lines of code, with separate totals for statement lines and
comment lines. Comment lines include lines with 'C' or '*' in column 1 as well
as blank lines and lines containing only an inline comment. Statement lines
are all other lines, including lines that have an inline comment following some
code. Continuation lines are counted as separate lines. Lines in include
files are counted each time the file is included.

Total executable statements:
Number of statements in the program, other than specification, data, statement-
function, FORMAT, ENTRY, and END statements.

Total number of modules:
A module is any external subprogram, including the main program, subroutines,
functions, and block data units. This count is of modules defined within the
source, not modules referenced. Statement functions are not included. A
subprogram with multiple entry points is only counted once.

Total statement labels defined
Number of labels attached to statements (often called statement numbers). The
total label count for the entire program is given, as well as the maximum
number in any single subprogram.

Max identifier name chars:
Number of characters used for storing identifier names. An identifier is a
variable, subprogram, or common block name. Local names are those of local
variables in a subprogram, whereas global names refer to subprogram and common
block names, as well as dummy argument names and common variable names. Actual
argument text (up to 15 characters for each argument) is also included here.
The space used for local names is not recovered at the end of each module, so
this number, like global space, grows until the whole program is analyzed.
Unfortunately, this figure may include some text stored more than once,
although a heuristic is used that will avoid duplicates in many cases.

Max token text chars:
A token is the smallest syntactic unit of the FORTRAN language above the level
of individual characters. For instance a token can be a variable name, a
numerical constant, a quoted text string, or a punctuation character. Token
text is stored while a module is being processed. For technical reasons,
single-character tokens are not included in this total. Items that are not
represented in the symbol table may be duplicated. The space for token text is
recovered at the end of each module, so this figure represents the maximum for
any one module.

Max local symbols:
This is the largest number of entries in the local symbol table for any module.
Local symbol table entries include all variables and parameters, common block
names, statement functions, external subprograms and intrinsic functions
referenced by the module. Literal constants are not stored in the local symbol
table.

Max global symbols:
This is the number of entries in the global symbol table at the end of
processing. Global symbol table entries include external subprogram and common
block names. Intrinsic functions and statement functions are not included.

Max number of tokenlists:
A token list is a sequence of tokens representing the actual or dummy argument
list of a subprogram, or the list of variables in a common block or namelist.
Therefore this number represents the largest sum of COMMON, CALL, NAMELIST and
ENTRY statements and function invocations for any one module. The space is
recovered at the end of each module.

Max token list/tree space:
This is the largest number of tokens in all the token lists and token trees of
any one module. A token tree is formed when analyzing an expression: each
operand is a leaf of the tree, and the operators are the nodes. Therefore this
number is a measure of the maximum complexity of an individual module. For
instance a module with many long arithmetic expressions will have a high
number. Note that unlike token text described above, the number of tokens is
independent of the length of the variable names or literal constants in the
expressions.

Number of subprogram invocations:
This is the sum over all modules of the number of CALL statements and function
invocations (except intrinsic functions and statement functions).

Number of common block decls:
This is the sum over all modules of the number of common block declarations.
That is, each declaration of a block in a different module is counted
separately. (The standard allows multiple declarations of a block within the
same module; these are counted as only one declaration since they are
equivalent to a single long declaration.)

Number of array dim & param ptrs:
This is the sum over all modules of the number of array dimension and parameter
definition text strings saved for use by the -makedcls option. The length of
the text strings is not counted. Each dimension of a multidimensional array is
counted separately.

These numbers are obviously not the same when project files are used in place of
the original source code. Even the numbers for global entities may be different,
since some redundant information is eliminated in project files.

-sixchar
One of the goals of the ftnchek program is to help users to write portable Fortran
programs. One potential source of nonportability is the use of variable names that
are longer than six characters. Some compilers just ignore the extra characters.
This behavior could potentially lead to two different variables being considered as
the same. For instance, variables named AVERAGECOST and AVERAGEPRICE are the same
in the first six characters. If you wish to catch such possible conflicts, use
this flag. Default = no.

Use the -f77=long-names if you want to list all variables longer than six
characters, not just those pairs that are the same in the first six.

See also: -f77, -portability.

-sort
Specifies that a sorted list of all modules used in the program be printed. This
list is in ``prerequisite'' order, i.e. each module is printed only after all the
modules from which it is called have been printed. This is also called a
``topological sort'' of the call tree. Each module is listed only once. Routines
that are not in the call tree of the main program are omitted. If there are any
cycles in the call graph (illegal in standard Fortran) they will be detected and
diagnosed. Default = no.

See also: -calltree, -crossref, -reference, -symtab, -vcg.

-source=list
This setting controls certain options about the form of the Fortran source code.
The list consists of keywords separated by commas or colons. There are three
special keywords: all to turn on all the options, 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, -source is equivalent to -source=all, and -nosource is equivalent
to -source=none.

For compatibility with previous versions of ftnchek, a numeric form of this setting
is also accepted: the list is replaced by a number which is the sum of the numbers
in parentheses beside the keywords in the following list. (The fixed and free
options do not have numeric values.) The warning keywords with their meanings are
as follows:

fixed:
Interpret the source as fixed form (with supported extensions such as
exclamation mark for comments). Statements must be in columns 7 to 72
(unless the -cols setting has been used to change this), and blanks are not
significant outside character context (but warned about under the -pretty
option). This is the default mode unless the source file extension is .f90
or .F90. this option cannot be given together with -source=free.

free: Interpret the source as free form. Statements may be anywhere in columns 1
to 132, comments can only begin with an exclamation mark, and blanks are
required in some places such as between identifiers and keywords. This is
the default mode if the source file extension is .f90 or .F90. This option
cannot be given together with -source=fixed or -source=dec-tab

dec-tab (1):
Accept DEC-style tab-formatted source. A line beginning with an initial tab
will be treated as a new statement line unless the character after the tab is
a nonzero digit, in which case it is treated as a continuation line. The
next column after the tab or continuation mark is taken as column 7. A
warning will be given in the case where the line is a continuation, if
-f77=dec-tab is in effect.

vms-include (2):
Accept VMS-style INCLUDE statements. These follow the normal syntax, but
with the following additional features: (1) the file extension, if not given,
defaults to the same as a normal source file extension; and (2) the option
/LIST or /NOLIST can be appended to the include-file name, to control listing
of its contents.

unix-backslash (4):
Handle UNIX-style backslash escapes in character strings. The escape
sequence following the backslash will be evaluated according to the ANSI
standard for strings in C: up to three digits signify an octal value, an x
signifies the start of a hexadecimal constant, any of the letters a b f n r t
signify special control codes, and any other character (including newline)
signifies the character itself. When this source code option is in effect, a
warning will be given if the -f77=backslash setting is specified.

The default behavior is to treat the backslash like any other normal
character, but a warning about portability will be generated if the
-portability flag is set. Because of the fact that some compilers treat the
backslash in a nonstandard way, it is possible for standard-conforming
programs to be non-portable if they use the backslash character in strings.

Since ftnchek does not do much with the interpreted string, it is seldom
necessary to use this option. It is needed in order to avoid spurious
warnings only if (a) the program being checked uses backslash to embed an
apostrophe or quote mark in a string instead of using the standard mechanism
of doubling the delimiter; (b) the backslash is used to escape the end-of-
line in order to continue a string across multiple source lines; or (c) a
PARAMETER definition uses an intrinsic string function such as LEN with such
a string as argument, and that value is later used to define array
dimensions, etc.

param-implicit-type (8):
Implicit typing of a parameter by the data type of the value assigned. Some
non-standard compilers may allow the data type of the value to override the
Fortran 77 default type of a parameter that is based on the first letter of
the parameter name. This option only applies to PARAMETER statements of the
standard form which has parentheses. A parameter that has been explicitly
declared in a type statement prior to the PARAMETER statement is not affected
by this option. A warning will be given under the -f77=param-implicit-type
or -portability=param-implicit-type option.

Note that this implicit typing is treated as equivalent to an explicit type
declaration for the parameter. Therefore, if you use
-makedcls=undeclared-only to generate declarations only of undeclared
variables, these parameters will not be included.

dec-param-standard-type (16):
Follow the Fortran 77 rule for data typing of DEC Fortran style parameters.
These are declared using a nonstandard form of the PARAMETER statement which
lacks parentheses. According to DEC Fortran, parameters defined by this form
of the statement have their data type given by the data type of the value
assigned. Use this option to tell ftnchek not to follow this rule but
instead to use the same rule as for standard PARAMETER statements. This
option does not apply to PARAMETER statements of the standard form.

By default, all these source code options are turned off, except for the
vms-include option, which is on by default in the VMS version..

