Re: same-address mappings vs. relative pointers

On Dec5, 2013, at 15:44 , Andres Freund <andres@2ndquadrant.com> wrote:
> There might be some ugly compiler dependent magic we could do. Depending
> on how we decide to declare offsets. Like (very, very roughly)
> 
> #define relptr(type, struct_name, varname) union struct_name##_##varname{ \
>    type relptr_type; \
>    Offset relptr_off;
> }
> 
> And then, for accessing have:
> #define relptr_access(seg, off) \
>  typeof(off.relptr_type)* (((char *)seg->base_address) + off.relptr_off)
> 
> But boy, that's ugly.

Well, uglyness we can live with, especially if it's less ugly than the
alternatives. But I'm afraid is also unportable - typeof() is a GCC
extension, not a part of ANSI C, no?

best regards,
Florian Pflug