lint - a C program checker
lint [-abchlnpuvx] [-Xdollar] [-wclass...] [-cpp] [-lx]
[-olib] [-dpath] [-MA] [-Msuboptions] [-Pppoptions]
[-stdn] [-XEnum] [-Qsuboptions] [-Ndnum] [-Nlnum] [-Nnnum]
[-Ntnum] [-Dname[=definition]] [-Idirectory] [-Uname]
file...
Any number of lint options may be used, in any order,
intermixed with file-name arguments. The following options
are used to suppress certain kinds of complaints: Suppress
complaints about assignments of long values to variables
that are not long. Suppress complaints about break statements
that cannot be reached. (Programs produced by lex or
yacc will often result in many such complaints). Do not
apply heuristic tests that attempt to intuit bugs, improve
style, and reduce waste. 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). Suppress
complaints about unused arguments in functions. Do not
report variables referred to by external declarations but
never used. Suppress complaints about the use of the dollar
sign ($) in variable names. Controls the reporting of
warning classes. All warning classes are active by
default. They can however, be individually activated by
including the appropriate option as part of the class
argument. For example, to report only declaration consistency
and Heuristic complaints, enter the following command:
lint -wA -wdh prog.c
In the preceding example, -wA deactivates all warnings
and -wdh activates the desired reports. The
following list describes available classes of warnings:
Non-ANSI features Comparisons with unsigned
values Declaration consistency Heuristic complaints
Suppresses the following messages: function prototype
not in scope and old style argument declaration.
Assignment of long values to variables that
are not long Null-effect code Unknown order of
evaluation Various portability concerns Return
statement consistency Proper usage of variables and
functions Deactivates all warnings Constants occurring
in conditionals Declarations that are never
used or defined. Obsolete features Function prototype
presence Detection of unreachable code Storage
capacity checks Equivalent to -u
The following options alter lint's behavior: Cause lint to
use /lib/cpp as its preprocessor instead of /usr/bin/cc.
Include additional lint library llib-lx.ln. For example,
you can include a lint version of the Math Library lliblm.ln
by inserting -lm on the command line. This argument
does not suppress the default use of llib-lc.ln. These
lint libraries must be in the assumed directory. This
option can be used to reference local lint libraries and
is useful in the development of multi-file projects. To
conform to the UNIX98 standard, a space character can be
inserted between the -l and the library identifier, x (for
example you can specify -l m to include a lint version of
the Math Library). Do not check compatibility against
either the standard or the portable lint library. Do not
check compatibility between files or the lint libraries.
Attempt to check portability to other dialects (IBM and
GCOS) of C. Along with stricter checking, this option
causes all non-external names to be truncated to eight
characters and all external names to be truncated to six
characters and one case. Cause lint to produce a file for
every file on the command line. These files are the product
of lint's first pass only, and are not checked for
inter-function compatibility. Cause lint to create a lint
library with the name llib-llib.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-llib.ln without extraneous
messages, use of the -x option is suggested. The -v option
is useful if the source file(s) for the lint library are
just external interfaces (for example, the way the file
llib-lc is written). These option settings are also available
through the use of "lint comments" (see below).
Cause lint to store the files created as a result of the
-o or -c option in the specified path. Enforce ANSI C
standard rules. The default lint preprocessing and parsing
mode is Extended C (K&R). ANSI mode prepends (adds at
the beginning) the standard ANSI library function prototypes
in place of the default extended-mode C library.
ANSI mode enforces a stricter interfile object reference/definition
linkage checking. This option also invokes
the -std1 C preprocessor option and defines the macro
_ANSI_C_SOURCE. Turn on or off specific ANSI features.
The following suboptions are supported: follow ANSI parsing
rules follow ANSI const array struct member bug follow
ANSI type compatibility rules follow ANSI type promotion
rules follow ANSI strict reference/definition rules follow
ANSI scoping rules for externs follow ANSI typing rules
The following rules govern the effects of the -M
option: If A is specified in a single instance of a
-M option (-MA), the checking for all of the suboptions
is turned on. If any of the suboptions are
specified in a single instance of a -M option when
A is also specified (-MAsuboptions), the checking
for the specified suboptions is turned off. If any
of the suboptions are specified twice in all
instances of the -M option, they cancel each other
out. If suboptions are specified in a single
instance of a -M option and A is not specified
(-Msuboptions), the checking for only the specified
suboptions is turned on.