See also: -f77, -include, -portability.

-style=list
Provides extra-picky warnings about obsolescent or old-fashioned programming
constructions. This option is helpful for efforts to follow a modern programming
style. (Most of the things complained about under this option are forbidden in the
F subset language.) By default, all warnings are turned off.

The list consists of keywords separated by commas or colons. There are three
special keywords: all to turn on all the options, 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, -style is equivalent to -style=all, and -nostyle is equivalent to
-style=none. The warning keywords with their meanings are as follows:

block-if:
Complain about arithmetic IF statement. Accept block IF or logical IF (which
controls a single statement).

construct-name:
Complain about unnamed block constructs: IF, DO, and SELECT CASE. Note that
if a construct name is present on the opening statement of a construct, then
it is required to be present on all other component statements (ELSE, END IF,
etc.) of the construct. In that case a missing construct name on those
statements generates a syntax error regardless of this option. The purpose
of this option is to warn if the construct completely lacks the optional
name.

distinct-do:
Complain if two DO loops share a common terminator statement.

do-construct:
Complain if terminator of a DO loop is anything other than an END DO or
CONTINUE statement. This is the requirement in order for the loop to meet
the Fortran 90 definition of a do-construct.

do-enddo:
Complain if terminator of a DO loop is anything other than an END DO
statement. (This option overrides the do-construct option, being even
stricter.)

end-name:
Complain about the absence of the subprogram name on structured END
statements.

format-stmt:
Complain about the presence of FORMAT statements. Only the FORMAT statements
themselves are flagged, not the references to them in I/O lists.

goto: Complain about the presence of unconditional, computed or assigned GOTO
statements. Also complain about alternate returns (but not about labels as
subprogram arguments).

labeled-stmt:
Complain about the presence of labels (numbers) on statements other than
FORMAT statements. (Since FORMAT statements are arguably convenient and not
readily abused, complaints about them are controlled by the separate
format-stmt keyword.)

program-stmt:
Complain about the absence of a PROGRAM statement at the head of the main
program.

structured-end:
Complain about the use of a plain END statement to end a subprogram, rather
than a structured END statement (END PROGRAM, END SUBROUTINE, END FUNCTION,
or END BLOCK DATA).

See also: -f77, -f90, -f95, -pretty, -portability.

-symtab
A symbol table will be printed out for each module, listing all identifiers
mentioned in the module. This table gives the name of each variable, its datatype,
and the number of dimensions for arrays. An asterisk (*) indicates that the
variable has been implicitly typed, rather than being named in an explicit type
declaration statement. The table also lists all subprograms invoked by the module,
all COMMON blocks declared, etc. Default = no.

Also, for each module, a label table will be printed. The table lists each label
defined in the module; the line on which said statement label is defined; and the
statement type (executable, format, or specification). The labels are listed in
sequential order.

Also printed is a table describing the I/O units used by the module, together with
information about how they are used: what operations are performed, whether the
access is sequential or direct, and whether the I/O is formatted or unformatted.

See also: -calltree, -crossref, -list, -reference, -sort, -vcg.

-truncation=list
Warn about possible truncation (or roundoff) errors. Most of these are related to
integer arithmetic. By default, all warnings are turned on.

This setting provides detailed control over the warnings about possible truncation
errors. The list consists of keywords separated by commas or colons. Since all
warnings are on by default, include a keyword prefixed by no- to turn off a
particular warning. There are three special keywords: all to turn on all the
warnings about truncation, 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, -truncation
is equivalent to -truncation=all, and -notruncation is equivalent to
-truncation=none. The warning keywords with their meanings are as follows:

int-div-exponent:
use of the result of integer division as an exponent. This suggests that a
real quotient is intended. An example would be writing X**(1/3) to evaluate
the cube root of X. The correct expression is X**(1./3.).

int-div-real:
Conversion of an expression involving an integer division to real. This
suggests that a real quotient is intended.

int-div-zero:
division in an integer constant expression that yields a result of zero.

int-neg-power:
exponentiation of an integer by a negative integer (which yields zero unless
the base integer is 1 in magnitude). This suggests that a real base is
intended.

promotion:
automatic conversion of a lower precision quantity to one of higher
precision. The loss of accuracy for real variables in this process is
comparable to the corresponding demotion. No warning is given for promotion
of integer quantities to real since this is ordinarily exact.

real-do-index:
use of a non-integer DO index in a loop with integer bounds. An integer DO
index with real bounds is always warned about regardless of this setting.

real-subscript:
use of a non-integer array subscript.

significant-figures:
overspecifying a single precision constant. This may indicate that a double
precision constant was intended.

size-demotion:
automatic conversion of a higher precision quantity to one of lower precision
of the same type. This warning only occurs when an explicit size is used in
declaring the type of one or both operands in an assignment. For example, a
warning wil be issued where a REAL*8 variable is assigned to a REAL variable,
if the default wordsize of 4 is in effect. A warning is also issued if a
long integer is assigned to a shorter one, for example, if an INTEGER
expression is assigned to an INTEGER*2 variable. There is one exception to
this last case, namely if the right hand side of the assignment is a small
literal constant (less than 128). type-demotion: automatic conversion of a
higher precision quantity to one of lower precision of different type. This
warning includes conversion of real quantities to integer, double precision
to single precision real, and assignment of a longer character string to a
shorter one.

The warnings about promotion and demotion also apply to complex constants,
considering the precision to be that of the real or imaginary part. Warnings about
promotions and demotions are given only when the conversion is done automatically,
e.g. in expressions of mixed precision or in an assignment statement. If intrinsic
functions such as INT are used to perform the conversion, no warning is given.

See also: -portability, -wordsize.

-usage=list
Warn about unused or possible uninitialized variables, unused common blocks,
undefined or unused statement labels, and unused or undefined subprograms. By
default, all warnings are turned on.

This setting provides detailed control over the warnings about possible usage
errors. The list consists of keywords separated by commas or colons. Since all
warnings are on by default, include a keyword prefixed by no- to turn off a
particular warning. There are three special keywords: all to turn on all the
warnings about usage, 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, -usage is
equivalent to -usage=all, and -nousage is equivalent to -usage=none. These
warnings cover four main categories of objects: subprogram dummy arguments, common
blocks and variables, subprograms and functions, and local variables. Warnings
include undefined items, multiply defined items, unused items, etc. The warning
keywords with their meanings are as follows:

arg-alias:
a scalar dummy argument is actually the same as another and is (or may be)
modified. The Fortran 77 standard (section 15.9.3.6) prohibits modifying an
argument that is aliased to another.

arg-array-alias:
a dummy argument which is an array or array element is in the same array as
another and is modified. This flag is similar to arg-alias but provides
separate control over array arguments. It is harder to tell if aliasing is
occurring in the case of arrays, so if ftnchek gives too many false warnings,
this flag allows the array-related ones to be turned off without suppressing
the warnings for scalars.

arg-common-alias:
a scalar dummy argument is the same as a common variable in the subprogram,
and either is modified. This is also prohibited by the Fortran 77 standard.
If common checking is not exact (see the -common setting), it is harder to
tell if aliasing is occurring, so the warning is given if the variable is
anywhere in a common block that is declared by the subprogram.

arg-common-array-alias:
a dummy argument which is an array or array element is in the same array as a
common variable, and either is modified. If common checking is not exact,
the variable can be anywhere in a common block that is declared by the
subprogram.

arg-const-modified:
a subprogram modifies an argument which is a constant or an expression. Such
an action could cause anomalous behavior of the program.

arg-unused:
a dummy argument is declared but never used. This is similar to the
var-unused keyword described below, but applies only to arguments.

com-block-unused:
a common block is declared but none of the variables in it are used by any
subprogram. This warning is suppressed if the common strictness setting is
0.

com-block-volatile:
a common block may lose the definition of its contents if common blocks are
volatile. This option only has an effect if the -common=volatile flag is in
effect. See the discussion of the -common setting above.

com-var-set-unused:
a common variable is assigned a value, but its value is not used by any
subprogram. This warning is suppressed if the common strictness setting is
0.

com-var-uninitialized:
a common variable's value is used in some subprogram, but is not set
anywhere. Unfortunately, ftnchek does not do a thorough enough analysis of
the calling sequence to know which routines are called before others. So
warnings about this type of error will only be given for cases in which a
variable is used in some routine but not set in any other routine. Checking
of individual COMMON variables is done only if the -common setting is 3
(variable by variable agreement). This warning is suppressed if the common
strictness setting is 0.

com-var-unused:
a common variable is declared but not used by any subprogram. This warning
is suppressed if the common strictness setting is 0.

