> On Dec 11, 2015, at 2:41 AM, Gabriel Dos Reis <[email protected]> > wrote: > > Passing nothing at all is makes the most sense for a vigorous C++ support. > Passing a 1-byte that nothing can possibly read and makes sense of is an > unfortunate sub-optimal codegen.
I completely agree that psABI authors should specify that empty types are passed as nothing. John. > > On Thu, Dec 10, 2015 at 11:05 PM, Marc Glisse <[email protected] > <mailto:[email protected]>> wrote: > On Fri, 11 Dec 2015, Nelson, Clark wrote: > > It has come to my attention that GCC and clang generate incompatible code > for passing an argument of an empty class type. > > clang seems to completely ignore arguments and parameters of empty class > type -- which seems to make a certain amount of sense. > > OTOH, as far as I understand it, GCC effectively treats an empty class > equivalently to a class containing a single member with some character > type -- which also seems pretty reasonable. > > Should the C++ ABI come down on one side or the other of this question? > > See A-5 in https://mentorembedded.github.io/cxx-abi/cxx-closed.html > <https://mentorembedded.github.io/cxx-abi/cxx-closed.html> for some > historical discussion. > > This is really the sort of question a psABI should settle. But of course > the C language doesn't actually support a structure with no members, so > it's not too surprising if a psABI doesn't nail down what should happen > for this. > > Last time I raised this, psABI was also suggested: > http://sourcerytools.com/pipermail/cxx-abi-dev/2013-November/002627.html > <http://sourcerytools.com/pipermail/cxx-abi-dev/2013-November/002627.html> > > -- > Marc Glisse > > _______________________________________________ > cxx-abi-dev mailing list > [email protected] <mailto:[email protected]> > http://sourcerytools.com/cgi-bin/mailman/listinfo/cxx-abi-dev > <http://sourcerytools.com/cgi-bin/mailman/listinfo/cxx-abi-dev> > > _______________________________________________ > cxx-abi-dev mailing list > [email protected] > http://sourcerytools.com/cgi-bin/mailman/listinfo/cxx-abi-dev
_______________________________________________ cxx-abi-dev mailing list [email protected] http://sourcerytools.com/cgi-bin/mailman/listinfo/cxx-abi-dev
