LINT(1)                    OpenBSD Reference Manual                    LINT(1)

NAME
     lint - a C program verifier

SYNOPSIS
     lint [-abceghprvxzHFV] [-s|-t] [-i|-nu] [-Dname[=def]] [-Uname]
          [-Idirectory] [-Ldirectory] [-llibrary] [-ooutputfile] file ...
     lint [-abceghprvzHFV] [-s|-t] -Clibrary [-Dname[=def]] [-Idirectory]
          [-Uname] file ...

DESCRIPTION
     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 sym-
     bol 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 val-
     ues in some places and not in others, functions called with varying num-
     bers 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.  File-
     name 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 vari-
     ables.

     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 stan-
     dard 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 ig-
     nored.  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) out-
             puts 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 lan-
             guage.  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, im-
             prove 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 dif-
             ferently 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 key-
             words 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 run-
             ning lint on a subset of files comprising part of a larger pro-
             gram).

     -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 ex-
             ample, using a structure pointer without knowing its contents).

     -Clibrary
             Create a lint library with the name llib-llibrary.ln.  This li-
             brary 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, in-
             cluding libraries specified with the -l option, for mutual com-
             patibility.

     -Dname[=def]
             Define name for cpp(1), as if by a #define directive.  If no def-
             inition 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 pro-
             duce 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

     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 op-
                 tion for the next function).

     /* CONSTCOND */ or /* CONSTANTCOND */ or /* CONSTANTCONDITION */
                 suppress complaints about constant operands for the next ex-
                 pression.

     /* FALLTHRU */ or /* FALLTHROUGH */
                 suppress complaints about fall through to a case or default
                 labelled statement.  This directive should be placed immedi-
                 ately 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 warn-
                 ing 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 func-
                 tion 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 op-
     tion), 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 set-
                 ting 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 ALSO
     cc(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 declara-
     tion 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 3.5                     August 28, 1994                              4
