Updated: 2021/Apr/14


LINT(1)                     General Commands Manual                    LINT(1)

NAME
     lint - a C program verifier

SYNOPSIS
     lint [-abceFgHhPprTVvwxz] [-i | -nu] [-S | -s | -t | -Ac11]
          [-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 | -Ac11] -C library [-B directory]
          [-D name[=def]] [-d directory] [-I directory] [-MD] [-R old=new]
          [-U name] [-X id[,id ...]] [-Z cpparg] 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
     performs stricter type checking than traditional pre-C90 C compilers.
     The list of errors and warnings that 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, non-prototype functions called
     with varying numbers of arguments, non-prototype function calls that pass
     arguments of a type other than the type the function expects to receive,
     functions whose return values are not used, and calls to non-prototype
     functions not returning values that nevertheless 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) 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 but always exits successfully.  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.

     Options

     -Ac11         Allow features from C11, C99 and C90.

     -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 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.

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

     -e            Complain about unusual operations on enumtypes 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
                   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.

     -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 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            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 platforms of
                   C.

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

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

     -S            C9X mode.  Currently not fully implemented.

     -s            Strict ANSI C89/ISO C90 mode.  Issue warnings and errors
                   required by ISO C90, as opposed to traditional C.  Also do
                   not produce warnings for constructs which behave
                   differently in traditional C and ISO C90.  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 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.

     -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).

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

     /* 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
                 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
                 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
     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.

     LINT_KEEP_CPPOUT_ON_ERROR
                 If lint exits unsuccessfully, do no delete the output from
                 the C preprocessor, allowing for manual inspection.

     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.

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), lint(7)

AUTHORS
     Jochen Pohl (1995)
     Roland Illig (2021)

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.

NetBSD 9.99                     August 8, 2021                     NetBSD 9.99