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