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From: bergsten@chalmers.UUCP (Per Bergsten)
Newsgroups: comp.lang.c
Subject: Re: Enum vs Define ===> BUG REPORT
Message-ID: <1834@chalmers.UUCP>
Date: Sun, 2-Aug-87 21:01:59 EDT
Article-I.D.: chalmers.1834
Posted: Sun Aug  2 21:01:59 1987
Date-Received: Wed, 5-Aug-87 05:02:06 EDT
References: <19913@ucbvax.BERKELEY.EDU> <447@umbc3.UMD.EDU> <24622@sun.uucp>
Reply-To: bergsten@chalmers.UUCP (Per Bergsten)
Organization: Dept. of CS, Chalmers, Sweden
Lines: 45

(Maybe this message should go to comp.bugs.something or sunspots).
The recent discussion about relative merits of the "enum" type made me
remember an obscure bug in PCC I discovered some time ago and (almost) forgot.

The following example should NOT be construed as a discredit to the idea
of enum. I am prepared to accept all the help the language/compiler can give;
I regard "enum" types as a small but not useless tool.

However, current implementations are lacking in quality.
-------------------------------------------------------------------------------
Consider:

	typedef enum { a=0, b=1, c=2 } t1;

	mine()
	{
		printf("mine: a=%d, b=%d, c=%d\n", a, b, c);
	}

	main()
	{
		typedef enum { b=0, c=1, d=2 } t2;

		mine();
		printf("main: b=%d, c=%d, d=%d\n", b, c, d);
		exit(0);
	}

On VAX/BSD 4.2 and on SUN-3/SunOs3.2 I obtain the following output:

	mine: a=0, b=1, c=2
	main: b=1, c=2, d=2
	        ^    ^

In my opinion this is wrong. I do confess I don't have access to a C-standard
document so my understanding of C is largely based on K&R and some 8 years of
practise, nevertheless I don't think that the compiler behaves correctly. At
the very least I would expect an error message if this is an illegal program.
Incidentally: lint (in verbose mode) only prints a warning that "b" and "c" are
redefined.
-------------------------------------------------------------------------------

	Per Bergsten				bergsten@chalmers.se
					........!mcvax!enea!chalmers!bergsten
				a.k.a		perb%holtec.uucp@chalmers