lint - a C program verifier
lint [-abceghprvxzHFV] [-s|-t] [-i|-nu] [-Dname[=def]]
[-Uname]
[-Idirectory] [-Ldirectory] [-llibrary] [-ooutputfile]
file ...
lint [-abceghprvzHFV] [-s|-t] -Clibrary [-Dname[=def]]
[-Idirectory]
[-Uname] file ...
lint attempts to detect features of the named C program
files that are
likely to be bugs, non-portable, or wasteful. It also performs stricter
type checking than the C compiler. lint runs the C preprocessor as its
first phase, with the preprocessor symbol lint defined to
allow certain
questionable code to be altered or skipped by lint. Therefore, this symbol
should be thought of as a reserved word for all code
that is to be
checked by lint.
Among the possible problems that are currently noted are unreachable
statements, loops not entered at the top, variables declared
and not
used, and logical expressions with constant values. Function calls are
checked for inconsistencies, such as calls to functions that
return values
in some places and not in others, functions called with
varying numbers
of arguments, function calls that pass arguments of a
type other
than the type the function expects to receive, functions
whose values are
not used, and calls to functions not returning values that
use the nonexistent
return value of the function.
Filename arguments ending with .c are taken to be C source
files. Filename
arguments with names ending with .ln are taken to be
the result of
an earlier invocation of lint, with either the -i, -o, or -C
option in
effect. The .ln files are analogous to the .o (object)
files produced by
cc(1) from .c files. lint also accepts special libraries
specified with
the -l option, which contain definitions of library routines
and variables.
lint takes all the .c, .ln, and llib-llibrary.ln (lint library) files and
processes them in command-line order. By default, lint appends the standard
C lint library (llib-lc.ln), if it exists, to the end
of the list of
files. When the -i option is used, the .ln files are ignored. Also,
when the -o or -i options are used, the llib-llibrary.ln
files are ignored.
When the -i option is omitted the second pass of
lint checks this
list of files for mutual compatibility. At this point, if a
complaint
stems not from a given source file, but from one of its included files,
the source filename will be printed followed by a question
mark.
The options are as follows:
-a Report assignments of long values to variables that
are not long.
-aa Additional to -a, report all assignments of integer
values to
other integer values which cause implicit narrowing
conversion.
-b Report break statements that cannot be reached.
This is not the
default because, unfortunately, most lex(1) and many
yacc(1) outputs
produce many such complaints.
-c Complain about casts which have questionable portability.
-e Complain about unusual operations on enum-Types and
combinations
of enum- and integer-Types.
-g Don't print warnings for some extensions of gcc(1)
to the C language.
Currently these are nonconstant initializers
in automatic
aggregate initializations, arithmetic on pointer to
void, zero
sized structures, subscripting of non-lvalue arrays,
prototypes
overriding old style function declarations and long
long integer
types. The -g flag also turns on the keywords asm
and inline
(alternate keywords with leading underscores for
both asm and
inline are always available).
-h Apply a number of heuristic tests to attempt to intuit bugs, improve
style, and reduce waste.
-i 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 compatibility between functions.
-n Do not check compatibility against the standard library.
-p Attempt to check portability of code to other dialects of C.
-r In case of redeclarations report the position of the
previous
declaration.
-s Strict ANSI C mode. Issue warnings and errors required by ANSI
C. Also do not produce warnings for constructs
which behave differently
in traditional C and ANSI C. With the -s
flag,
__STRICT_ANSI__ is a predefined preprocessor macro.
-t Traditional C mode. __STDC__ is not predefined in
this mode.
Warnings are printed for constructs not allowed in
traditional C.
Warnings for constructs which behave differently in
traditional C
and ANSI C are suppressed. Preprocessor macros describing the
machine type (e.g., sun3) and machine architecture
(e.g., m68k)
are defined without leading and trailing underscores. The keywords
const, volatile and signed are not available
in traditional
C mode (although the alternate keywords with leading
underscores
still are).
-u Do not complain about functions and external variables used and
not defined, or defined and not used (this is suitable for running
lint on a subset of files comprising part of a
larger program).
-v Suppress complaints about unused arguments in functions.
-x Report variables referred to by extern declarations,
but never
used.
-z Do not complain about structures that are never defined (for example,
using a structure pointer without knowing its
contents).
