On Fri, 2014-10-03 at 11:41 -0700, Cary Coutant wrote: > > O. Then I was indeed wrong and defaulted does not impact ABI at all. > > At least that is one worry less for the abi checkers :) > > As Siva mentioned, it does in fact impact the ABI. A class with a > non-trivial destructor is not a POD, and affects the calling > convention, so the debugger needs to know the difference. C++ ABI > reference here: > > http://mentorembedded.github.io/cxx-abi/abi.html#return-value > > I've submitted a DWARF proposal to document the use of the > DW_AT_artificial attribute on a default copy constructor or > destructor.
Thanks for that reference. I was just stepping through gdb's gdbarch_return_in_first_hidden_param_p to understand why Siva's example did indeed seem to go wrong under GDB. That code is a little hairy with all the arch specific indirections, so I am happy I can stop now :) I can adjust my patch so that it does mark the declaration with DW_AT_artificial if it is DECL_COPY_CONSTRUCTOR_P or DECL_DESTRUCTOR_P. But maybe that is probably better done as a separate patch. Or does it make sense to mark all defaulted special function members as artificial instead of having a separate attribute for it? The (small) advantage of having a separate attribute is that the consumer knows whether it was explicitly defaulted. Thanks, Mark
