Re: c/9762: Address of 'char' is incorrect.

[Andreas Schwab <schwab@suse.de>]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1038 bytes --]

The following reply was made to PR c/9762; it has been noted by GNATS.

From: Andreas Schwab <schwab@suse.de>
To: stephen.kennedy@havok.com
Cc: gcc-gnats@gcc.gnu.org, debian-gcc@lists.debian.org
Subject: Re: c/9762: Address of 'char' is incorrect.
Date: Thu, 20 Feb 2003 15:26:33 +0100

 stephen.kennedy@havok.com writes:
 
 |> #define TA char
 |> #define TB int
 |> #define TC int
 |> 
 |> void foobar(TA a, TB b, TC c);
 |> 
 |> int main()
 |> {
 |> 	foobar(1,2,3);
 |> 	return 0;
 |> }
 |> 
 |> void foobar(TA a, TB b, TC c)
 |> {
 |> 	printf("a == %i  claims %x\n", a, &a);
 |> 	printf("a == %i  really %x\n", (&b)[-1], (&b)-1);
 
 There is nothing in the C standard that requires that (char*)(&b-1) == &a.
 They are distinct objects, thus not comparable, and &b-1 by itself is
 already invalid.
 
 Andreas.
 
 -- 
 Andreas Schwab, SuSE Labs, schwab@suse.de
 SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
 Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
 "And now for something completely different."