do-index-modified:
a variable that is the index of a DO loop is modified by some statement
within the range of the loop. The Standard permits an active DO variable to
be modified only by the incrementation mechanism of the DO statement.

ext-multiply-defined:
an external (a subroutine or function) is defined more than once. Definition
of an external means providing the body of its source code.

ext-declared-only:
a name is declared in an EXTERNAL statement in some module, but is not
defined or used anywhere.

ext-undefined:
an external is used (invoked) but not defined anywhere. This option is
equivalent to the -external flag. If the subprogram is invoked more than
once, those invocations will still be checked for consistency.

ext-unused:
an external is defined (its subprogram body is present) but it is not used.
A subprogram is considered unused even if it is invoked by some other
subprogram, if it cannot be called from any thread of execution starting with
the main program. The agreement of the subprogram's arguments with its
invocations is still checked even if this warning is turned off. If there is
no main program, then this warning is issued only if the subprogram is not
invoked anywhere. This warning is suppressed in library mode, but library
mode has the additional effect of suppressing argument checking for unused
routines.

label-undefined:
a statement refers to a label that has not been defined.

label-unused:
a statement label is defined, but never referred to.

var-set-unused:
a local variable is assigned a value, but that value is not used.

var-uninitialized:
a local variable's value may be used before it is assigned. Sometimes
ftnchek makes a mistake in the warnings about local variable usage. Usually
it errs on the side of giving a warning where no problem exists, but in rare
cases it may fail to warn where the problem does exist. See the section on
Bugs for examples. If variables are equivalenced, the rule used by ftnchek
is that a reference to any variable implies the same reference to all
variables it is equivalenced to. For arrays, the rule is that a reference to
any array element is treated as a reference to all elements of the array.

var-unused:
a local variable is declared (for instance, in a type declaration) but is not
used in the module. Does not apply to dummy arguments: warnings about them
are controlled by the keyword arg-unused described above.

Note: In versions of ftnchek prior to 2.10, the -usage flag took a numeric argument
instead of a list of options. For the sake of users who may have written scripts
invoking ftnchek in this way, the numeric form is still accepted. The numeric
setting is composed of three digits. The first digit (hundreds place) controls
warnings about subprograms (functions and subroutines), the second digit (tens
place) warnings about common blocks and common variables,, and the third digit
(ones place) warnings about local variables. Each digit controls warnings
according to the convention that a 1 means warn about undefined items and variables
that are used before set, a 2 means warn about items that are unused, and a 3 means
warn about both types. These numbers are now converted to the appropriate values
for the above-listed keywords, except for com-block-volatile, which is not affected
by the numeric argument.

See also: -common, -declare, -extern, -library.

-vcg
Produce the call graph in the form of a VCG graph description. This description is
written to a separate file, with the same stem as the file containing the main
program, and suffix .vcg. This file is able to be given directly to xvcg(1L) to
visualize the call graph. (If input is from the standard input, then the graph
description is sent to standard output.) This switch is equivalent to
-calltree=vcg. Default = no.

The VCG description as created is more complex than it need be. VCG allows graphs
and nested subgraphs: each subroutine is created as a subgraph nested inside its
calling routines. This allows you to interactively display subgraphs or summarise
them.

The -vcg option for ftnchek was written by Dr. Philip Rubini of Cranfield
University, UK.

xvcg is a graph visualisation tool which runs under the X windows system. It is
freely available from ftp.cs.uni-sb.de. It was written by G. Sander of the
University of Saarland, Germany.

See also: -calltree, -crossref, -reference, -sort.

-version
This option causes ftnchek to print a line giving the version number, release date,
and patch level of the program. If no files are given, it then exits. If files
are given, the effect of this option is to include the patch level (normally
omitted) in the version information printed at the start of processing. Default =
no.

See also: -help.

-volatile
Assume that COMMON blocks are volatile. Default = no.

This flag is superseded by -common=volatile, and should no longer be used. It may
be eliminated in a future release of ftnchek.

See also: -common, -usage.

-wordsize=num
Specifies the default word size to be num bytes. This is the size of logical and
single-precision numeric variables that are not given explicit precisions.
(Explicit precisions for non-character variables are an extension to the Fortran 77
Standard, and are given by type declarations such as REAL*8 X.) Double-precision
and complex variables will be twice this value, and double complex variables four
times. Quad-precision constants and intrinsic function results will be four times
this value. Note that variables declared as REAL*16 will be regarded as quad
precision only if the word size is 4 bytes. Default = turn-on = 4 bytes.

The word size value does not matter for checking standard-conforming programs that
do not declare explicit precisions for non-character variables or store Hollerith
data in variables. This setting also does not affect the default size of character
variables, which is always 1 byte. Hollerith constants also are assumed to occupy
1 byte per character.

The word size is used to determine whether truncation occurs in assignment
statements, and to catch precision mismatches in subprogram argument lists and
common block lists. The exact warnings that are issued will depend on the status
of other flags. Under both the -portability=mixed-size and the -nowordsize flag,
any mixing of explicit with default precision objects (character expressions not
included) is warned about. This applies to arithmetic expressions containing both
types of objects, and to subprogram arguments and COMMON variables. Under control
of the -truncation=demotion and promotion options, a warning is given for
assignment of an expression to a shorter variable of the same type, or for
promotion of a lower precision value to higher precision in an arithmetic
expression or an assignment statement.

Giving a word size of 0, or equivalently, using -nowordsize means that no default
value will be assumed. This is equivalent to specifying -portability=mixed-size.
Use it to find cases of mixing default and explicit precision, for example to flag
places where REAL*8 is treated as equivalent to DOUBLE PRECISION.

See also: -pointersize, -portability, -truncation.

-wrap=col
Controls the wrapping of error messages. Long error messages that would run past
the specified column will be broken up into separate lines between the words of the
message for better readability. If turned off with -nowrap, each separate error
message will be printed on one line, leaving it up to the display to wrap the
message or truncate it. Default = turn-on = 79.

CHANGING THE DEFAULTS

ftnchek includes two mechanisms for changing the default values of all options: by
defining environment variables or by creating a preferences file. When ftnchek starts up,
it looks in its environment for any variables whose names are composed by prefixing the
string FTNCHEK_ onto the uppercased version of the option name. If such a variable is
found, its value is used to specify the default for the corresponding switch or setting.
In the case of settings (for example, the -common strictness setting) the value of the
environment variable is read as the default setting value. In the case of switches, the
default switch will be taken as true or yes unless the environment variable has the value
0 or NO.

Note that the environment variable name must be constructed with the full-length option
name, which must be in uppercase. For example, to make ftnchek print a source listing by
default, set the environment variable FTNCHEK_LIST to 1 or YES or anything other than 0 or
NO. The names FTNCHEK_LIS (not the full option name) or ftnchek_list (lower case) would
not be recognized.

Here are some examples of how to set environment variables on various systems. For
simplicity, all the examples set the default -list switch to YES.

1. UNIX, Bourne shell: $ FTNCHEK_LIST=YES
$ export FTNCHEK_LIST

2. UNIX, C shell: % setenv FTNCHEK_LIST YES

3. VAX/VMS: $ DEFINE FTNCHEK_LIST YES

4. MSDOS: $ SET FTNCHEK_LIST=YES

After processing any environment variables, ftnchek looks for a preferences file
containing options and settings. It will search in the following order, using only the
first file found: (1) .ftnchekrc in the current directory, (2) ftnchek.ini in the current
directory, (3) .ftnchekrc in the user's home directory, (4) ftnchek.ini in the home
directory. If such a file is found, the options defined in it are used as defaults in
place of the built-in defaults and overriding any defaults set in the environment..

Each option or setting in the preferences file must be on a separate line. They are given
in the same form as on the command line, except without the initial dash. The preferences
file can contain blank lines and comments. Comments are introduced at any point in a line
by a space character (blank or tab) or the '#' character, and are terminated by the end of
the line.

Command-line options override the defaults set in the environment or in the preferences
file, in the same way as they override the built-in defaults.

USING PROJECT FILES

This section contains detailed information on how to use project files most effectively,
and how to avoid some pitfalls.

One can divide the checks ftnchek does into two categories, local and global. Local
checking is restricted to within a single routine, and catches things like uninitialized
variables, unintended loss of precision in arithmetic expressions, etc. This sort of
checking can be done on each subprogram independently. Furthermore, local checking of a
subprogram does not need to be repeated when some other subprogram is changed. Global
checking catches things like calling a subroutine with the wrong argument types, or
disagreeing in common block declarations. It requires looking at the whole set of
subprograms interacting with each other.

