On 12/12/2015 01:42 PM, Marc Glisse wrote:
On Sat, 12 Dec 2015, Jakub Jelinek wrote:
On Sat, Dec 12, 2015 at 09:51:23AM -0500, Jason Merrill wrote:
On 12/11/2015 06:52 PM, H.J. Lu wrote:
On Thu, Dec 10, 2015 at 3:24 AM, Richard Biener
<richard.guent...@gmail.com> wrote:
On Wed, Dec 9, 2015 at 10:31 PM, Markus Trippelsdorf
<mar...@trippelsdorf.de> wrote:
On 2015.12.09 at 10:53 -0800, H.J. Lu wrote:
Empty C++ class is a corner case which isn't covered in psABI nor
C++ ABI.
There is no mention of "empty record" in GCC documentation. But
there are
plenty of "empty class" in gcc/cp. This change affects all
targets. C++ ABI
should specify how it should be passed.
About this patch, aren't we supposed to enable new C++ ABIs with
-fabi-version=42 (or whatever the next number is)?
Yes, the patch should definitely make this conditional on
abi_version_at_least.
There is a C++ ABI mailinglist, where you could discuss this issue:
http://sourcerytools.com/cgi-bin/mailman/listinfo/cxx-abi-dev
Yep. As long as the ABI doesn't state how to pass those I'd rather
_not_ change GCCs way.
It is agreed that GCC is wrong on this:
http://sourcerytools.com/pipermail/cxx-abi-dev/2015-December/002876.html
Yes, I think this is just a (nasty) bug on some GCC targets.
Well, the argument in that thread is weird, because C and C++ empty structs
are different, so it isn't surprising they are passed differently.
C++ makes those sizeof == 1, while C has them sizeof == 0.
Maybe it isn't surprising, but it isn't particularly helpful either. It
increases the number of places where the 2 are incompatible.
(I personally don't care about empty C structs)
Yep. The C standard doesn't have empty structs; it's a GNU extension.
But in any case argument passing can be compatible between C and C++, so
it really should be.
Jason
