lint

LINT(1)                    BSD General Commands Manual                   LINT(1)

NAME
     lint — a C program verifier

SYNOPSIS
     lint [-abceghprvwxzHFV] [-s | -t] [-i | -nu] [-D name[=def]] [-U name]
          [-I directory] [-d directory] [-L directory] [-MD] [-l library]
          [-o outputfile] [-B directory] [-X id[,id ...]] file ...
     lint [-abceghprvwzHFV] [-s | -t] -C library [-D name[=def]] [-U name]
          [-I directory] [-d directory] [-B directory] [-X id[,id ...]] file ...

DESCRIPTION
     The lint utility 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 lint utility
     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 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 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.  The lint utility also accepts special libraries specified with
     the -l option, which contain definitions of library routines and variables.

     The lint utility 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.  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)
             outputs 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      Do not 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      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 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.

     -S      C9X mode. Currently not fully implemented.

     -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).

     -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 never
             used.

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

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

     -C library
             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.

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

     -I directory
             Add directory to the list of directories in which to search for
             include files.

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

     -l library
             Include the lint library llib-llibrary.ln.

     -L directory
             Search for lint libraries in directory and directory/lint before
             searching the standard place.

     -F      Print pathnames of files.  The lint utility 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.

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

     -o outputfile
             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.

     -U name
             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.

     -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).

   Input Grammar
     lint's first pass reads standard C source files.  The lint utility
     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
             labelled 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.

     /* 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 warning 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(3) 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(3) 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 -l library 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 -l library
             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.

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 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.

BSD                               Mar 23, 2015                               BSD