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From: tps@sdchema.UUCP (Tom Stockfisch)
Newsgroups: net.lang.c,net.bugs.4bsd
Subject: Re: bug in cc (???)
Message-ID: <442@sdchema.sdchema.UUCP>
Date: Wed, 4-Sep-85 17:34:37 EDT
Article-I.D.: sdchema.442
Posted: Wed Sep  4 17:34:37 1985
Date-Received: Sun, 8-Sep-85 16:20:54 EDT
References: <502@lasspvax.UUCP>
Reply-To: tps@sdchema.UUCP (Tom Stockfisch)
Organization: Chemistry Dept, UC San Diego
Lines: 67
Xref: watmath net.lang.c:6282 net.bugs.4bsd:1744

[]
[Repost--  previous submission got mangled]

Todd Olson writes that the 4.2 C compiler can't handle
	
	int	n;
	struct S {
		int a;
		int b;
	} *X[2][2],
	.
	.
	.
	f( *X[n][0] );	/* cc complains on this line */

I think there are _many_ bugs in the way 4.2 handles passing whole structures.
Consider the following bug bite I received which prevents me from treating
complex numbers as primitives.  The gyst is that you can't immediately
access a member of a structure returned by a function.  Very frustrating.


/* C stuff trying to deal with complex numbers as primitives */

typedef struct {
	double re;
	double im;
} complex;

main()
{
	complex		topolar();
	double		mag;
	complex		c2;
	static complex	c1 = { 1.0, 2.0 };

/*###18 [cc] structure reference must be addressable%%%*/
	mag =	topolar(c1).re;			/* sure would be nice if I
						 * could do this
						 */

/*###21 [cc] structure reference must be addressable%%%*/
	mag =	( c2 = topolar(c1) ).re;	/* even this doesn't work */

	/* you have to break it into two separate statements--this works */
	c2 =	topolar(c1);
	mag =	c2.re;
}

complex
topolar( z )		/* convert z to polar form */
	complex	z;
{
	complex	polar;
	double	hypot(),	atan2();

	/* details not related to bug */
	polar.re =	hypot( z.re, z.im );
	polar.im =	atan2( z.im, z.re );
	return	polar;
}

/* end of program */

I sure hope 4.3 fixes this.

			--Tom Stockfisch
			  UCSD Chemistry