Path: utzoo!telly!ddsw1!mcdchg!rutgers!tut.cis.ohio-state.edu!BRL.MIL!phil
From: phil@BRL.MIL (Phil Dykstra)
Newsgroups: gnu.gcc.bug
Subject: constant expression folding problem?
Message-ID: <8810060857.aa03418@SPARK.BRL.MIL>
Date: 6 Oct 88 12:57:39 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 31

gcc 1.28  Sun 3/50  SunOS 3.5

The following code:
============================
struct test {
	char	s[32];
	int	i;
};
#define TEST_NULL	((struct test *)0)

char *foo = (char *)(TEST_NULL->s);

main()
{
}
============================
causes:
t.c:7: initializer for static variable is not constant

There is apparently something about that expression that the
constant folder can't reduce.  The Cray C compiler used
to die on this same sort of expression, but they fixed it.
I know of many other C compilers that accept it as well
(Sun, SGI, Alliant, Gould, Convex, Ardent, Pyramid, BSD Vax).
It would be nice if gcc could too.

- Phil

[The code may look terrible, but doing things sort of like this
is important for code that parses and fills in dynamic C data
structures!]