The purpose of project files is to allow the local checking and global checking steps to
be separated. Assuming that each subprogram is in its own source file, you can run
ftnchek once on each one to do local checking while suppressing global checking. Then
ftnchek can be run once on all the project files together to do the global checking. The
sample makefile below shows how to automate this task. The ``.f.prj'' target updates a
project file for a particular file any time the source file changes. The information
needed for global checking is saved in the project file. The ``check'' target does the
combined global checking. Typically ``make check'' would repeat the ``ftnchek -project''
step only on changed source files, then do the global check. This is obviously a big
advantage for large programs, when many subprograms seldom if ever change.

It is best when using project files to place each subprogram in a separate source file.
If each source file may contain more than one subprogram, it complicates the definition
of ``local'' and ``global'' checking because there is some inter-module checking that is
contained within a file. ftnchek tries to do the right thing in this case, but there are
some complications (described below) due to the trade-off between avoiding re-doing cross-
checks and preserving information about the program's structure.

Ordinarily, to do the least amount of re-checking, project files should be created with
the -library flag in effect and trimming turned on. In this mode, the information saved
in the project file consists of all subprogram declarations, all subprogram invocations
not resolved by declarations in the same file, and one instance of each COMMON block
declaration. This is the minimum amount of information needed to check agreement between
files.

If the source file contains more than one routine, there are some possible problems that
can arise from creating the project file in library mode, because the calling hierarchy
among routines defined within the file is lost. Also, if the routines in the file make
use of COMMON blocks that are shared with routines in other files, there will not be
enough information saved for the correct checking of set and used status of COMMON blocks
and COMMON variables according to the -usage setting. Therefore if you plan to use
project files when -usage checking is turned on (which is the default situation), and if
multiple routines in one project file share COMMON blocks with routines in other files,
the project files should be created with the -library flag turned off. In this mode,
ftnchek saves, besides the information listed above, one invocation of each subprogram by
any other subprogram in the same file, and all COMMON block declarations. This means that
the project file will be larger than necessary, and that when it is read in, ftnchek may
repeat some inter-module checks that it already did when the project file was created. If
each project file contains only one module, there is no loss of information in creating
the project files in library mode.

Because of the possible loss of information entailed by creating a project file with the
-library flag in effect, whenever that project file is read in later, it will be treated
as a library file regardless of the current setting of the -library flag. On the other
hand, a project file created with library mode turned off can be read in later in either
mode.

The foregoing discussion assumes that the trimming options of the -project setting are
turned on when the project file is created. This is the normal situation. The no-trim
options of the -project setting are provided in case one wants to use the project files
for purposes other than checking the program with ftnchek. For instance, one could write
a Perl script to analyze the project files for information about how the different
subprograms are called. You should not use the no-trim options to deal with the issues of
information loss discussed above, since they cause more information than necessary to be
stored. This makes the project files bigger and causes ftnchek to do more work later when
it reads them to check your complete program. Ordinarily, you should use the -library
option to control how much information to store for later use by ftnchek in checking your
program.

Here is an example of how to use the UNIX make utility to automatically create a new
project file each time the corresponding source file is altered, and to check the set of
files for consistency. Add these lines to your makefile. The example assumes that a
macro OBJS has been defined which lists all the names of object files to be linked
together to form the complete executable program. (In this makefile, the indented lines
should each begin with a tab, not blanks.) If any source file contains multiple routines
that share common blocks among themselves, then the no-com-\* option should be removed
from NOGLOBAL, and/or drop the -library flag.
# tell make what a project file suffix is
.SUFFIXES: .prj

# these options suppress global checks.
NOGLOBAL=-usage=no-ext-undefined,no-com-\*

# tell make how to create a .prj file from a .f file
.f.prj:
ftnchek -project $(NOGLOBAL) -library $<

# set up macro PRJS containing project filenames
PRJS= $(OBJS:.o=.prj)

# "make check" will check everything that has been changed.
check: $(PRJS)
ftnchek $(PRJS)

When a program uses many routines defined in a large number of different source files in
different directories, it can be cumbersome to specify all the different project files
needed to check the program properly. To deal with such cases, ftnchek allows project
files to be concatenated into a single large file. This single file can then be given to
ftnchek to provide the information for checking the use of any or all of the routines
defined in the combined project files. When using such a ``library'' project file, you
may want ftnchek's error reports to document precisely the name of the file where the
specific function is defined. If the various source files are in several directories, an
error report that gives only the file name may be ambiguous, and rather should include the
path to the file. The solution is to create each of the individual project files by
giving the complete path to the source file. Then this complete path will appear in the
error reports. For example, suppose that all of the library subprogram source files are
in subdirectories of a directory named /util/lib. Then the individual project files could
first be created by a command such as
find /util/lib -name '*.f' -exec ftnchek -project '{}' ';'
(Possibly other options would be provided to ftnchek as discussed above. Also, this step
could be handled instead by a revised makefile rule that would provide the complete source
file path instead of just the local name when invoking ftnchek.) Next, concatenate all of
these project files manually.
find /util/lib -name '*.prj' -exec cat '{}' ';' > ourlib.prj
Then a program source file can be checked by using the command
ftnchek prog.f ... -lib ourlib.prj
and an error message related to any library routine will include the full path to the
routine's source file.

At present, there is no archive utility like ar to manage the contents of a concatenated
project file like the one in the illustration above. If changes are made to one of the
library routines, the only way to update the combined project file is to concatenate all
the individual project files once again. Such a utility would be quite easy to write.
Someone should do so and contribute it to the ftnchek effort.

AN EXAMPLE

The following simple Fortran program illustrates the messages given by ftnchek. The
program is intended to accept an array of test scores and then compute the average for the
series.

C AUTHORS: MIKE MYERS AND LUCIA SPAGNUOLO
C DATE: MAY 8, 1989

C Variables:
C SCORE -> an array of test scores
C SUM -> sum of the test scores
C COUNT -> counter of scores read in
C I -> loop counter

REAL FUNCTION COMPAV(SCORE,COUNT)
INTEGER SUM,COUNT,J,SCORE(5)

DO 30 I = 1,COUNT
SUM = SUM + SCORE(I)
30 CONTINUE
COMPAV = SUM/COUNT
END

PROGRAM AVENUM
C
C MAIN PROGRAM
C
C AUTHOR: LOIS BIGBIE
C DATE: MAY 15, 1990
C
C Variables:
C MAXNOS -> maximum number of input values
C NUMS -> an array of numbers
C COUNT -> exact number of input values
C AVG -> average returned by COMPAV
C I -> loop counter
C

PARAMETER(MAXNOS=5)
INTEGER I, COUNT
REAL NUMS(MAXNOS), AVG
COUNT = 0
DO 80 I = 1,MAXNOS
READ (5,*,END=100) NUMS(I)
COUNT = COUNT + 1
80 CONTINUE
100 AVG = COMPAV(NUMS, COUNT)
END

The compiler gives no error messages when this program is compiled. Yet here is what
happens when it is run:

$ run average
70
90
85
<EOF>
$

What happened? Why didn't the program do anything? The following is the output from
ftnchek when it is used to debug the above program:

$ ftnchek -list -symtab average

FTNCHEK Version 3.3 November 2004

File average.f:

1 C AUTHORS: MIKE MYERS AND LUCIA SPAGNUOLO
2 C DATE: MAY 8, 1989
3
4 C Variables:
5 C SCORE -> an array of test scores
6 C SUM -> sum of the test scores
7 C COUNT -> counter of scores read in
8 C I -> loop counter
9
10 REAL FUNCTION COMPAV(SCORE,COUNT)
11 INTEGER SUM,COUNT,J,SCORE(5)
12
13 DO 30 I = 1,COUNT
14 SUM = SUM + SCORE(I)
15 30 CONTINUE
16 COMPAV = SUM/COUNT
^
Warning near line 16 col 20: integer quotient expr SUM/COUNT converted to
real
17 END

Module COMPAV: func: real

Variables:

Name Type Dims Name Type Dims Name Type Dims Name Type Dims
COMPAV real COUNT intg I intg* J intg
SCORE intg 1 SUM intg

* Variable not declared. Type has been implicitly defined.