For example, -MAt turns on all ANSI rules except
ANSI typing rules. Allows C preprocessor options
to be specified when executing the lint command.
For example, specifying -PV invokes the preprocessor
with the -V option specified. Directs the C
Preprocessor to generate the appropriate predefined
macros. The -std option causes the macro __STDC__=0
to be passed to the preprocessor; -std1 causes the
macro __STDC__=1 to be passed, and -std0 causes
__STDC__ to be undefined. The default is -std0. The
-std0 option is incompatible with the -M option. If
-std or -std1 are selected, the -MA ANSI parsing
rules are automatically selected. Specifies the
number (num) of errors lint accepts before terminating.
By default, lint terminates after encountering
30 errors.
The -Q option turns on checking for all common programming
techniques which might cause problems when moving from
32-bit systems to 64-bit systems. The -Q option disables
checking for other programming problems, so this switch
should be used only for migration checking.
Suboptions to -Q have the form -Qsuboptions. You can enter
more than one suboption with the -Q option, for example,
-QacP to suppress checking for pointer alignment problems,
problematic type casts, and function prototype checks,
respectively.
The following suboptions are available to suppress specific
categories of checking: Suppresses checking of
pointer alignment problems. Suppresses checking for problematic
type casts. (Overrides -QG option.) Suppresses
checking for format control strings in scanf and printf.
Suppresses checking for assignments of long values to
variables of a type other than long. Suppresses checking
for illegal combinations pointer and integer data types.
Suppresses checking for problematic sign extensions to
long Suppresses checking to see if a variable is used
before it is set. Suppresses checking to see if there is
constant truncation of longs in an assignment. Suppresses
checking to see if precision has been lost in field
assignment. Suppresses truncation message when casting to
char *. (Overridden by -Qc option.) Suppresses function
prototype checks. Suppresses checking for a problematic
combination of structure pointers. If structure checking
and cast checking are not suppressed then the casting of
differing structures and pointers to structures are
flagged if the structures differ in size and/or alignment
as described in the following two suboptions. Suppresses
warnings about casting a structure or structure pointer to
one of a different size. Takes effect only if c and S are
not specified on the command line. Suppresses warnings
about casting a structure or structure pointer to on of a
different alignment. Takes effect only if c and S are not
specified on the command line.
The -N option and its related suboptions allow you to
increase the size of various internal tables at run time
if the default values are not sufficient. All of the
tables are dynamically expandable; however, larger initial
values may improve run-time performance.
Suboptions to the -N option take the form -Nzx where z is
a suboption and x is an integer size. The following suboptions
are available: Use with -N to increase the initial
size of the symbol table. To increase the number of
entries, use -Nnnum to increase the number of entries. Use
a number greater than 1500, which is the default value.
The larger the number, the fewer collisions. As a rule of
thumb, use a number roughly twice the number of source
code lines. Use with -N when you encounter the error that
the dimension table has overflowed or is full. To increase
the number of base elements allocated to the members of
the dimension tables, use a number greater than 2000,
which is the default value. Use with -N when you
encounter the error stating that the parse tree limit has
been reached, "out of tree space; recompile with -Ntx
option with x greater than xxxx". Do not recompile; run
lint again on the module that generated the error using
-Ntyyyy with yyyy greater than the value in the error message.
Use with -N when you encounter the error stating
that the local type table limit has been reached, "out of
tree space; recompile with -Nlx option with x greater than
xxxx". Run lint again, do not recompile, on the module
that generated the error, using -Nlyyyy with yyyy greater
than the value in the error message.
The -D, -I, and -U options of cpp and the -g and -O
options of cc are also recognized as separate arguments.
The -g and -O options are ignored, but, by recognizing
these options, lint's behavior is closer to that of the cc
command. Other options are warned about and ignored. The
preprocessor symbol "lint" is defined to allow certain
questionable code to be altered or removed for lint.
