Re: [Cobolforgcc-devel] Re: %union

[Tim J. <te...@me...>]

Keisuke,

With accessor macros, you have to look at the macro to see what
is the underlying field. 

For example in gcc, TREE_USED(x) is common.used_flag. This is
particularly a problem if the same field is used for multiple
things, as it is in gcc (see tree.h). The debugger does not know
about accessor macros AFAIK so in the debugger you have to know
the real field names. static_flag has six different accessor
macros. 

Actually I am not really that against accessor macros, I used
them in treelang (sample front end) but mainly because I wanted
to make it as consistent with gcc as possible. 

The other thing is that having one giant union means that when
you do a p *x in gdb, the output goes for pages. On the other
hand just having cast into a single struct * makes it more
manageable. 

I am not against accessor macros if you want to use them in code
you write. It would not be a problem to define a %union I don't
think. Maybe the existing code would have to have casts added
though. I have a clean compile policy.

Tim Josling

Keisuke Nishida wrote:
> ...
> 
> > I don't like accessor macros really because you have to keep
> > looking up what actual fields they are accessing.
> 
> Could you explain what you mean here?
> 
> Thanks,
> Keisuke Nishida