Updated: 2021/Apr/14

LINT(1)                     General Commands Manual                    LINT(1)

     lint - a C program verifier

     lint [-abceFgHhPprTVvwxz] [-i | -nu] [-S | -s | -t] [-B directory]
          [-D name[=def]] [-d directory] [-I directory] [-L directory] [-MD]
          [-l library] [-o outputfile] [-U name] [-X id[,id ...]] [-Z cpparg]
          file ...
     lint [-abceFgHhprTVvwz] [-S | -s | -t] -C library [-B directory]
          [-D name[=def]] [-d directory] [-I directory] [-MD] [-R old=new]
          [-U name] [-X id[,id ...]] [-Z cpparg] file ...

     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
     performs stricter type checking than does the C compiler.  The list of
     errors lint produces are enumerated in lint(7).

     lint runs the C preprocessor as its first phase, with the following
     preprocessor symbols defined to allow certain questionable code to be
     altered or skipped: __LINT__, lint, __lint, __lint__.  These symbols
     should therefore be thought of as reserved words 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

     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) 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 special input file name "-" causes lint to take input from standard
     input (until end of file) and process it as if it were a .c file.  If the
     -i flag is given and "-" is named as one of the input files, the -o flag
     must also be specified to provide an output file name.


     -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.

     -Bpath            Path to use when looking for the lint1 and lint2
                       binaries.  Defaults to /usr/libexec.

     -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.

     -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

     -c                Complain about casts which have questionable

     -Dname[=def]      Define name for cpp(1), as if by a #define directive.
                       If no definition is given, name is defined as 1.

     -ddirectory       Use directory instead of /usr/include as the default
                       place to find include files.

     -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.

     -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, trailing commas in enum
                       declarations, C++ -style "//" comments, 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 (alternative keywords with
                       leading underscores for both asm and inline are always

     -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.

     -MD               Pass -MD to cpp(1) causing cpp to create files
                       containing dependency information for each source file.

     -n                Do not check compatibility against the standard

     -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                Enable more portability warnings: Enum comparisons,
                       sign extension issues when assigning to wider integer
                       types, overflow warnings when assigning to wider types.

     -p                Attempt to check portability of code to other dialects
                       of C.

     -R old=new        Remap old directory prefixes to new for reproducible

     -r                In case of redeclarations report the position of the
                       previous declaration.

     -S                C9X mode.  Currently not fully implemented.

     -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                Treat _Bool as a data type that is incompatible with
                       all other scalar types.

     -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 alternative keywords
                       with leading underscores still are).

     -Uname            Remove any initial definition of name for the

     -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

     -w                Treat warnings as errors.

     -X id[,id ...]    Suppress error messages identified by the list of ids.
                       A list of messages and ids can be found in lint(7).

     -x                Report variables referred to by extern declarations,
                       but never used.

     -Z cpparg         Pass cpparg to cpp(1) directly.  Multiple -Z cppargs
                       can be passed in the order they are received.

     -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 */
                 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).

                 Suppress error messages about illegal bitfield types if the
                 type is an integer type, and suppress non-portable bitfield
                 type warnings.

                 Suppress complaints about constant operands for the next

     /* FALLTHRU */ or /* FALLTHROUGH */
                 Suppress complaints about fall through to a case or default
                 labeled 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.

     /* LINTEDn [comment] */ or /* NOSTRICTn [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.  The optional numeric argument suppresses
                 the specific numbered message instead of every message.  A
                 list of messages and ids can be found in lint(7).

     /* 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

     /* 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.

     CC          Location of the C compiler program.  Defaults to /usr/bin/cc.

     /usr/libexec/lint[12]         programs
     /usr/libdata/lint/llib-l*.ln  various prebuilt lint libraries
     /tmp/lint*                    temporaries

     cc(1), cpp(1), make(1), lint(7)

     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.

NetBSD 9.99                      Jan 12, 2021                      NetBSD 9.99