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From: eppstein@garfield.columbia.edu (David Eppstein)
Newsgroups: comp.lang.c++,comp.lang.c
Subject: bug re unsigned to signed conversion?
Message-ID: <4626@columbia.UUCP>
Date: Sun, 24-May-87 15:39:29 EDT
Article-I.D.: columbia.4626
Posted: Sun May 24 15:39:29 1987
Date-Received: Sun, 24-May-87 21:44:37 EDT
Sender: nobody@columbia.UUCP
Organization: Columbia University CS Department
Lines: 24
Xref: mnetor comp.lang.c++:288 comp.lang.c:2232

The following program prints both messages.  I would expect it to print
neither, but at least the second message shouldn't happen.  The
generated C code for the two lines is essentially identical; no doubt
the second line and probably the first should have generated a cast to int.

This is on a Vax running 4.3; I don't know what version C++.
It occurred in a real example and took me much grief to track down.
I'm not convinced the C compiler is correct, which is why I'm also cross
posting to comp.lang.c.
            ------------
#include <stream.h>

int a = -1;
unsigned b = 2;

inline int conv() { return b; }

main()
{
    if (a > b) cout << "(int) -1 > (unsigned) 2 ???\n";
    if (a > conv()) cout << "(int) -1 > (int) (unsigned) 2 ????????\n";
}
-- 
David Eppstein, eppstein@cs.columbia.edu, Columbia U. Computer Science Dept.