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From: fnf@unisoft.UUCP (Fred Fish)
Newsgroups: net.micro.amiga
Subject: Another Lattice C bug (statement-less labels)
Message-ID: <25@unisoft.UUCP>
Date: Fri, 28-Feb-86 06:40:04 EST
Article-I.D.: unisoft.25
Posted: Fri Feb 28 06:40:04 1986
Date-Received: Sat, 1-Mar-86 22:45:10 EST
Reply-To: fnf@unisoft.UUCP ()
Organization: UniSoft Systems; Berkeley, CA
Lines: 47


Lattice C is currently the only C compiler that I know of (I tested
3 others) that accepts the following code fragment:

	main ()
	{
		goto labl;
	labl:
	}

All others required that the labl: be attached to a statement, even
if only the null statement, as in:

	main ()
	{
		goto labl;
	labl:	;
	}

Note that this second usage is consistent with K&R page 63:

	"It (a label) can be attached to any *statement* (emphasis mine)
	 in the same function as the goto."

And on page 204:

	"Any statement may be preceded by label prefixes ..."

	"A null statement is useful to carry a label just before the }
	 of a compound statement ..."

Also, from "A C Reference Manual" by Harbison and Steele, page 199:

	"A label cannot appear by itself but must always be attached
	 to a statement.  If it is desired to place a label by itself, for
	 example at the end of a compound statement, it may be attached
	 to a null statement."

This construct, a label without a statement, showed up in the amiga3d
program recently posted to usenet's net.sources.

-Fred

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Fred Fish    UniSoft Systems Inc, 739 Allston Way, Berkeley, CA  94710  USA
{ucbvax,dual}!unisoft!fnf	(415) 644 1230 		TWX 11 910 366-2145
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