-Clibrary
Create a lint library with the name
llib-llibrary.ln. This library
is built from all .c and .ln input files. After all global
definitions of functions and variables in these
files are written
to the newly created library, lint checks all input
files, including
libraries specified with the -l option, for
mutual compatibility.
-Dname[=def]
Define name for cpp(1), as if by a #define directive. If no definition
is given, name is defined as 1.
-Idirectory
Add directory to the list of directories in which to
search for
include files.
-llibrary
Include the lint library llib-llibrary.ln.
-Ldirectory
Search for lint libraries in directory and
directory/lint before
searching the standard place.
-F Print pathnames of files. lint normally prints the
filename
without the path.
-H If a complaint stems from an included file lint
prints the name
of the included file instead of the source file name
followed by
a question mark.
-ooutputfile
Name the output file outputfile. The output file
produced is the
input that is given to lint's second pass. The -o
option simply
saves this file in the named output file. If the -i
option is
also used the files are not checked for compatibility. To produce
a llib-llibrary.ln without extraneous messages,
use of the
-u option is suggested. The -v option is useful if
the source
file(s) for the lint library are just external interfaces.
-Uname Remove any initial definition of name for the preprocessor.
-V Print the command lines constructed by the controller program to
run the C preprocessor and lint's first and second
pass.
Input Grammar [Toc] [Back]
lint's first pass reads standard C source files. lint recognizes the
following C comments as commands.
/* ARGSUSEDn */
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 */
suppress complaints about constant operands for
the next expression.
/* FALLTHRU */ or /* FALLTHROUGH */
suppress complaints about fall through to a case
or default
labelled statement. This directive should be
placed immediately
preceding the label.
/* LINTLIBRARY */
At the beginning of a file, mark all functions
and variables
defined in this file as used. Also shut off
complaints about
unused function arguments.
/* LINTED [comment] */ or /* NOSTRICT [comment] */
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.
/* LONGLONG */
Suppress complaints about use of long long integer types.
/* NOTREACHED */
At appropriate points, inhibit complaints about
unreachable
code. (This comment is typically placed just
after calls to
functions like exit(3)).
/* PRINTFLIKEn */
makes lint check the first (n-1) arguments as
usual. The n-
th argument is interpreted as a printf format
string that is
used to check the remaining arguments.
/* PROTOLIBn */
causes lint to treat function declaration prototypes as function
definitions if n is non-zero. This directive can only
be used in conjunction with the /* LINTLIBRARY
*/ directive.
If n is zero, function prototypes will be treated normally.
/* SCANFLIKEn */
makes lint check the first (n-1) arguments as
usual. The n-
th argument is interpreted as a scanf format
string that is
used to check the remaining arguments.
/* VARARGSn */
Suppress 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 behavior of the -i 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 -i option. Each of these invocations produces
a .ln file that corresponds to the .c file, and prints all
messages that
are about just that source file. After all the source files
have been
separately run through lint, it is invoked once more (without the -i option),
listing all the .ln files with the needed -llibrary
options. This
will print all the inter-file inconsistencies. This scheme
works well
with make(1); it allows make(1) to be used to lint only the
source files
that have been modified since the last time the set of
source files were
linted.
LIBDIR the directory where the lint libraries specified
by the
-llibrary option must exist. If this environment variable is
undefined, then the default path
/usr/libdata/lint will be
used to search for the libraries.
TMPDIR usually the path for temporary files can be redefined by setting
this environment variable.
/usr/libexec/lint[12] programs
/usr/libdata/lint/llib-lposix.ln prebuilt POSIX C lint library
/usr/libdata/lint/llib-lstdc.ln prebuilt ANSI/ISO C lint
library
/tmp/lint* temporaries
cc(1), cpp(1), make(1)
Jochen Pohl
The routines exit(3), longjmp(3) and other functions that do
not return
are not understood; this causes various incorrect diagnostics.
Static functions which are used only before their first extern declaration
are reported as unused.
Libraries created by the -o option will, when used in later
lint runs,
cause certain errors that were reported when the libraries
were created
to be reported again, and cause line numbers and file names
from the
original source used to create those libraries to be reported in error
messages. For these reasons, it is recommended to use the
-C option to
create lint libraries.
OpenBSD 3.6 August 28, 1994
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