LINT(1) OpenBSD Reference Manual LINT(1)NAMElint - a C program verifier
SYNOPSISlint [-ceFfgHhprsVvxz] [-i | -nu] [-Dname[=def]] [-Idirectory]
[-Ldirectory] [-llibrary] [-ooutputfile] [-Uname] file ...
lint [-ceFfgHhprsVvz] -Clibrary [-Dname[=def]] [-Idirectory] [-Uname]
file ...
DESCRIPTIONlint 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 non-
existent 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:
-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.
-c Complain about casts which have questionable portability.
-Dname[=def]
Define name for cpp(1), as if by a #define directive. If no
definition is given, name is defined as 1.
-e Complain about unusual operations on enum-Types and combinations
of enum- and integer-Types.
-F Print pathnames of files. lint normally prints the filename
without the path.
-f For each warning or error, print the offending line of the
corresponding source code file.
-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 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.
-h Apply a number of heuristic tests to attempt to intuit bugs,
improve style, and reduce waste.
-Idirectory
Add directory to the list of directories in which to search for
include files.
-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.
-Ldirectory
Search for lint libraries in directory and directory/lint before
searching the standard place.
-llibrary
Include the lint library llib-llibrary.ln.
-n Do not check compatibility against the standard library.
-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.
-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.
-Uname Remove any initial definition of name for the preprocessor.
-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 Print the command lines constructed by the controller program to
run the C preprocessor and lint's first and second pass.
-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).
Input Grammar
lint's first pass reads standard C source files. lint recognizes the
following C comments as commands.
/* ARGSUSEDn */
Make 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] */
Suppress 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.
/* NORETURN */
Tell lint that the function will never return, which means
any code following a call to this function is unreachable.
This directive should be placed immediately preceding the
function.
/* NOTREACHED */
At appropriate points, inhibit complaints about unreachable
code. This comment is typically placed just after calls to
functions like exit(3).
/* PRINTFLIKEn */
Make 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 */
Cause 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 */
Make 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.
ENVIRONMENT
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.
FILES
/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
SEE ALSOcc(1), cpp(1), make(1)AUTHORS
Jochen Pohl
BUGS
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 4.9 September 5, 2007 OpenBSD 4.9
