https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108993
--- Comment #6 from Pablo Anigstein <panigstein at hotmail dot com> ---
(In reply to Jonathan Wakely from comment #3)
> (In reply to Pablo Anigstein from comment #2)
> > (In reply to Andrew Pinski from comment #1)
> > > Hmm,
> > > I noticed that since GCC 7 with -std=c++17, the b.x is not initialized at
> > > all. So the question I have is there a difference between C++ standards
> > > here?
>
> Derived is an aggregate in C++17, so b{} does aggregate init, not value init.
>
> > > Note the issue is we call Base's constructor after doing the zero
> > > initialization and the Base's constructor has a clobber in it which I
> > > think
> > > is correct.
>
> Maybe we should only clobber in the complete object constructor _ZN4BaseC1Ev
> and not in _ZN4BaseC2Ev.
>
> > > This is all front-end generation and not exactly related to the
> > > optimizations directly.
> >
> > There is no difference between C++ standards in this respect.
>
> Before C++11 there was no zero-init at all. Since C++11 the spec keeps
> changing, but the effects of zero-init are substantially the same. But
> Derived is an aggregate since C++17.
Thank you for the correction. I still think there is non-conformance for all
standards including C++17, I will post a modified example in a comment below.
>
> Aside: What does the comment "not a default constructor" mean in the
> testcase?
I guess he meant "user-provided".
