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Re: [PATCH v2][PR gdb/19893] Fix handling of synthetic C++ references
- From: Martin Galvan <martin dot galvan at tallertechnologies dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: gdb-patches <gdb-patches at sourceware dot org>
- Date: Tue, 24 May 2016 11:07:12 -0300
- Subject: Re: [PATCH v2][PR gdb/19893] Fix handling of synthetic C++ references
- Authentication-results: sourceware.org; auth=none
- References: <1464019228-11131-1-git-send-email-martin dot galvan at tallertechnologies dot com> <04d07644-c6ed-88ae-f1de-cba46e875f2d at redhat dot com>
Thanks for the answer!
On Tue, May 24, 2016 at 7:46 AM, Pedro Alves <palves@redhat.com> wrote:
> ... I still don't know what to think of this -- I simply don't understand it whether
> you're doing this because it makes sense, or because doing otherwise would be hard
> to do?
>From a consistency point of view, it's probably not the right thing.
All of the synthetic pointer cases I've tested always show "<synthetic
pointer>" instead of "@address".
As for how to fix it, yeah, it would be hard. Or at least I don't know
how to do it off the top of my head. I'd have to make value_addr not
return a not_lval when passing it a synthetic ref, which I'm not sure
it's right either.
I *could*, however, manually call
value->location.computed.funcs->check_synthetic_pointer in
generic_val_print_ref instead of using value_bits_synthetic_pointer,
thus avoiding the check for lval_computed. But that's a bit ugly IMHO.
> - Can you show an example output? (set print object on/off, etc. whatever might be
> handy to clearly explain that that is about).
> Pictures are really worth a thousand words. :-)
Sure:
(gdb) set print object off
(gdb) print ref
$3 = (S &) <synthetic pointer>: {
a = 0,
b = 1,
c = 2
}
(gdb) set print object on
(gdb) print ref
$4 = (S &) @0x601038: {
a = 0,
b = 1,
c = 2
}
Here, 0x601038 is the address of the structure 'ref' is referencing.
This is consistent with the output for non-synthetic references, where
the referenced value's address is shown.
> - Is this covered by any testcase? I looked for "object" in the whole patch and
> didn't seem to find it.
Not that I know of. Should I add a test for this to implref-struct?