4.1bsd lint additions to catch "if (condition) ;"

[Arthur David Olson]

In article <389 at phri.UUCP>, roy at phri.UUCP (Roy Smith) writes:
> 
> 	Here's one that just got me:
> 
> 		if (sv > score);   <----- note extraneous semi-colon
> 			score = sv;

Here are additions to 4.1bsd's "lint" to catch constructs like that above.
Warnings are only produced if lint's "-h" flag is used.
Two files are involved.
In the description below, all code to be added appears between
"#ifndef OLDVERSION" and "#endif" directives.
As usual, the trade secret status of the code precludes a clearer posting.

First, additions to "lint.c".  Add this declaration just before the function
"ecode":

	#ifndef OLDVERSION
	char *	gripenull;
	#endif

. . .and, as the last statement in "ecode", add this:

	#ifndef OLDVERSION
		gripenull = 0;
	#endif

Second, additions to "cgram.y".  Just after the declaration of "fake",
add a declaration of "gripenull":

	#ifndef OLDVERSION
		extern char *	gripenull;
	#endif

In the code handling the "ifprefix statement" variant of a "statement"
add this code:

			|  ifprefix statement
				={ deflab($1);
	#ifndef OLDVERSION
				   gripenull = 0;
	#endif

In the code handling the "ifelprefix statement" variant of a "statement"
add this code:

			|  ifelprefix statement
				={  if( $1 != NOLAB ){
					deflab( $1 );
					reached = 1;
					}
	#ifndef OLDVERSION
					gripenull = 0;
	#endif

In the code handling the "SM" variant of a "statement" add this code:

			|   SM
	/* #ifndef OLDVERSION */
				={
				    if (hflag && gripenull != 0)
					werror(gripenull);
				 }
	/* #endif OLDVERSION */

In the code for "ifprefix"es, add this code:

				={  ecomp( buildtree( CBRANCH, $3, bcon( $$=getlab()) ) ) ;
	#ifndef OLDVERSION
				    gripenull = "bodyless if";
	#endif

And, finally, in the code for "ifelprefix"es, add this code:

				={  if( reached ) branch( $$ = getlab() );
				    else $$ = NOLAB;
	#ifndef OLDVERSION
				    gripenull = "bodyless else";
	#endif
--
Lint is an Oscar Madison trademark.
--
	UUCP: ..decvax!seismo!elsie!ado    ARPA: elsie!ado at seismo.ARPA
	DEC, VAX and Elsie are Digital Equipment and Borden trademarks