Path: csiph.com!eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail From: Tim Rentsch Newsgroups: comp.lang.c++ Subject: Re: C++20 concepts rocks Date: Sun, 06 Feb 2022 05:54:24 -0800 Organization: A noiseless patient Spider Lines: 33 Message-ID: <86k0e8je27.fsf@linuxsc.com> References: <87k0easj5d.fsf@bsb.me.uk> <86a6f5lq76.fsf@linuxsc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: reader02.eternal-september.org; posting-host="a80c60510ddf69c3dc6a890da3a37a42"; logging-data="12851"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+IWpEBfchObq8+Pnt12L7MqtBaVwEU1U4=" User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.4 (gnu/linux) Cancel-Lock: sha1:eZ/+VYMs9rN+vpWxxgjzZQ1gay8= sha1:IdAMUtFMAIgR0WYSXnc4hsU0zGc= Xref: csiph.com comp.lang.c++:82938 "james...@alumni.caltech.edu" writes: > On Saturday, February 5, 2022 at 2:38:49 AM UTC-5, Tim Rentsch wrote: > >> "Alf P. Steinbach" writes: > > ... > >>> Nice, but I believe it's formal UB to move a pointer to `char` from >>> beyond an array into the array, and dereference it. >>> >>> The C committee wrote a rationale for their earlier decision to make >>> it so, instead of admitting that it was bludner. Uh, blunder. I >>> don't recall who provided that information, but someone in this >>> group. >> >> I suspect that you either are misremembering or have misunderstood. >> Usage patterns like that seen above are defined behavior in C, >> because they were in common use for at least 10 years before the >> first C standard. It would be unthinkable for WG14 to have turned >> it into undefined behavior. > > Though it's not clear from the above message, later messages > have made it clear that the concept he was talking about is the > one explained in the following sentence: [...] Yes, I already saw that. > Therefore, not only is it thinkable, it has in fact been > thought. [...] My statements are correct. It seems you have made some bad assumptions about the referents of what I was saying.