Warning in module COMPAV: Variables declared but never referenced:
J declared at line 11

Warning in module COMPAV: Variables may be used before set:
SUM used at line 14
SUM set at line 14

Statement labels defined:

Label Line StmtType
<30> 15 exec

18
19
20 PROGRAM AVENUM
21 C
22 C MAIN PROGRAM
23 C
24 C AUTHOR: LOIS BIGBIE
25 C DATE: MAY 15, 1990
26 C
27 C Variables:
28 C MAXNOS -> maximum number of input values
29 C NUMS -> an array of numbers
30 C COUNT -> exact number of input values
31 C AVG -> average returned by COMPAV
32 C I -> loop counter
33 C
34
35 PARAMETER(MAXNOS=5)
36 INTEGER I, COUNT
37 REAL NUMS(MAXNOS), AVG
38 COUNT = 0
39 DO 80 I = 1,MAXNOS
40 READ (5,*,END=100) NUMS(I)
41 COUNT = COUNT + 1
42 80 CONTINUE
43 100 AVG = COMPAV(NUMS, COUNT)
44 END

Module AVENUM: prog

External subprograms referenced:

COMPAV: real*

Variables:

Name Type Dims Name Type Dims Name Type Dims Name Type Dims
AVG real COUNT intg I intg MAXNOS intg*
NUMS real 1

* Variable not declared. Type has been implicitly defined.

Warning in module AVENUM: Variables set but never used:
AVG set at line 43

I/O Operations:

Unit ID Unit No. Access Form Operation Line
5 SEQ FMTD READ 40

Statement labels defined:

Label Line StmtType Label Line StmtType
<80> 42 exec <100> 43 exec

0 syntax errors detected in file average.f
6 warnings issued in file average.f

Warning: Subprogram COMPAV argument data type mismatch at position 1:
Dummy arg SCORE in module COMPAV line 10 file average.f is type intg
Actual arg NUMS in module AVENUM line 43 file average.f is type real

According to ftnchek, the program contains variables which may be used before they are
assigned an initial value, and variables which are not needed. ftnchek also warns the
user that an integer quotient has been converted to a real. This may assist the user in
catching an unintended roundoff error. Since the -symtab flag was given, ftnchek prints
out a table containing identifiers from the local module and their corresponding datatype
and number of dimensions. Finally, ftnchek warns that the function COMPAV is not used
with the proper type of arguments.

With ftnchek's help, we can debug the program. We can see that there were the following
errors:

1. SUM and COUNT should have been converted to real before doing the division.

2. SUM should have been initialized to 0 before entering the loop.

3. AVG was never printed out after being calculated.

4. NUMS should have been declared INTEGER instead of REAL.

We also see that I, not J, should have been declared INTEGER in function COMPAV. Also,
MAXNOS was not declared as INTEGER, nor COMPAV as REAL, in program AVENUM. These are not
errors, but they may indicate carelessness. As it happened, the default type of these
variables coincided with the intended type.

Here is the corrected program, and its output when run:

C AUTHORS: MIKE MYERS AND LUCIA SPAGNUOLO
C DATE: MAY 8, 1989
C
C Variables:
C SCORE -> an array of test scores
C SUM -> sum of the test scores
C COUNT -> counter of scores read in
C I -> loop counter
C
REAL FUNCTION COMPAV(SCORE,COUNT)
INTEGER SUM,COUNT,I,SCORE(5)
C
SUM = 0
DO 30 I = 1,COUNT
SUM = SUM + SCORE(I)
30 CONTINUE
COMPAV = FLOAT(SUM)/FLOAT(COUNT)
END
C
C
PROGRAM AVENUM
C
C MAIN PROGRAM
C
C AUTHOR: LOIS BIGBIE
C DATE: MAY 15, 1990
C
C Variables:
C MAXNOS -> maximum number of input values
C NUMS -> an array of numbers
C COUNT -> exact number of input values
C AVG -> average returned by COMPAV
C I -> loop counter
C
C
INTEGER MAXNOS
PARAMETER(MAXNOS=5)
INTEGER I, NUMS(MAXNOS), COUNT
REAL AVG,COMPAV
COUNT = 0
DO 80 I = 1,MAXNOS
READ (5,*,END=100) NUMS(I)
COUNT = COUNT + 1
80 CONTINUE
100 AVG = COMPAV(NUMS, COUNT)
WRITE(6,*) 'AVERAGE =',AVG
END
$ run average
70
90
85
<EOF>
AVERAGE = 81.66666
$

With ftnchek's help, our program is a success!

INTERPRETING THE OUTPUT

The messages given by ftnchek include not only syntax errors but also warnings and
informational messages about things that are legal Fortran but that may indicate errors or
carelessness. Most of these messages can be turned off by command-line options. Which
option controls each message depends on the nature of the condition being warned about.
See the descriptions of the command-line flags in the previous sections, and of individual
messages below. Each message is prefixed with a word or phrase indicating the nature of
the condition and its severity.

``Error'' means a syntax error. The simplest kind of syntax errors are typographical
errors, for example unbalanced parentheses or misspelling of a keyword. This type of
error is caught by the parser and appears with the description ``parse error'' or ``syntax
error'' (depending on the version of the parser generator and whether it is GNU bison or
UNIX yacc). This type of error message cannot be suppressed. Be aware that this type of
error often means that ftnchek has not properly interpreted the statement where the error
occurs, so that its subsequent checking operations will be compromised. You should
eliminate all syntax errors before proceeding to interpret the other messages ftnchek
gives.

``Warning: Nonstandard syntax'' indicates an extension to Fortran that ftnchek supports
but that is not according to the Fortran 77 Standard. The extensions that ftnchek accepts
are described in the section on Extensions below. One example is the DO ... ENDDO
construction. If a program uses these extensions, warnings will be given according to
specifications under the -f77 setting. The default behavior is to give no warnings.

``Warning'' in other cases means a condition that is suspicious but that may or may not be
a programming error. Frequently these conditions are legal under the standard. Some are
illegal but do not fall under the heading of syntax errors. Usage errors are one example.
These refer to the possibility that a variable may be used before it has been assigned a
value (generally an error), or that a variable is declared but never used (harmless but
may indicate carelessness). The amount of checking for usage errors is controlled by the
-usage flag, which specifies the maximum amount of checking by default.

Truncation warnings cover situations in which accuracy may be lost unintentionally, for
example when a double precision value is assigned to a real variable. These warnings are
controlled by the -truncation setting, which is on by default.

``Nonportable usage'' warns about some feature that may not be accepted by some compilers
even though it is not contrary to the Fortran 77 Standard, or that may cause the program
to perform differently on different platforms. For example, equivalencing real and
integer variables is usually a non-portable practice. The use of extensions to the
standard language is, of course, another source of non-portability, but this is handled as
a separate case. To check a program for true portability, both the -portability and the
-f77 flags should be used. They are both turned off by default. The -wordsize setting is
provided to check only those nonportable usages that depend on a particular machine
wordsize.

``Possibly misleading appearance'' is used for legal constructions that may not mean what
they appear to mean at first glance. For example, Fortran is insensitive to blank space,
so extraneous space within variable names or the lack of space between a keyword and a
variable can convey the wrong impression to the reader. These messages can be suppressed
by turning off the -pretty flag, which is on by default.

Other messages that are given after all the files are processed, and having to do with
agreement between modules, do not use the word ``warning'' but generally fall into that
category. Examples include type mismatches between corresponding variables in different
COMMON block declarations, or between dummy and actual arguments of a subprogram. These
warnings are controlled by the -common and -arguments settings respectively. By default
both are set for maximum strictness of checking.

Another group of warnings about conditions that are often harmless refer to cases where
the array properties of a variable passed as a subprogram argument differ between the two
routines. For instance, an array element might be passed to a subroutine that expects a
whole array. This is a commonly-used technique for processing single rows or columns of
two-dimensional arrays. However, it could also indicate a programming error. The -array
setting allows the user to adjust the degree of strictness to be used in checking this
kind of agreement between actual and dummy array arguments. By default the strictness is
maximum.

``Oops'' indicates a technical problem, meaning either a bug in ftnchek or that its
resources have been exceeded.

The syntax error messages and warnings include the filename along with the line number and
column number. ftnchek has two different options for the appearance of these error
messages. If -novice is in effect, which is the default, the messages are in a style
approximating normal English. (In default style, the filename is not printed in messages
within the body of the program if -list is in effect.) The other style of error messages
is selected by the -nonovice option. In this style, the appearance of the messages is
similar to that of the UNIX lint program.

ftnchek is still blind to some kinds of syntax errors. The two most important ones are
detailed checking of FORMAT statements, and almost anything to do with control of
execution flow by means of IF, DO, and GOTO statements: namely correct nesting of control
structures, matching of opening statements such as IF ... THEN with closing statements
such as ENDIF, and the proper use of statement labels (numbers). Most compilers will
catch these errors. See the section on Limitations for a more detailed discussion.

If ftnchek gives you a syntax error message when the compiler does not, it may be because
your program contains an extension to standard Fortran which is accepted by the compiler
but not by ftnchek. (See the section on Extensions.) On a VAX/VMS system, you can use
the compiler option /STANDARD to cause the compiler to accept only standard Fortran. On
most UNIX or UNIX-like systems, this can be accomplished by setting the flag -ansi.

