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From: ado@elsie.UUCP
Newsgroups: net.bugs.4bsd
Subject: 4.1bsd lint and cc differ on syntax
Message-ID: <1126@elsie.UUCP>
Date: Sat, 21-Jul-84 18:06:30 EDT
Article-I.D.: elsie.1126
Posted: Sat Jul 21 18:06:30 1984
Date-Received: Mon, 23-Jul-84 02:11:44 EDT
Organization: NIH-LEC, Bethesda, MD
Lines: 64

Patient--
	/usr/src/cmd/cpp/cpp.c

Symptom--
	"lint" gives "syntax error" diagnostics on some programs that
	"cc" is happy with.

Repeat by--
	Pass this program through "cc" and "lint"; compare diagnostic output.

		#define NBPC	8	/* Number of Bits Per Character */

		main()
		{
		#if NBPC == 8
			return 0;
		#else
			return -1;
		#endif
		}

Diagnosis--
	"lint" does a "/lib/cpp -C ..." to do preprocessing.
	"cc" does a "/lib/cpp" without the -C.
	A line like
		#if 8 /* comment */ == 8
	(which is what the #if directive in the example above "expands" to)
	is syntactically correct if the comment is removed, and is a syntax
	error if the comment is allowed to stand.

Cure--
	Always remove comments in preprocessor directives.
	The changes below will do this, changing the "syntax error" you get
	when lint is run to one about "nonportability."

	ed /usr/src/cmd/cpp/cpp.c
	/passcom/a
	#ifndef OLDVERSION
	STATIC	int	inif;		/* we're in an #if directive */
	STATIC	int	oldpasscom;	/* saved passcom for duration of #if */
	#endif
	.
	/comment/a
	#ifndef OLDVERSION
				if (oldpasscom && inif)
					ppwarn("nonportable comment in #if");
	#endif
	.
	/yyparse/i
	#ifndef OLDVERSION
			inif = 1;
			oldpasscom = passcom;
			passcom = 0;
	#endif
	.
	/yyparse/a
	#ifndef OLDVERSION
			inif = 0;
			passcom = oldpasscom;
	#endif
	.
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