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Re: [wg14/wg21 liaison] [isocpp-sg21] Telecon to review P2388R1 Minimum Contract Support: either Ignore or Check_and_abort

From: Jens Maurer <Jens.Maurer_at_[hidden]>
Date: Wed, 22 Sep 2021 08:00:00 +0200
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.


> 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.


Received on 2021-09-22 01:00:14