[K42-discussion] [PATCH] Added another ifdef->undef for offsetof which gets

[Paul H. Hargrove]

The C99 spec requires offsetof() to be #defined in <stddef.h>, which is 
the same place it requires NULL to be #defined.  For all recent gcc 
versions, stddef.h is in the complier-specific header directory that 
Michal mentions.

The Oct-2005  C++  draft standard says that <cstddef> has the same 
contents as C's <stddef>, with some exceptions.  Those exceptions limit 
what on what types one can invoke offsetof(), but the spec still says 
<cstddef> is the proper location for both NULL and offsetof().  As with 
<stddef.h>, g++ appears to ship <cstddef> in a compiler-specific 
subdirectory.

-Paul

Michal Ostrowski wrote:

>I'd like to emphasize that not only should this be in a header, it
>should be in a very low-level header; something that is going to be
>picked up everywhere.  Linux has such mechanisms by having compiler
>specific headers that are picked-up at a very low leve,
>
>  
>

-- 
Paul H. Hargrove                          PHHargrove at lbl.gov
Future Technologies Group                 
HPC Research Department                   Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory     Fax: +1-510-486-6900