This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
Re: [RFA/dwarf-2] Fix for the null record problem
> > This is a followup on the thread that started with:
> >
> > http://sources.redhat.com/ml/gdb-patches/2004-02/msg00058.html
> >
> > The test proposed under that thread was dropped because an empty
> > struct is not legal C. However, it is legal in Ada, and I've seen
> > a message saying that it is also legal in C++.
>
> Seriously, I'd like to see a testcase that FAIL->PASS with this patch.
> Can somebody get a C++ testcase, at least?
>
> the patch looks sensible, but I would like to see the testcase go in
> at the same time, or we'll forget.
I tried to update one of the C++ testcase to include an empty struct,
but my C++ is completely rusty.
In class2.cc, I tried adding
struct empty_struct {};
Is that a struct type definition or a class definition. In any case,
GDB has no trouble at all printing the description of this type:
(gdb) ptype empty_struct
type = class empty_struct {
}
Does anybody know of a way to produce the "<incomplete type>" bug
with C++? Otherwise, there is my upcoming null_record.exp test,
but I need a bit more time before the first Ada testcase can be
committed.
> > I have found the source of the problem, and suggest the attached patch.
> > The problem was that GDB was mistakenly deducing that the empry record
> > was only a stub because of the lack of fields, and was therefore tagging
> > it with TYPE_FLAG_STUB. This is not correct. Instead, the right
> > approach, I believe, is to check for the DW_AT_declaration attribute.
> >
> > 2004-02-19 J. Brobecker <brobecker@gnat.com>
> >
> > * dwarf2read.c (read_structure_scope): Identify stub types
> > using the DW_AT_declaration attribute.
> >
> > tested on x86-linux. No regression. Fixes the testcase that was
> > proposed by Andrew (even though it is not legal C) and the Ada
> > case.
> >
> > OK to apply?
> >
> > Thanks,
> > --
> > Joel
> >
> > PS: BTW, my past 3 months of traveling will soon be over. The past
> > couple of weeks have been very hectic. I have noticed that there were
> > some messages directed at me to which I haven't answered yet. I am
> > really sorry. I have kept these messages and will try to answer them
> > soon.
> > Index: dwarf2read.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/dwarf2read.c,v
> > retrieving revision 1.130
> > diff -u -p -r1.130 dwarf2read.c
> > --- dwarf2read.c 28 Jan 2004 18:43:06 -0000 1.130
> > +++ dwarf2read.c 19 Feb 2004 13:58:42 -0000
> > @@ -3077,6 +3077,9 @@ read_structure_scope (struct die_info *d
> > TYPE_LENGTH (type) = 0;
> > }
> >
> > + if (dwarf2_attr (die, DW_AT_declaration, cu) != NULL)
> > + TYPE_FLAGS (type) |= TYPE_FLAG_STUB;
> > +
> > /* We need to add the type field to the die immediately so we don't
> > infinitely recurse when dealing with pointers to the structure
> > type within the structure itself. */
> > @@ -3213,11 +3216,6 @@ read_structure_scope (struct die_info *d
> > new_symbol (die, type, cu);
> >
> > do_cleanups (back_to);
> > - }
> > - else
> > - {
> > - /* No children, must be stub. */
> > - TYPE_FLAGS (type) |= TYPE_FLAG_STUB;
> > }
> >
> > processing_current_prefix = previous_prefix;
--
Joel