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Re: [RFA] Enhance stabs reader to better deal with forward references
> On Fri, Feb 09, 2007 at 11:41:07AM -0800, Joel Brobecker wrote:
> > That's not where the fun stops, however. The code handling
> > const types looks like this:
> >
> > case 'k': /* Const qualifier on some type (Sun) */
> > type = read_type (pp, objfile);
> > type = make_cv_type (1, TYPE_VOLATILE (type), type,
> > dbx_lookup_type (typenums));
> > break;
> >
> > In our case, the "make_type" call ended up returning an undefined
> > type, and then we end up making a "const" copy of that undefined
> > type when calling "make_cv_type".
> >
> > The problem is that type 268 (our const type) is "complete", and
> > no future stabs entry will ammend it. So even though I some handling
> > for forward references of the kind above, this was not sufficient
> > because the type attached to our parameter was still an undefined
> > type.
> >
> > That's why I modified this part of the code to make the cv type
> > only when the target type was already defined. Otherwise, we give
> > up the "const" qualifier and reuse the target type instead. We
> > know that this target type will be fixed up later, so our parameter
> > will have a defined type, and we'll be able to print it. We end up
> > losing the "const" qualifier, but this is still way better than
> > not having any type at all.
>
> I really don't like this part. I don't understand it, either. Why is
> the CV type complete? When the non-qualified type is filled in, that
> should automatically fill this in, because of the CV ring. See the
> implementation of replace_type.
Thanks for the carefule review, Daniel.
I need to get back into this again. I am not familiar with the TYPE_CHAIN
ring so I didn't realize that replace_type should do the work. Looking
at the code in replace_type, there is something I don't understand:
/* The type length is not a part of the main type. Update it for each
type on the variant chain. */
chain = ntype;
do {
/* Assert that this element of the chain has no address-class bits
set in its flags. Such type variants might have type lengths
which are supposed to be different from the non-address-class
variants. This assertion shouldn't ever be triggered because
symbol readers which do construct address-class variants don't
call replace_type(). */
gdb_assert (TYPE_ADDRESS_CLASS_ALL (chain) == 0);
--> TYPE_LENGTH (ntype) = TYPE_LENGTH (type);
chain = TYPE_CHAIN (chain);
} while (ntype != chain);
Shouldn't it be "chain" instead of "ntype" here?
--
Joel