Many of the messages given by ftnchek are self-explanatory. Those that need some
additional explanation are listed below in alphabetical order.

Common block NAME: data type mismatch at position n
The n-th variable in the COMMON block differs in data type in two different
declarations of the COMMON block. By default (-common strictness level 3), ftnchek
is very picky about COMMON blocks: the variables listed in them must match exactly
by data type and array dimensions. That is, the legal pair of declarations in
different modules:
COMMON /COM1/ A,B
and
COMMON /COM1/ A(2)
will cause ftnchek to give warnings at strictness level 3. These two declarations
are legal in Fortran since they both declare two real variables. At strictness
level 1 or 2, no warning would be given in this example, but the warning would be
given if there were a data type mismatch, for instance, if B were declared INTEGER.
Controlled by -common setting.

Common block NAME has long data type following short data type
Some compilers require alignment of multi-byte items so that each item begins at an
address that is a multiple of the item size. Thus if a short (e.g. single-
precision real) item is followed by a long (e.g. double precision real) item, the
latter may not be aligned correctly. Controlled by -portability=common-alignment
option.

Common block NAME has mixed character and non-character variables
The ANSI standard requires that if any variable in a COMMON block is of type
CHARACTER, then all other variables in the same COMMON block must also be of type
CHARACTER. Controlled by -f77=mixed-common option.

Common block NAME: varying length
For -common setting level 2, this message means that a COMMON block is declared to
have different numbers of words in two different subprograms. A word is the amount
of storage occupied by one integer or real variable. For -common setting level 3,
it means that the two declarations have different numbers of variables, where an
array of any size is considered one variable. This is not necessarily an error,
but it may indicate that a variable is missing from one of the lists. Note that
according to the Fortran 77 Standard, it is an error for named COMMON blocks (but
not blank COMMON) to differ in number of words in declarations in different
modules. Given for -common setting 2 or 3.

Error: Badly formed logical/relational operator or constant

Error: Badly formed real constant
The syntax analyzer has found the start of one of the special words that begin and
end with a period (e.g. .EQ.), or the start of a numeric constant, but did not
succeed in finding a complete item of that kind.

Error: cannot be adjustable size in module NAME
A character variable cannot be declared with a size that is an asterisk in
parentheses unless it is a dummy argument, a parameter, or the name of the function
defined in the module.

Error: cannot be declared in SAVE statement in module NAME
Only local variables and common blocks can be declared in a SAVE statement.

Error: No path to this statement
ftnchek will detect statements which are ignored or by-passed because there is no
foreseeable route to the statement. For example, an unnumbered statement (a
statement without a statement label), occurring immediately after a GOTO statement,
cannot possibly be executed.

Error: Parse error
This means that the parser, which analyzes the Fortran program into expressions,
statements, etc., has been unable to find a valid interpretation for some portion
of a statement in the program. If your compiler does not report a syntax error at
the same place, the most common explanations are: (1) use of an extension to ANSI
standard Fortran that is not recognized by ftnchek, or (2) the statement requires
more lookahead than ftnchek uses (see section on Bugs).

NOTE: This message means that the affected statement is not interpreted.
Therefore, it is possible that ftnchek's subsequent processing will be in error, if
it depends on any matters affected by this statement (type declarations, etc.).

Error: Syntax error
This is the same as ``Error: Parse error'' (see above). It is generated if your
version of ftnchek was built using the UNIX yacc parser generator rather than GNU
bison.

Identifiers which are not unique in first six chars
Warns that two identifiers which are longer than 6 characters do not differ in the
first 6 characters. This is for portability: they may not be considered distinct
by some compilers. Controlled by -sixchar option.

Nonportable usage: argument precision may not be correct for intrinsic function
The precision of an argument passed to an intrinsic function may be incorrect on
some computers. Issued when a numeric variable declared with explicit precision
(e.g. REAL*8 X) is passed to a specific intrinsic function (e.g. DSQRT(X)).
Controlled by -portability=mixed-size and -wordsize.

Nonportable usage: character constant/variable length exceeds 255
Some compilers do not support character strings more than 255 characters in length.
Controlled by -portability=long-string.

Nonportable usage: File contains tabs
ftnchek expands tabs to be equivalent to spaces up to the next column which is a
multiple of 8. Some compilers treat tabs differently, and also it is possible that
files sent by electronic mail will have the tabs converted to blanks in some way.
Therefore files containing tabs may not be compiled correctly after being
transferred. ftnchek does not give this message if tabs only occur within comments
or character constants. Controlled by -portability=tab.

Nonportable usage: non-integer DO loop bounds
This warning is only given when the DO index and bounds are non-integer. Use of
non-integer quantities in a DO statement may cause unexpected errors, or different
results on different machines, due to roundoff effects. Controlled by
-portability=real-do.

Possibly it is an array which was not declared
This message is appended to warnings related to a function invocation or to an
argument type mismatch, for which the possibility exists that what appears to be a
function is actually meant to be an array. If the programmer forgot to dimension
an array, references to the array will be interpreted as function invocations.
This message will be suppressed if the name in question appears in an EXTERNAL or
INTRINSIC statement. Controlled by the -novice option.

Possibly misleading appearance: characters past 72 columns
The program is being processed with the statement field width at its standard value
of 72, and some nonblank characters have been found past column 72. In this case,
ftnchek is not processing the characters past column 72, and is notifying the user
that the statement may not have the meaning that it appears to have. These
characters might be intended by the programmer to be significant, but they will be
ignored by the compiler. Controlled by -pretty=long-line.

Possibly misleading appearance: Common block declared in more than one statement
Such multiple declarations are legal and have the same effect as a continuation of
the original declaration of the block. This warning is only given if the two
declarations are separated by one or more intervening statements. Controlled by
-pretty=multiple-common.

Possibly misleading appearance: Continuation follows comment or blank line
ftnchek issues this warning message to alert the user that a continuation of a
statement is interspersed with comments, making it easy to overlook. Controlled by
-pretty=continuation.

Possibly misleading appearance: Extraneous parentheses
Warns about parentheses surrounding a variable by itself in an expression. When a
parenthesized variable is passed as an argument to a subprogram, it is treated as
an expression, not as a variable whose value can be modified by the called routine.
Controlled by -pretty=parentheses.

Subprogram NAME: argument data type mismatch at position n
The subprogram's n-th actual argument (in the CALL or the usage of a function)
differs in datatype or precision from the n-th dummy argument (in the SUBROUTINE or
FUNCTION declaration). For instance, if the user defines a subprogram by
SUBROUTINE SUBA(X)
REAL X
and elsewhere invokes SUBA by
CALL SUBA(2)
ftnchek will detect the error. The reason here is that the number 2 is integer,
not real. The user should have written
CALL SUBA(2.0)

When checking an argument which is a subprogram, ftnchek must be able to determine
whether it is a function or a subroutine. The rules used by ftnchek to do this are
as follows: If the subprogram, besides being passed as an actual argument, is also
invoked directly elsewhere in the same module, then its type is determined by that
usage. If not, then if the name of the subprogram does not appear in an explicit
type declaration, it is assumed to be a subroutine; if it is explicitly typed it is
taken as a function. Therefore, subroutines passed as actual arguments need only
be declared by an EXTERNAL statement in the calling module, whereas functions must
also be explicitly typed in order to avoid generating this error message.
Controlled by -arguments setting.

Subprogram NAME: argument arrayness mismatch at position n
Similar to the preceding situation, but the subprogram dummy argument differs from
the corresponding actual argument in its number of dimensions or number of
elements. Controlled by -array together with -arguments settings.

Subprogram NAME: argument mismatch at position n
A character dummy argument is larger than the corresponding actual argument, or a
Hollerith dummy argument is larger than the corresponding actual argument.
Controlled by -arguments setting.

Subprogram NAME: argument usage mismatch
ftnchek detects a possible conflict between the way a subprogram uses an argument
and the way in which the argument is supplied to the subprogram. The conflict can
be one of two types, as outlined below.

Dummy arg is modified, Actual arg is const or expr
A dummy argument is an argument as named in a SUBROUTINE or FUNCTION statement and
used within the subprogram. An actual argument is an argument as passed to a
subroutine or function by the caller. ftnchek is saying that a dummy argument is
modified by the subprogram, implying that its value is changed in the calling
module. The corresponding actual argument should not be a constant or expression,
but rather a variable or array element which can be legitimately assigned to.
Controlled by the -usage=arg-const-modified option.

Dummy arg used before set, Actual arg not set
Here a dummy argument may be used in the subprogram before having a value assigned
to it by the subprogram. The corresponding actual argument should have a value
assigned to it by the caller prior to invoking the subprogram. Controlled by the
-usage=var-uninitialized option.

