It’s not an either or thing.

That’s like saying “we haven’t decided if the goal of WG21 is object
oriented programming or structured programming”.

On Mon, Oct 20, 2025 at 1:21 PM JOSE DANIEL GARCIA SANCHEZ <
josedaniel.garcia_at_[hidden]> wrote:

> We have never (to the best of my knowledge) decided if the goal of WG21 is
> functional safety or language safety.
>
> Let's keep in mind that there are external pressures to pursue language
> safety.In particular (but not only) memory safety.
>
>
> On Mon, Oct 20, 2025 at 10:08 PM Ryan McDougall via SG21 <
> sg21_at_[hidden]> wrote:
>
>> They are comparable because they both address the needs of Functional
>> Safety as per p3578 <http://wg21.link/p3578>. SG23 took a poll on
>> whether they're better than macros see P3297 <http://wg21.link/P3297>.
>>
>> I think it's not a leap of logic that EWG has strong consensus to pass
>> P2900 precisely because they feel it's strictly better than macros.
>>
>> Cheers,
>>
>> On Mon, Oct 20, 2025 at 12:58 PM John Spicer <jhs_at_[hidden]> wrote:
>>
>>> We have never taken a poll of whether P2900 is better then macro
>>> solutions.
>>>
>>> Could you explain why you think contracts and macro-based solutions are
>>> comperable?
>>>
>>> John.
>>>
>>> On Oct 20, 2025, at 3:09 PM, Ryan McDougall <mcdougall.ryan_at_[hidden]>
>>> wrote:
>>>
>>> I’m saying we have decades of experience with macro based systems, which
>>> defines the floor of features/expectations. The consensus is P2900 is
>>> better taken as a whole. There are things i think should be different with
>>> p2900, but p2900 represents consensus. There has been no evidence put
>>> forward that there is a more correct course. Based on those decades of
>>> experience here are no outstanding questions that having a TS would answer.
>>>
>>> If i am wrong, please list precise questions that a TS would answer. “We
>>> don’t have enough experience” is a statement.
>>>
>>> Cheers,
>>>
>>> On Mon, Oct 20, 2025 at 11:54 AM John Spicer <jhs_at_[hidden]> wrote:
>>>
>>>> You keep saying things like we have “decades of experience with
>>>> macro-based systems”.
>>>>
>>>> If contracts were remotely similar to macro-based systems, we would not
>>>> be having this discussion.
>>>>
>>>> The problem is that contracts are *vastly* different.
>>>>
>>>> If you put P2900 and macro-based systems in the same set, that means
>>>> you don’t understand one or the other.
>>>>
>>>> John.
>>>>
>>>> On Oct 20, 2025, at 2:22 PM, Ryan McDougall via SG21 <
>>>> sg21_at_[hidden]> wrote:
>>>>
>>>> The "course corrections" do not actually suggest a future course
>>>> (beyond asserting without evidence"we need more experience" and kicking the
>>>> can down the road to a TS) -- we've had years for alternative proposals to
>>>> be put forward, and none have surpassed P2900.
>>>>
>>>> We *do* have decades of experience with macro-based systems, we *do*
>>>> have decades of experience building software at scale (see Software
>>>> Engineering at Google <https://abseil.io/resources/swe-book>), and we
>>>> *do* know who our users are (see P1995 and P3297) -- and while there are
>>>> many variations on contracts, P2900 represents our best consensus
>>>> interpretation of those decades of experience. Not all of these decisions
>>>> were everyone's first choice, but P2900 is the consensus. There is no
>>>> evidence that any other option would improve that.
>>>>
>>>> Multiple papers, like P2900 and P3578 <http://wg21.link/p3578> explain
>>>> exactly who the feature is for, and how and why each of these design
>>>> choices were made. There is no reason to believe the current course is
>>>> incorrect, or that another course would be more correct.
>>>>
>>>> On Mon, Oct 20, 2025 at 4:58 AM Ville Voutilainen via SG21 <
>>>> sg21_at_[hidden]> wrote:
>>>>
>>>>> On Mon, 20 Oct 2025 at 14:34, Timur Doumler via SG15
>>>>> <sg15_at_[hidden]> wrote:
>>>>> > Given the above, it seems to me like opposing C++26 contract
>>>>> assertions because you want that checks are always on / always enforced is
>>>>> kinda like this:
>>>>> >
>>>>> > – Alice: "I want safer roads for pedestrians." (reasonable and good
>>>>> request)
>>>>> > – Bob: "Here's a proposal to fund bike lanes in the city."
>>>>> (reasonable and good proposal roughly in the same area but with a different
>>>>> goal)
>>>>> > – Alice: "But bike lanes don't add more crosswalks or reduce speed
>>>>> limits. So they don't make roads safer for pedestrians. Therefore, we
>>>>> should not build bike lanes."
>>>>> >
>>>>> > Here, Alice is committing a logical fallacy. Just because bike lanes
>>>>> are not useful for Alice, it doesn't mean that they're not useful for Bob,
>>>>> and taking away bike lanes from Bob does nothing to give Alice what she
>>>>> wants.
>>>>>
>>>>> The colorful analogy doesn't include considerations where providing
>>>>> bike lanes for Bob and doing nothing else is not entirely harmless for
>>>>> the pedestrians Alice is focused on.
>>>>>
>>>>> It's also incorrect in its suggestion that bike lanes are not useful
>>>>> for Alice. Nobody has said that P2900 isn't useful. That's why it's
>>>>> included
>>>>> in *every* *single* *one* of the currently active proposals suggesting
>>>>> course corrections.
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>>>>>
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