lint - a C program verifier
lint [ -abchnpuvx ] file ...
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 state-
ments, loops not entered at the top, automatic variables declared and not used, and logi-
cal 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
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.
p Attempt to check portability to the IBM and GCOS dialects of C.
h Apply a number of heuristic tests to attempt to intuit bugs, improve style, and
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.)
v Suppress complaints about unused arguments in functions.
x Report variables referred to by extern declarations, but never used.
a Report assignments of long values to int variables.
c Complain about casts which have questionable portability.
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
n Do not check compatibility against the standard library.
Exit(2) and other functions which do not return are not understood; this causes various
Certain conventional comments in the C source will change the behavior of lint:
at appropriate points stops comments about unreachable code.
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 miss-
ing n is taken to be 0.
shuts off strict type checking in the next expression.
turns on the -v option for the next function.
at the beginning of a file shuts off complaints about unused functions in this
/usr/lib/llib-lc declarations for standard functions
/usr/lib/llib-port declarations for portable functions
S. C. Johnson, Lint, a C Program Checker