This warning is not affected by the -arguments setting.

Subprogram NAME invoked inconsistently
Here the mismatch is between the datatype of the subprogram itself as used and as
defined. For instance, if the user declares
INTEGER FUNCTION COUNT(A)
and invokes COUNT in another module as
N = COUNT(A)
without declaring its datatype, it will default to real type, based on the first
letter of its name. The calling module should have included the declaration
INTEGER COUNT

Given for -arguments setting 2 or 3.

Subprogram NAME: varying length argument lists:
An inconsistency has been found between the number of dummy arguments (parameters)
a subprogram has and the number of actual arguments given it in an invocation.
ftnchek keeps track of all invocations of subprograms (CALL statements and
expressions using functions) and compares them with the definitions of the
subprograms elsewhere in the source code. The Fortran compiler normally does not
catch this type of error. Given for -arguments setting 1 or 3.

Variable not declared. Type has been implicitly defined
When printing the symbol table for a module, ftnchek will flag with an asterisk all
identifiers that are not explicitly typed and will show the datatype that was
assigned through implicit typing. This provides support for users who wish to
declare all variables as is required in Pascal or some other languages. This
message appears only when the -symtab option is in effect. Alternatively, use the
-declare flag if you want to get a list of all undeclared variables.

Variables declared but never referenced
Detects any identifiers that were declared in your program but were never used,
either to be assigned a value or to have their value accessed. Variables in COMMON
are excluded. Controlled by the -usage=var-unused option.

Variables set but never used
ftnchek will notify the user when a variable has been assigned a value, but the
variable is not otherwise used in the program. Usually this results from an
oversight. Controlled by the -usage=var-set-unused option.

Variables used before set
This message indicates that an identifier is used to compute a value prior to its
initialization. Such usage may lead to an incorrect value being computed, since
its initial value is not controlled. Controlled by the -usage=var-uninitialized
option.

Variables may be used before set
Similar to used before set except that ftnchek is not able to determine its status
with certainty. ftnchek assumes a variable may be used before set if the first
usage of the variable occurs prior in the program text to its assignment.
Controlled by the -usage=var-uninitialized option.

Warning: DO index is not integer
This warning is only given when the DO bounds are integer, but the DO index is not.
It may indicate a failure to declare the index to be an integer. Controlled by
-truncation=real-do option.

Warning: integer quotient expr ... converted to real
The quotient of two integers results in an integer type result, in which the
fractional part is dropped. If such an integer expression involving division is
later converted to a real datatype, it may be that a real type division had been
intended. Controlled by -truncation=int-div-real option.

Warning: Integer quotient expr ... used in exponent
The quotient of two integers results in an integer type result, in which the
fractional part is dropped. If such an integer expression is used as an exponent,
it is quite likely that a real type division was intended. Controlled by
-truncation=int-div-exponent option.

Warning: NAME not set when RETURN encountered
The way that functions in Fortran return a value is by assigning the value to the
name of the function. This message indicates that the function was not assigned a
value before the point where a RETURN statement was found. Therefore it is
possible that the function could return an undefined value.

Warning: Nonstandard syntax: adjustable size cannot be concatenated here
The Fortran 77 Standard (sec. 6.2.2) forbids concatenating character variables
whose size is an asterisk in parentheses, except in an assignment statement.
Controlled by -f77=mixed-expr.

Warning: Nonstandard syntax : significant characters past 72 columns
This warning is given under the -f77=long-line setting if the -columns setting has
been used to increase the statement field width, and a statement has meaningful
program text beyond column 72. Standard Fortran ignores all text in those columns,
but some compilers do not. Thus the program may be treated differently by
different compilers.

Warning: Nonstandard syntax : Statement out of order.
ftnchek will detect statements that are out of the sequence specified for ANSI
standard Fortran 77. Table 1 illustrates the allowed sequence of statements in the
Fortran language. Statements which are out of order are nonetheless interpreted by
ftnchek, to prevent ``cascades'' of error messages. The sequence counter is also
rolled back to prevent repetition of the error message for a block of similar
statements. Controlled by the -f77=statement-order option.

--------------------------------------------------------
| | implicit
| parameter |---------------------
| | other specification
format |---------------|---------------------
and | | statement-function
entry | data |---------------------
| | executable
--------------------------------------------------------

Table 1

Warning: Possible division by zero
This message is printed out wherever division is done (except division by a
constant). Use it to help locate a runtime division by zero problem. Controlled
by -division option.

Warning: real truncated to intg
ftnchek has detected an assignment statement which has a real expression on the
right, but an integer variable on the left. The fractional part of the real value
will be lost. If you explicitly convert the real expression to integer using the
INT or NINT intrinsic function, no warning will be printed. A similar message is
printed if a double precision expression is assigned to a single precision
variable, etc. Controlled by -truncation=demotion option.

Warning: subscript is not integer
Since array subscripts are normally integer quantities, the use of a non-integer
expression here may signal an error. Controlled by -truncation=real-subscript
option.

Warning: Unknown intrinsic function
This message warns the user that a name declared in an INTRINSIC statement is
unknown to ftnchek. Probably it is a nonstandard intrinsic function, and so the
program will not be portable. The function will be treated by ftnchek as a user-
defined function. This warning is not suppressed by any option, since it affects
ftnchek's analysis of the program. However, if the intrinsic function is in one of
the supported sets of nonstandard intrinsics, you can use the -intrinsic setting to
cause ftnchek to recognize it.

LIMITATIONS AND EXTENSIONS

ftnchek accepts ANSI standard Fortran-77 programs with some minor limitations and numerous
common extensions.

Limitations:
The dummy arguments in statement functions are treated like ordinary variables of
the program. That is, their scope is the entire subprogram, not just the statement
function definition.

The checking of FORMAT statements is lax, tolerating missing separators (comma,
etc.) between format descriptors in places where the Standard requires them, and
allowing .d fields on descriptors that should not have them. It does warn under
-f77=format-edit-descr about nonstandard descriptor types (like O), and supported
extensions.

There are some syntactic extensions and Fortran 90 elements that ftnchek accepts
but does very little checking. For instance, pointer usage (whether the
nonstandard Cray syntax or the Fortran 90 syntax) is not checked other than for set
and used status. It is hoped that some day more thorough checking will be
implemented, but for now the user should regard the acceptance of these syntactic
features simply as a convenience to enable checking of other aspects of code that
contains them. See the section Extensions for specifics about what features are
accepted but not fully checked.

If a user-supplied subprogram has the same name as one of the nonstandard intrinsic
functions recognized by ftnchek, it must be declared in an EXTERNAL statement in
any routine that invokes it. Otherwise it will be subject to the checking normally
given to the intrinsic function. Since the nonstandard intrinsics are not
standard, this EXTERNAL statement is not required by the Fortran 77 Standard.
Using the -intrinsic=none setting, recognition of most nonstandard intrinsics
(excepting only those needed to support the double complex data type) can be turned
off. See the lists of supported nonstandard intrinsic functions under the
discussion of the -intrinsic setting above.

Extensions:
All of these extensions (except lower-case characters) will generate warnings if
the relevant -f77 option is set. Some of the extensions listed below are part of
the Fortran-90 Standard. These are indicated by the notation (F90).

Tabs are permitted, and translated into equivalent blanks which correspond to tab
stops every 8 columns. The standard does not recognize tabs. Note that some
compilers allow tabs, but treat them differently. The treatment defined for DEC
FORTRAN can be achieved using the -source=dec-tab setting.

Strings may be delimited by either quote marks or apostrophes. A sequence of two
delimiter characters is interpreted as a single embedded delimiter character.
(F90)

Strings may contain UNIX-style backslash escape sequences. They will be
interpreted as such if the -source=unix-backslash setting is given. Otherwise the
backslash character will be treated as a normal printing character.

Source code can be in either Fortran 90 free format or traditional fixed format.
(F90)

A semicolon is allowed as a statement separator. (F90)

Lower case characters are permitted, and are converted internally to uppercase
except in character strings. The standard specifies upper case only, except in
comments and strings. (F90)

Hollerith constants are permitted, in accordance with the Fortran 77 Standard,
appendix C. They should not be used in expressions, or confused with datatype
CHARACTER.

The letter 'D' (upper or lower case) in column 1 is treated as the beginning of a
comment. There is no option to treat such lines as statements instead of comments.

Statements may be longer than 72 columns provided that the setting -columns was
used to increase the limit. According to the standard, all text from columns 73
through 80 is ignored, and no line may be longer than 80 columns.

Variable names may be longer than six characters. The standard specifies six as
the maximum. ftnchek permits names up to 31 characters long (F90).

