NAME

lint − a C program verifier

SYNOPSIS

lint [ −abchnpuvx ] file ... 

DESCRIPTION

Lint attempts to detect features of the C program files 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. 

By default, it is assumed that all the files are to be loaded together; they are checked for mutual compatibility.  Function definitions for certain libraries are available to lint; these libraries are referred to by a conventional name, such as ‘−lm’, in the style of ld(1). Arguments ending in .ln are also treated as library files.  To create lint libraries, use the −C option:

lint −Cfoo files . . . 

where files are the C sources of library foo.  The result is a file llib-lfoo.ln in the correct library format suitable for linting programs using foo. 

Any number of the options in the following list may be used.  The −D, −U, and −I options of cc(1) are also recognized as separate arguments.

-a Report assignments of long values to int variables. 

-b Report break statements that cannot be reached.  (This is not the default because, unfortunately, most lex and many yacc outputs produce dozens of such comments.) 

-c Complain about casts which have questionable portability. 

-h Apply a number of heuristic tests to attempt to intuit bugs, improve style, and reduce waste. 

-mtarget This switch is passed to the C preprocessor, and ensures that machine-dependent include files for machine target are used. 

-M Do not complain about multiply-defined procedures.  This switch is useful, for example, when linting a library against its own lint library generated with -C. 

-n Do not check compatibility against the standard library. 

-p Attempt to check portability to the IBM and GCOS dialects of C. 

-S Apply stricter Sprite coding standards.  With this option, “++” and “--” are disallowed as side effects inside other expressions, assignment is not permitted inside if conditionals, and the bodies of ifs and other compound statements must be enclosed in braces. 

-u Do not complain about functions and variables used and not defined, or defined and not used (this is suitable for running lint on a subset of files out 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 (e.g.  using a structure pointer without knowing its contents.). 

Exit(2) and other functions which do not return are not understood; this causes various lies.

Certain conventional comments in the C source will change the behavior of lint:

/∗NOTREACHED∗/
at appropriate points stops comments about unreachable code.

/∗VARARGSn∗/
suppresses 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. 

/∗NOSTRICT∗/
shuts off strict type checking in the next expression.

/∗ARGSUSED∗/
turns on the −v option for the next function. 

/∗LINTLIBRARY∗/
at the beginning of a file shuts off complaints about unused functions in this file.

AUTHOR

S.C. Johnson.  Lint library construction implemented by Edward Wang. 

FILES

/usr/lib/lint/lint[12]programs
/usr/lib/lint/llib-lc.lndeclarations for standard functions
/usr/lib/lint/llib-lchuman readable version of above
/usr/lib/lint/llib-port.lndeclarations for portable functions
/usr/lib/lint/llib-porthuman readable . . . 
llib-l∗.lnlibrary created with −C

SEE ALSO

cc(1)
S. C. Johnson, Lint, a C Program Checker

BUGS

There are some things you just can’t get lint to shut up about. 

/∗NOSTRICT∗/ is not implemented in the current version (alas). 

Sprite version 1.0  —  March 17, 1986