Re: c/9058: structure with flexible array member: offsetof() != sizeof()

[Manfred Spraul <manfred@colorfullife.com>]

The following reply was made to PR c/9058; it has been noted by GNATS.

From: Manfred Spraul <manfred@colorfullife.com>
To: "Joseph S. Myers" <jsm28@cam.ac.uk>
Cc: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Subject: Re: c/9058: structure with flexible array member: offsetof() != sizeof()
Date: Fri, 27 Dec 2002 00:37:54 +0100

 Joseph S. Myers wrote:
 
 >On Thu, 26 Dec 2002, Manfred Spraul wrote:
 >
 >  
 >
 >>Thanks, I found the thread "C99 conformance bug in gcc-3.1" after filing 
 >>the bug report.
 >>What's the recommended approach to calculate the size for malloc calls? Is
 >>
 >>    struct a {int a; char b; short c[]; };
 >>
 >>    len = offsetof(struct a, c[nr_entries]);
 >>    
 >>
 >
 >You mean offsetof(struct a, c) + nr_entries * sizeof(short).
 >  
 >
 No, I meant what I wrote - is that valid? It would be less error prone, 
 e.g. if the type of the flexible array member is changed.
 linux kernel, i.e gcc portability across platforms.
 
 --
     Manfred