.TH LINT 1 
.UC
.SH NAME
lint \- a C program verifier
.SH SYNOPSIS
.B lint
[
.B \-abchnpuvx
]
file ...
.SH DESCRIPTION
.I Lint
attempts to detect features of the C program
.IR file s
which are
likely to be bugs, or non-portable, or wasteful.
It also checks the type usage of the program more strictly
than the compilers.
Among the things which are currently found are
unreachable statements,
loops not entered at the top,
automatic variables declared and not used,
and logical expressions whose value is constant.
Moreover, the usage of functions is checked to find
functions which return values in some places and not in others,
functions called with varying numbers of arguments,
and functions whose values are not used.
.PP
By default, it is assumed that all the
.IR file s
are to be loaded together; they are checked for
mutual compatibility.
Function definitions for certain libraries are available to
.IR lint ;
these libraries are referred to by a
conventional name,
such as `\-lm', in the style of
.IR ld (1).
.PP
Any number of the options in the following list
may be used.
The
.SM
.BR \-D "\*S,"
.SM
.BR \-U "\*S,"
and
.SM
.B \-I
options of
.IR cc (1)
are also recognized as separate arguments.
.TP
.B p
Attempt to check portability to the
.I IBM
and
.I GCOS
dialects of C.
.TP
.B h
Apply a number of heuristic tests to attempt to
intuit bugs, improve style, and reduce waste.
.TP
.B b
Report
.I break
statements that cannot be reached.
(This is not the default because, unfortunately,
most
.I lex
and many
.I yacc
outputs produce dozens of such comments.)
.TP
.B v
Suppress complaints about unused arguments in functions.
.TP
.B x
Report variables referred to by extern declarations,
but never used.
.TP
.B a
Report assignments of long values to int variables.
.TP
.B c
Complain about casts which have questionable portability.
.TP
.B u
Do not complain about functions and variables used and not
defined, or defined and not used (this is suitable for running
.I lint
on a subset of files out of a larger program).
.TP
.B n
Do not check compatibility against the standard library.
.PP
.IR Exit (2)
and other functions which do not return
are not understood; this causes various lies.
.PP
Certain conventional comments in the C source
will change the behavior of
.IR lint :
.TP
/*NOTREACHED*/
at appropriate points
stops comments about unreachable code.
.TP
.RI /*VARARGS n */
suppresses
the usual checking for variable numbers of arguments
in the following function declaration.
The data types of the first
.I n
arguments are checked;
a missing
.I n
is taken to be 0.
.TP
/*NOSTRICT*/
shuts off strict type checking in the next expression.
.TP
/*ARGSUSED*/
turns on the
.B \-v
option for the next function.
.TP
/*LINTLIBRARY*/
at the beginning of a file shuts off complaints about
unused functions in this file.
.SH FILES
.ta 2i
/usr/lib/lint[12]	programs
.br
/usr/lib/llib-lc	declarations for standard functions
.br
/usr/lib/llib-port	declarations for portable functions
.SH SEE ALSO
cc(1)
.br
S. C. Johnson,
.I Lint, a C Program Checker
.SH BUGS
On nonseparate I/D machines, \fIlint\fP is extremely slow because
\fI/usr/lib/lint1\fP generates a huge number of overlay traps.
.PP
The standard
.I lint
library, /usr/lib/llib-lc, has been changed to correspond to reality (i.e.
the system source).  This will cause numerous complaints about programs which
were previously thought to be fluff-free.