107 lines
3 KiB
Text
107 lines
3 KiB
Text
.NH 1
|
|
How to make lint shut up
|
|
.PP
|
|
It can be very annoying having
|
|
.I lint
|
|
warn about questionable constructs of which the programmer already is
|
|
aware.
|
|
There should be a mechanism to give
|
|
.I lint
|
|
some extra information in the source code.
|
|
This could be done by introducing some special keywords, which
|
|
would have a special meaning to
|
|
.I lint.
|
|
This is a bad solution, because these keywords would cause existing
|
|
C compilers not to work on these programs.
|
|
A neater solution is to invent some comments having a special
|
|
meaning to
|
|
.I lint.
|
|
We call these comments
|
|
.I pseudocomments.
|
|
The pseudocomments have no meaning to existing C compilers, so
|
|
compilers will not have to be rewritten for C programs containing
|
|
the previously proposed special keywords.
|
|
The following pseudocomments are recognized by
|
|
.I lint.
|
|
.LP
|
|
\f(CW/* VARARGS\fIn\fP */\fR
|
|
.br
|
|
.in 5
|
|
The next function can be called with a variable number of arguments.
|
|
Only check the first \fIn\fP arguments.
|
|
The \fIn\fP must follow the word \f(CWVARARGS\fP immediately.
|
|
This pseudocomment is useful for functions like e.g. printf.
|
|
(The definition of the function printf should be preceded by
|
|
\f(CW/*\ VARARGS1\ */\fP.)
|
|
.in
|
|
.LP
|
|
\f(CW/* VARARGS */\fP
|
|
.br
|
|
.in 5
|
|
Means the same as \f(CW/* VARARGS0 */\fP.
|
|
.in
|
|
.LP
|
|
\f(CW/* ARGSUSED */\fP
|
|
.br
|
|
.in 5
|
|
Don't complain about unused arguments in the next function.
|
|
When we are developing a program we sometimes write functions of
|
|
which we do not yet use the arguments.
|
|
Because we do want to use
|
|
.I lint
|
|
on these programs, it is nice to have this pseudocomment.
|
|
.in
|
|
.LP
|
|
\f(CW/* NOTREACHED */\fP
|
|
.br
|
|
.in 5
|
|
.I Lint
|
|
makes no attempt to discover functions which never return,
|
|
although it \fIis\fP possible to find functions that don't return.
|
|
This would require a transitive closure with respect to the already
|
|
known \fInot-returning\fP functions; an inacceptable time consuming
|
|
process.
|
|
To make
|
|
.I lint
|
|
aware of a function that doesn't return, a call of this function
|
|
should be followed by the pseudocomment \f(CW/*\ NOTREACHED\ */\fP.
|
|
This pseudocomment can also be used to indicate that some case part
|
|
inside a switch (especially a default part) can't be reached.
|
|
The above mentioned cases of use of this pseudocomment are
|
|
examples.
|
|
The comment can be used just to indicate that some part of the
|
|
program can't be reached.
|
|
It sometimes is necessary to introduce an extra compound statement
|
|
to get the right effect.
|
|
See figure 9.
|
|
.KF
|
|
.DS B
|
|
.ft CW
|
|
if (cond)
|
|
/* if part */ ;
|
|
else {
|
|
error(); /* doesn't return */
|
|
/* NOTREACHED */
|
|
}
|
|
/* Without the compound else part, lint would assume
|
|
* the statement after the if statement to be NOTREACHED,
|
|
* instead of the end of the else part.
|
|
*/
|
|
.I
|
|
.DE
|
|
.ce
|
|
figure\ 9.
|
|
.R
|
|
.KE
|
|
.in
|
|
.LP
|
|
\f(CW/* LINTLIBRARY */\fP
|
|
.br
|
|
.in 5
|
|
All definitions following this comment are assumed to be library
|
|
definitions.
|
|
It shuts off complaints about unused functions and variables.
|
|
See also section 4.2.7 for how to use this comment for generating
|
|
lint libraries.
|
|
.in
|
|
.bp
|