On Mon, May 1, 2023 at 3:23 AM Gabriel Dos Reis <gdr_at_[hidden]> wrote:

> [Andrew]
>
> - I'm not sure what the deal is with _GLIBCXX_ASSERTIONS and
> __glibcxx_assert.
>
>
>
> When your programming language requires students to be exposed to that
> much trickery (where they reflective of production practices or not is
> irrelevant), I would expect that one would take and a pause and reflect on
> whether that is what should be happening, by default.
>
>
>
> Did you see my recent message to SG23?
>

This one: https://lists.isocpp.org/sg23/2023/04/0118.php

Have now. Thanks.


>
>
> -- Gaby
>
>
>
> *From:* Ext <ext-bounces_at_[hidden]> *On Behalf Of *Andrew Tomazos
> via Ext
> *Sent:* Sunday, April 30, 2023 10:10 AM
> *To:* Ville Voutilainen <ville.voutilainen_at_[hidden]>
> *Cc:* Andrew Tomazos <andrewtomazos_at_[hidden]>; sg20_at_[hidden];
> ext_at_[hidden]
> *Subject:* Re: [isocpp-ext] [SG20] namespace composition
>
>
>
>
>
>
>
> On Mon, May 1, 2023 at 3:01 AM Ville Voutilainen <
> ville.voutilainen_at_[hidden]> wrote:
>
> On Sun, 30 Apr 2023 at 19:50, Andrew Tomazos via SG20
> <sg20_at_[hidden]> wrote:
> >
> > On Mon, May 1, 2023 at 2:15 AM Gabriel Dos Reis via Ext <
> ext_at_[hidden]> wrote:
> >>
> >> Ideally, students should be taught practices they can deploy in
> production setting. While sanitizers and fuzzers have become accepted
> elements of the dev toolbox, they can't be deployed in production. That is
> part of why it is critical that we have a standard mechanism for turning
> bound checking on - or better yet, have bound checking on by default and
> have mechanism to opt out, after profiling data have shown that's what is
> needed.
> >
> >
> > If/when we ship contracts, aren't we going to eventually add them to the
> standard library to check preconditions? and bounds-checking of the
> standard containers would be amongst them? Isn't turning contracts
> on-and-off exactly that standard mechanism to turn bounds checking
> on-and-off? Or are we talking about bound-checking at the lower
> builtin-array level?
>
> We are talking about students that will be taught this year and the
> next. The forthcoming contracts don't arrive in time for that.
>
>
>
> Well then perhaps worth mentioning is that libstdc++ (at least) has
> something like it today. This is std::vector::operator[] from libstdc++
>
>
>
> reference
> operator[](size_type __n)
> {
> __glibcxx_requires_subscript(__n);
> return *(this->_M_impl._M_start + __n);
>
> }
>
>
>
> That __glibcxx_requires_subscript is like a C assert or something:
>
>
>
> #ifndef _GLIBCXX_ASSERTIONS
> # define __glibcxx_requires_subscript(_N)
> #else
> # define __glibcxx_requires_nonempty() __glibcxx_assert(!this->empty())
> #endif
>
>
>
> I'm not sure what the deal is with _GLIBCXX_ASSERTIONS and
> __glibcxx_assert. Maybe jwakely would know.
>
>
>
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>