[Bug c++/22488] [4.1 Regression] C++ generates incorrect overlapping fields

["dberlin at dberlin dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-09-28 02:31 -------
Subject: Re:  [4.1 Regression] C++ generates incorrect
	overlapping fields

On Wed, 2005-09-28 at 02:06 +0000, mark at codesourcery dot com wrote:
> ------- Additional Comments From mark at codesourcery dot com  2005-09-28 02:06 -------
> Subject: Re:  [4.1 Regression] C++ generates incorrect overlapping
>  fields
> 
> dberlin at gcc dot gnu dot org wrote:
> 
> > However, the questions still remains, what is the offset supposed to be relative to?
> 
> The beginning of the type in which the field is contained, which I think
> means, in your parlance:

The parlance is that of GCC. I didn't invent DECL_CONTEXT :)

> 
> > The direct context, or the outermost containing type?
> 
> the "direct context".

Okay, then this is my bug, not yours :)
I'll change the summary in a moment.

> 
> In other words, if C has a field of type B at offset 32, and B has an
> field "f" with offset 16, then the offset of B::f relative to C is 48.
> (That's the only thing that makes any sense; otherwise, we'd have to
> make a copy of B every time it appeared as field in some other type.)

Well, yes, if you link everything together using a list like that, and
only store the offset in a shared field decl.
But if you had a nice vector of std::pair<offset, field>, you wouldn't
have to copy everything.  :)

> 
> 
> 



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22488