lint(1) lint(1)
NAME
lint - check C programs
SYNOPSIS
lint [option... ] file...
DESCRIPTION
lint detects features of C program files which are likely to be bugs,
non-portable, or wasteful. It also checks type usage more strictly
than the compiler. lint issues error and warning messages. Among the
things it checks for are unreachable code, loops not entered at the
top, automatic variables declared and not used, and logical expres-
sions whose value is constant. lint checks for functions that return
values in some places and not in others, functions called with varying
numbers or types of arguments, and functions whose values are not used
or whose values are used but none returned.
Arguments whose names end with .c are taken to be C source files.
Arguments whose names end with .ln are taken to be the result of an
earlier invocation of lint with either the -c or the -o option used.
The .ln files are analogous to .o (object) files that are produced by
the cc(1) command when given a .c file as input. Files with other suf-
fixes are warned about and ignored.
lint takes all the .c, .ln, and llib-lx.ln (specified by -l x) files
and processes them in their command line order. By default, lint
appends the standard C lint library llib-lc.ln to the end of the list
of files. When the -c option is used, the .ln and the llib-lx.ln files
are ignored. When the -c option is not used, the second pass of lint
checks the .ln and the llib-lx.ln list of files for mutual compatibil-
ity.
OPTIONS
The following options are used to suppress certain kinds of com-
plaints:
-a Suppress complaints about assignments of long values to variables
that are not long.
-b Suppress complaints about break statements that cannot be
reached.
-h Do not apply heuristic tests that attempt to intuit bugs, improve
style, and reduce waste.
-m Suppress complaints about external symbols that could be declared
static.
-u Suppress complaints about functions and external variables used
and not defined, or defined and not used. This option is suitable
for running lint on a subset of files of a larger program.
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-v Suppress complaints about unused arguments in functions.
-x Do not report variables referred to by external declarations but
never used.
The following options alter lint's behavior:
-l x Include the lint library llib-lx.ln
For example, you can include a lint version of the math library
llib-lm.ln by inserting -l m on the command line. This argument
does not suppress the default use of llib-lc.ln. These lint
libraries must be in the directory provided for them. This option
can be used to reference local lint libraries and is useful in
the development of multi-file projects. The sequence of the
specified -l options is significant, as the libraries are pro-
cessed in this sequence.
-n Do not check compatibility against the standard C lint library.
-p Attempt to check portability to other dialects of C Along with
stricter checking, this option causes all nonexternal names to be
truncated to eight characters and all external names to be trun-
cated to six characters and one case.
-s Produce one-line diagnostics only. lint occasionally buffers mes-
sages to produce a compound report.
-k Alter the behavior of /* LINTED [message] */ directives. Nor-
mally, lint will suppress warning messages for the code following
these directives. Instead of suppressing the messages, lint
prints an additional message containing the comment inside the
directive.
-y Specifies that the file being linted will be treated as if the
/* LINTLIBRARY */ directive had been used. A lint library is nor-
mally created by using the /* LINTLIBRARY */ directive.
-F Print pathnames of files lint normally prints the filename
without the path.
-c Cause lint to produce a .ln file for every .c file on the command
line. These .ln files are the product of lint's first pass only,
and are not checked for inter-function compatibility.
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-o x Cause lint to create a lint library with the name llib-lx.ln. The
-c option nullifies any use of the -o option. The lint library
produced is the input that is given to lint's second pass. The -o
option simply causes this file to be saved in the named lint
library. To produce a llib-lx.ln without extraneous messages, use
of the -x option is suggested. The -v option is useful if the
source files for the lint library are just external interfaces.
-V Write to standard error the product name and release.
-W file
Write a .ln file to file, for use by cflow(1).
-R file
Write a .ln file to file.lnt, for use by cxref(1).
-- If the first filename begins with a dash (-), the end of the
command-line options must be marked with --.
lint recognizes many cc options, such as -D, -U, -I, -L, -g, -O, -Xt,
-Xa, and -Xc, although -g and -O are ignored. If other options are
used, a warning is issued and they are ignored.
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Certain conventional comments in the C source can influence the
behavior of lint:
/* ARGSUSED n */
makes lint check only the first n arguments for usage; a missing
n is taken to be 0. This option acts like the -v option for the
next function.