Variable names may contain underscores and dollar signs (or other non-alphabetic
characters as specified by the -identifier-chars option). These characters are are
treated the same as alphabetic letters. The default type for variables beginning
with these characters is REAL. In IMPLICIT type statements specifying a range of
characters, the dollar sign follows Z and is followed by underscore. (Any other
user-defined characters are treated the same as the dollar sign.) Fortran 90
permits underscores in variable names.

The UNIX version tolerates the presence of preprocessor directives, namely lines
beginning with the pound sign (#). These are treated as comments, except for #line
directives, which are interpreted, and are used to set the line number and source
file name for warnings and error messages. Note that #include directives are not
processed by ftnchek. Programs that use them for including source files should be
passed through the preprocessor before being input to ftnchek. As noted below,
ftnchek does process INCLUDE statements, which have a different syntax. An
optional program, ftnpp(1L) (available separately) provides preprocessing that
properly handles INCLUDE files.

The Fortran 90 DO ... ENDDO control structure is permitted. The CYCLE and EXIT
statements are accepted. All of these may have an optional do-construct name, but
construct names are not checked for consistency. (F90)

The Fortran 90 SELECT CASE construct is accepted. (F90)

Construct names are also accepted on IF, THEN, ELSE, ENDIF and SELECT CASE
statements. (F90)

The ACCEPT and TYPE statements (for terminal I/O) are permitted, with the same
syntax as PRINT.

The so-called ``Cray pointer'' syntax is tolerated. It is not the same as the
Fortran 90 POINTER statement. There is no real checking of the statement other
than basic syntax. The form of this statement is
POINTER (pointer, pointee) [,(pointer, pointee)]
The pointer variables are assigned a data type of INTEGER *4. Usage checking of
the pointee variables is suppressed, since in practice they are accessed indirectly
via the pointers.

The following Fortran 90 pointer related syntaxes are accepted: ALLOCATABLE,
POINTER, and TARGET statements and the same attributes in type declarations;
ALLOCATE, DEALLOCATE, and NULLIFY executable statements; pointer assignment using
=> operator; and the intrinsic functions ALLOCATED and ASSOCIATED. Little semantic
checking of pointer variables and operations is done beyond basic set and used
status. For instance, there is no checking for such errors as dangling pointers,
or use of unallocated arrays.

Statements may have any number of continuation lines. The Fortran 77 and Fortran
90 standards allow a maximum of 19 in fixed source form. The Fortran 90 standard
allows a maximum of 39 in free source form.

Relational (comparison) operators composed of punctuation, namely: < <= == /= > >=
are allowed. (F90)

Inline comments, beginning with an exclamation mark, are permitted. (F90)

NAMELIST I/O is supported. The syntax is the same as in Fortran 90.

FORMAT statements can contain a dollar sign to indicate suppression of carriage-
return. An integer expression enclosed in angle brackets can be used anywhere in a
FORMAT statement where the Fortran 77 Standard allows an integer constant (except
for the length of a Hollerith constant), to provide a run-time value for a repeat
specification or field width.

Nonstandard keywords are allowed in I/O statements, corresponding to those in VMS
Fortran.

The IMPLICIT NONE statement is supported. The meaning of this statement is that
all variables must have their data types explicitly declared. Rather than flag the
occurrences of such variables with syntax error messages, ftnchek waits till the
end of the module, and then prints out a list of all undeclared variables, as it
does for the -declare option. (F90)

Data types INTEGER, REAL, COMPLEX, and LOGICAL are allowed to have an optional
precision specification in type declarations. For instance, REAL*8 means an 8-byte
floating point data type. The REAL*8 datatype is not necessarily considered
equivalent to DOUBLE PRECISION, depending on the -wordsize setting. The Fortran 77
Standard allows a length specification only for CHARACTER data.

ftnchek supports the DOUBLE COMPLEX type specification for a complex quantity whose
real and imaginary parts are double precision. Mixed-mode arithmetic involving
single-precision complex with double-precision real data, prohibited under the
Standard, yields a double complex result.

Combined type declarations and data-statement-like initializers are accepted.
These have the form of a standard Fortran 77 type declaration, followed by a slash-
delimited list of constants like that used in a DATA statement. An example of the
syntax is
INTEGER N / 100 /
This bastard form of initializing declaration was not adopted in Fortran 90. Such
declarations should be written using the standard form described below, which is
accepted by ftnchek.

There is limited support for Fortran 90 attribute-based type declarations. This
style of declaration is distinguished by the use of a double colon (::) between the
list of attributes and the list of declared variables. The features supported may
be adequate for novice programmers, but are not yet sufficient for professional-
quality Fortran 90 programs. I hope to add support for more features in future
releases. I invite volunteers to assist in this task. See the ToDo file in the
source code distribution for details. The attributes currently accepted, besides
all the usual data types, are DIMENSION, EXTERNAL, INTRINSIC, PARAMETER, and SAVE.
The new form of declaration also allows assignment of values to the variables
declared. At present, the (LEN=value) form of specifying character lengths is also
accepted. Kind specifications, using (KIND=value) are parsed but are not
processed: all kinds are treated as default kind. Also, there is little checking
of these declarations beyond basic syntax.

Many commonly found nonstandard intrinsic functions are provided. See the
discussion of -intrinsic for a list of functions and how to control which ones are
recognized.

Argument checking is not tight for those nonstandard intrinsics that take arrays or
mixed argument types.

ftnchek permits the INCLUDE statement, which causes inclusion of the text of the
given file. The syntax is
INCLUDE 'filename'
This is compatible with Fortran 90. If the -source=vms-include option is given,
ftnchek follows VMS conventions with respect to this statement: it assumes a
default extension of .for if no filename extension is given, and allows the
qualifier /[NO]LIST following the filename, to control the listing of the included
file. There is no support for including VMS text modules.

In diagnostic output relating to items contained in include files, the location of
the error is specified by both its location in the include file and the location in
the parent file where the file was included.

ftnchek accepts PARAMETER statements which lack parentheses. These will be warned
about if the -f77=param-noparen flag is given.

ftnchek accepts PARAMETER definitions that involve intrinsic functions and
exponentiation by a non-integer exponent. Both of these cases are prohibited by
the Fortran 77 Standard, and will be warned about if the -f77=param-intrinsic flag
is given. If an intrinsic function value is a compile-time integer constant,
ftnchek will evaluate it. This allows better checking if the parameter is used in
declaring array sizes. Fortran 90 allows intrinsic functions in PARAMETER
definitions.

The intrinsic functions that are evaluated are:

ABS IABS DIM IDIM MAX
MAX0 MIN MIN0 MOD SIGN
ISIGN LEN ICHAR INDEX

The functions of integer arguments are evaluated only if the arguments are integer
constant expressions. (These may involve integer constants, parameters, and
evaluated intrinsic functions.) The function LEN is evaluated if its argument is
an expression involving only character constants and variables whose length is not
adjustable. The functions ICHAR and INDEX are evaluated only if the arguments are
character constants. ftnchek gives a warning if it needs the value of some
intrinsic function that is not evaluated.

NEW FEATURES

Here are the changes from Version 3.2 to Version 3.3:

1. Front-end has been rewritten for unlimited lookahead, eliminating the longstanding bug
that caused incorrect interpretation of statements whose ambiguity was not resolved in
the first line.

2. The -mkhtml option is now available in the MS-DOS version.

3. Added support for Fortran 90 pointer related syntax: ALLOCATE, DEALLOCATE, and NULLIFY
statements; the ALLOCATABLE, POINTER and TARGET attributes in type declarations; the
pointer assigment operator => and intrinsic functions ALLOCATED and ASSOCIATED; and
deferred-shape array declarations. At present these new syntax features are accepted
but not properly checked. This feature was added by Robert Landrito.

4. The -f77 and -f90 pointer option controlling warnings about ``Cray pointers'' has been
renamed to cray-pointer. The -f77=pointer option now instead controls warnings for
code containing Fortran 90 pointer-related syntax.

5. Re-implemented -mkhtml processing so it is now much faster on source files containing
many routines.

6. Changed the arrangement of the test directory so there is no longer any need to modify
the distribution in order to run the test suite (check.bat) under MS-DOS.

7. Fixed bug in reading numeric settings on command line when setting name abbreviated to
3 characters.

8. Fixed bug causing spurious warning for a GOTO referring to a labeled END statement
when the statement before END was a FORMAT.

9. New flag -f77=character to control warnings about extensions to the Fortran 77
character data type. Accompanying this new flag is support for Fortran 90 rules for
character variable declarations that evaluate to zero or negative length, allowing
them and treating negative length values as zero.

10. Fixed minor bug in printing of comments and blank lines following last END statement
in -list mode.

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