Autah-cs.156
net.bugs.v7
utzoo!decvax!duke!chico!harpo!utah-cs!lepreau
Wed Jan  6 12:17:38 1982
Re: sizeof type botch (utzoo.1248)
We decided that this is a compiler bug and fixed it.  What prompted this
rash action is that the "bug" has disastrous consequences for a
canonical Unix code sequence:

/* Read a "record" (struct), then back up to the beginning of it */
/* in order to update it in place.				 */
     read(fd, (char *) &record, sizeof record);
     lseek(fd, (long) -(sizeof record), 1);

Because the sizeof expr was unsigned, you seek to a very large positive number!
(Of course one can write:  -((long) sizeof record) but it's easy to forget...)
The obvious negative aspect of this change is that sizeof (objects > 32K)
doesn't work, but we think that's the lesser evil.  One can always do
(sizeof(array[0]) * ARRAYLEN).
-------------
The fix follows, to c01.c.
43c43
type = UNSIGN;
---
> 		t1->type = INT;		/* was UNSIGN;	 J.Lepreau 5/81 */
-------------

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