Xref: utzoo comp.lang.c:30078 comp.unix.ultrix:3853
Newsgroups: comp.lang.c,comp.unix.ultrix
Path: utzoo!utgpu!watserv1!maytag!watdragon!watsol.waterloo.edu!tbray
From: tbray@watsol.waterloo.edu (Tim Bray)
Subject: bug in ultrix cc (possibly fixed now)
Message-ID: <1990Jul3.214603.2704@watdragon.waterloo.edu>
Sender: daemon@watdragon.waterloo.edu (Owner of Many System Processes)
Organization: University of Waterloo
Date: Tue, 3 Jul 90 21:46:03 GMT
Lines: 25

The following little fragment illustrates (I think) a horrible bug in ultrix
v2 cc.  OK, OK, I'm upgrading to ultrix v3 tomorrow, but for those still at
v2, and in the horrible eventuality that v3 doesn't fix this, her it is:

typedef struct 
{
  int	garbage;
  int	parameter;
} t;

main()
{
  t *pt;

  pt = (t*) malloc(sizeof(t));
  pt->parameter = -2;

  printf("%d\n", -6 * pt->parameter);
}

The bug is that the code prints -12, not 12.  It seems to have to do with
dereferencing structure members & multiplying by negative literals in
an arg list.  I dumped the .s code but don't know mips assembler well
enough to figure out what's up (it looks like jal (which is a macro?) is
doing something wrong).