Re: Document empty structures

[Mark Mitchell <mark at codesourcery dot com>]

On Mon, 2003-04-14 at 11:51, Richard Earnshaw wrote:
> > 
> > On Monday, April 14, 2003, at 11:20  AM, Mark Mitchell wrote:
> > 
> > > On Mon, 2003-04-14 at 11:17, Richard Earnshaw wrote:
> > >>
> > >>>> I'm pretty sure that the C++ language standard does not say that 
> > >>>> empty
> > >>>> structures have size 1 -- AFAIK it just says that they have 
> > >>>> non-zero size
> > >>>> (C++98 section 9, paragraph 3).
> > >>>
> > >>> Correct.  The C++ ABI says they have size 1.
> > >>
> > >> Even on a machine where STRUCTURE_SIZE_BOUNDARY != 8?  I would have
> > >> thought STRUCTURE_SIZE_BOUNDARY / BITS_PER_UNIT was a more sensible
> > >> definition.
> > >
> > > You are even more correct.  I forget what the exact calculation is, but
> > > it does indeed take this kind of thing into account.
> > 
> > Could someone provide a patch?

I checked in this patch, tested by rebuilding the docs.

-- 
Mark Mitchell <mark at codesourcery dot com>
CodeSourcery, LLC

2003-04-14  Mark Mitchell  <mark at codesourcery dot com>

	* doc/extend.texi (Empty Structures): Correct description of G++'s
	handling of these structures.

Index: extend.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/extend.texi,v
retrieving revision 1.133
diff -c -5 -p -r1.133 extend.texi
*** extend.texi	14 Apr 2003 02:55:27 -0000	1.133
--- extend.texi	15 Apr 2003 02:27:36 -0000
***************
*** 1,6 ****
! @c Copyright (C) 1988,1989,1992,1993,1994,1996,1998,1999,2000,2001,2002,
  @c 2003 Free Software Foundation, Inc.
  @c This is part of the GCC manual.
  @c For copying conditions, see the file gcc.texi.
  
  @node C Implementation
--- 1,6 ----
! @c Copyright (C) 1988,1989,1992,1993,1994,1996,1998,1999,2000,2001,2002, 2003,
  @c 2003 Free Software Foundation, Inc.
  @c This is part of the GCC manual.
  @c For copying conditions, see the file gcc.texi.
  
  @node C Implementation
*************** GCC permits a C structure to have no mem
*** 1370,1380 ****
  struct empty @{
  @};
  @end example
  
  The structure will have size zero.  In C++, empty structures are part
! of the language, and the language standard says they have size 1.
  
  @node Variable Length
  @section Arrays of Variable Length
  @cindex variable-length arrays
  @cindex arrays of variable length
--- 1370,1381 ----
  struct empty @{
  @};
  @end example
  
  The structure will have size zero.  In C++, empty structures are part
! of the language.  G++ treats empty structures as if they had a single
! member of type @code{char}.
  
  @node Variable Length
  @section Arrays of Variable Length
  @cindex variable-length arrays
  @cindex arrays of variable length