/* CONSTCOND */ or /* CONSTANTCOND */ or /* CONSTANTCONDITION */
suppresses complaints about constant operands for the next
expression.
/* EMPTY */
suppresses complaints about a null statement consequent on an if
statement. This directive should be placed after the test expres-
sion, and before the semicolon. This directive is supplied to
support empty if statements when a valid else statement follows.
It suppresses messages on an empty else consequent.
/* FALLTHRU */ or /* FALLTHROUGH */
suppresses complaints about fall through to a case or default
labeled statement. This directive should be placed immediately
preceding the label.
/* LINTLIBRARY */
at the beginning of a file shuts off complaints about unused
functions and function arguments in this file. This is equivalent
to using the -v and -x options.
/ *LINTED [message] */
suppresses any intra-file warning except those dealing with
unused variables or functions. This directive should be placed on
the line immediately preceding where the lint warning occurred.
The -k option alters the way in which lint handles this direc-
tive. Instead of suppressing messages, lint will print an addi-
tional message, if any, contained in the comment. This directive
is useful in conjunction with the -s option for post-lint filter-
ing.
/* NOTREACHED */
at appropriate points stops comments about unreachable code. This
comment is typically placed just after calls to functions like
exit(2).
/* PRINTFLIKE n */
makes lint check the first (n-1) arguments as usual. The nth
argument is interpreted as a printf format string to check the
remaining arguments.
/* PROTOLIB n */
causes lint to treat function declaration prototypes as function
definitions if n is non-zero. This directive can only be used in
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conjunction with the /* LINTLIBRARY */ directive. If n is zero,
function prototypes will be treated normally.
/* SCANFLIKE n */
makes lint check the first (n-1) arguments as usual. The nth
argument is interpreted as a scanf format string to check the
remaining arguments.
/* VARARGS n */
suppresses the usual checking for variable numbers of arguments
in the following function declaration. The data types of the
first n arguments are checked; a missing n is taken to be 0. The
use of the ellipsis terminator (...) in the definition is sug-
gested in new or updated code.
lint produces its first output on a per-source-file basis. Complaints
regarding included files are collected and printed after all source
files have been processed, if -s is not specified. Finally, if the -c
option is not used, information gathered from all input files is col-
lected and checked for consistency. At this point, if it is not clear
whether a complaint stems from a given source file or from one of its
included files, the source filename will be printed followed by a
question mark.
The behavior of the -c and the -o options allows for incremental use
of lint on a set of C source files. Generally, one invokes lint once
for each source file with the -c option. Each of these invocations
produces a .ln file that corresponds to the file. After all the source
files have been separately run through lint, it is invoked once more
(without the -c option), listing all the .ln files with the needed
-l x options. This will print all the inter-file inconsistencies. This
scheme works well with make; it allows make to be used to lint only
the source files that have been modified since the last time the set
of source files were linted.
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NOTES
lint is tailored for the PCC C compiler. However, lint can also be
used to check programs that are to be compiled using the CES C com-
piler; but when it is so used, not all of the warnings which are out-
put will be meaningful.
LOCALE
The language of the message texts is governed by the environment vari-
able LCALL, LCMESSAGES or LANG.
When the default is set, the system behaves as if it were not interna-
tionalized, i.e. the message texts are in English. You must change one
of these variables in order to change the language of the message
texts.
Detailed information on the dependencies of the environment variables
and on internationalization in general can be found in the manual
"Programmer's Guide: Internationalization - Localization". Refer also
to environ(5) for information on setting the user environment.
FILES
LIBDIR
the directory where the lint libraries specified by the -lx
option must exist
LIBDIR/lint[12]
first and second passes
LIBDIR/llib-lc.ln
declarations for C Library functions (binary format; source is in
LIBDIR/llib-lc)
LIBPATH/llib-lm.ln
declarations for Math Library functions (binary format; source is
in LIBDIR/llib-lm)
TMPDIR/*lint*
temporary files
MPDIR
usually /var/tmp but can be redefined by setting the environment
variable TMPDIR [see tempnam in tempnam(3S)].
LIBDIR
usually /ccs/lib
LIBPATH
usually /usr/ccs/lib:/usr/lib
SEE ALSO
cc(1), cflow(1), cxref(1), lex(1), make(1), yacc(1).
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Chapter on "lint" in the "Guide to Tools for Programming in C".
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