Therefore, the symbol "lint" should be thought of as a
reserved word for all code that is planned to be checked
by lint.
The following lint directives, which appear as conventional
comments in the C source program, change the behavior
of lint: Prevents lint from warning against unused
function arguments (that is, turns on the -v option) for
the next function. When placed at the beginning of a
file, suppresses complaints about unused functions and
function arguments in this file. This is equivalent to
using the -v and -x options. This directive is used for
building lint libraries. Permits a standard prototype
checking library to be formed from header files by making
function prototype declarations appear as function definitions.
The /*LINTSTDLIB*/ directive implicitly activates
the functions of the /*NOTUSED*/ and /*LINTLIBRARY*/
directives to reduce warning noise levels. When placed in
a file, suppresses warnings about all used but undefined
external symbols and functions that are subsequently
encountered in the file. When placed at appropriate
points in a program (typically immediately following a
return, break, or continue statement), stops comments
about unreachable code. Note that lint does not recognize
the exit function and other functions that may not return.
When placed in a file, suppresses warnings about all
unused external symbols, functions, and function parameters
that are subsequently encountered in the file. This
directive is similar to the /*LINTLIBRARY*/ directive,
although /*NOTUSED*/ also applies to external symbols.
Suppresses the usual checking for variable numbers of
arguments in the following function declaration. The data
types of the first n arguments are checked; for instance,
if /*VARARGS2*/ is specified, lint checks only the first
two arguments. If n is not specified, it is interpreted as
a 0 (zero).
The lint utility produces its first output on a persource-file
basis. Complaints regarding included files are
collected and printed after all source files have been
processed. Finally, if the -c option is not used, information
gathered from all input files is collected 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 file name 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 file which
corresponds to the 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 -c option), listing all the files with
the needed -lx options. This will print all the inter-file
inconsistencies. This scheme works well with make(1); 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 run through lint.
The lint program checker attempts to detect features of
the C program files that are likely to be bugs, nonportable,
or wasteful. It also checks type usage more
strictly than the compilers. Among the things that are
currently detected are unreachable statements, loops not
entered at the top, automatic variables declared and not
used, and logical expressions whose value is constant.
Moreover, the usage of functions is checked to find 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 are taken to be C source
files. Arguments whose names end with are taken to be the
result of an earlier invocation of lint with either the -c
or the -o option used. The files are analogous to
(object) files that are produced by the cc command when
given a file as input. Files with other suffixes produce
warnings and are ignored.
The lint program checker will take all the llib-lx.ln
(specified by -lx) files and process them in their command
line order. It appends a lint library file to this list of
files, as follows: If the -p option is used, the portable
C lint library (llib-port.ln) is appended. If the -std or
-std1 option is used, the C standard lint library lliblcstd.ln)
is appended. If the -MA option is used, the
ANSI standard lint library (llib-lansi.ln) is appended.
Otherwise, the standard C lint library (llib-lc.ln) is
appended.
When the -c option is not used, the second pass of lint
checks this list of files for mutual compatibility. When
the -c option is used, the and the llib-lx.ln files are
ignored.
The exit(2), setjmp(3), and other functions that do not
return are not understood; this causes various lies.
The directory where the lint libraries specified by the
-lx option must exist. The directory where the lint
library sources are kept. First and second passes of
lint. Declarations for C library functions (binary format;
source is in llib-lc.c). Declarations for Curses
library functions (binary format; source is in
llib-lcrses.c). Declarations for C library functions
(binary format; source is in llib-lc.c). This is the
default library when the -std or -std1 command line
options are used with lint. Declarations for LEX library
functions (binary format; source is in llib-ll.c).
Declarations for Math library functions (binary format;
source is in llib-lm.c). Declarations for YACC library
functions (binary format; source is in llib-ly.c). Declarations
for the POSIX thread library functions (binary
format; source is in llib-lpthread.c). Declarations for
the POSIX real-time extensions library functions (binary
format; source is in llib-lrt.c). Declarations for
portable functions (binary format; source is in llibport.c).
Temporary files (default directory /usr/tmp).
Commands: cc(1), cpp(1), make(1)
lint(1)
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