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, to be non-portable, or to be wasteful. It also per-
     forms stricter type checking then does the C compiler.  lint runs the C
     preprocessor as its first phase, with the preprocessor symbol lint de-
     fined 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 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 ef-
     fect. 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) 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 giv-
     en source file, but from one of its included files, the source filename
     will be printed followed by a question mark.

     Options

     -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 conver-
                 sion.

     -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 combina-

                 tions 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 au-
                 tomatic aggregate initializations, arithmetic on pointer to
                 void, zero sized structures, subscripting of non-lvalue ar-
                 rays, 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 un-
                 derscores 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 AN-
                 SI C.  Also do not produce warnings for constructs which be-
                 have 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 tradition-
                 al 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 archi-
                 tecture (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 key-
                 words 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 nev-
                 er used.

     -z          Do not complain about structures that are never defined (for
                 example, using a structure pointer without knowing its con-
                 tents).

     -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 in-
                 put 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 be-
                 fore 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 compatibil-
                 ity.  To produce a llib-llibrary.ln without extraneous mes-
                 sages, 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-l*.ln  various prebuilt lint libraries
     /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 2.6                     August 28, 1994                              5