On Wed, Sep 22, 2021 at 8:00 AM Jens Maurer via Liaison <
liaison_at_[hidden]> wrote:

> On 21/09/2021 23.15, Uecker, Martin wrote:
> > Am Dienstag, den 21.09.2021, 23:02 +0200 schrieb Jens Maurer:
> >> On 21/09/2021 20.54, Uecker, Martin via Liaison wrote:
> >>> Am Dienstag, den 21.09.2021, 10:06 -0700 schrieb Ryan McDougall:
> >>>> It should *not* be ignorable in my opinion, because ignoring runs
> counter
> >>>> to the purpose of the feature
> >>>
> >>> You mean that a compiler should not be allowed to ignore it
> >>> when in "enforcing" mode and that a compiler that does not
> >>> support this feature should fail during compilation? Correct?
> >>
> >> I think this "ignorable" discussion is misguided.
> >>
> >> As far as I understand, it is explicitly desired that all
> >> conforming implementations diagnose syntactically ill-formed
> >> precondition / postcondition expressions.
> >
> > But this is completely independent of
> > the choice of the syntax.
>
> Yes.
>
> > Only for old compilers (i.e. then non-conforming to
> > a new standard) it matters:
>
> Every new feature that comes with syntax changes is
> likely unparsable for older compilers.
> C99 VLAs, for example, are just errors in C89.
>
> I don't understand why we'd want to make a special
> effort to accommodate older compilers for contracts
> in particular, a major new language feature.
>

+1.
Please explain to me why we care in this specific context.
Never have we promised that C++N code would do something sensible when
compiled as C++(N-1)

>
> Jens
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