From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tim Hollebeek <tim@wfn-shop.princeton.edu>
To: law@cygnus.com
Cc: jbuck@Synopsys.COM, gavin@cygnus.com, cgw@alum.mit.edu, egcs@egcs.cygnus.com
Subject: Re: [PATCH] Fix for short-enums comparison bug
Date: Sun, 28 Feb 1999 22:53:00 -0000
Message-ID: <199902112216.RAA27319@wagner.Princeton.EDU>
References: <6271.918762821@hurl.cygnus.com>
X-SW-Source: 1999-02n/msg00404.html
Message-ID: <19990228225300.Sui36xW3moUcGzQZvtDVh07L0mEhunK3FD3Hnuu-CYA@z>

Jeffrey A Law writes ...
> 
> typedef enum {A=0, B, C, D} T;
> main(){
>   T x;
>   for (x=A; x<=D; ++x)
>     printf("%d ", (int)x);
>   putchar('\n');
> }
> 
> So the compiler could use a 2 bit unsigned field for x since the values for 
> enum T are 0, 1, 2, 3.  Other values will not fit and would be considered
> invalid.  Thus removing the test x <= D is technically valid for C++.  Right?

I seriously doubt it, since arguments to integer operators undergo
integral promotion.  The rules are different for C++, but I believe
the answer is no, since none of the standard integral types is allowed
to have only 2 bits.

---------------------------------------------------------------------------
Tim Hollebeek                           | "Everything above is a true
email: tim@wfn-shop.princeton.edu       |  statement, for sufficiently
URL: http://wfn-shop.princeton.edu/~tim |  false values of true."