public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "qinzhao at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/108896] provide "element_count" attribute to give more context to __builtin_dynamic_object_size() and -fsanitize=bounds Date: Wed, 01 Mar 2023 22:54:22 +0000 [thread overview] Message-ID: <bug-108896-4-BkuyRAZTJN@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-108896-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 --- Comment #5 from qinzhao at gcc dot gnu.org --- (In reply to Jakub Jelinek from comment #3) > (In reply to Richard Biener from comment #2) > > Iff only (GNU) C would accept the following ... > > > > struct foo { > > ... > > unsigned int count; > > ... > > int data[count]; > > }; > > Well, that I think conflicts with the variable length structures GNU > extension, where > if the array size of a field isn't a constant expression, it is an > expression evaluated at runtime once (SAVE_EXPR) to determine the field size. VLA is only legal inside function scopes. but this new extension will be legal at file scope. will this fact be used to distinguish these two? > Here we are talking about something similar to what Fortran wants with its > deferred length arrays, essentially to have the size evaluated each time it > is accessed. > With the data[count] form even if it would be disambiguated the question is > if we want to otherwise treat it like normal flexible array member e.g. for > sizeof etc. and only treat it specially for __bdos, or if it would affect > say sizeof too. the immediate purpose of this new extension is used for __bdos. is there any benefit if it will affect sizeof()? > I don't see how sizeof (struct foo) could be treated differently from > flexible array member, because one doesn't have an object on which count can > be evaluated, but perhaps > struct foo f; > f.count = 24; > sizeof (f.data) could change. what's the major purpose of enabling this?
next prev parent reply other threads:[~2023-03-01 22:54 UTC|newest] Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-02-22 21:26 [Bug c/108896] New: " kees at outflux dot net 2023-02-22 21:31 ` [Bug c/108896] " kees at outflux dot net 2023-02-22 21:32 ` pinskia at gcc dot gnu.org 2023-02-23 8:44 ` rguenth at gcc dot gnu.org 2023-02-23 9:10 ` jakub at gcc dot gnu.org 2023-02-24 15:44 ` muecker at gwdg dot de 2023-03-01 22:54 ` qinzhao at gcc dot gnu.org [this message] 2023-03-01 23:27 ` kees at outflux dot net 2023-03-02 15:50 ` muecker at gwdg dot de 2023-03-02 17:34 ` qinzhao at gcc dot gnu.org 2023-03-02 18:17 ` muecker at gwdg dot de 2023-03-02 18:34 ` muecker at gwdg dot de 2023-03-02 19:47 ` qinzhao at gcc dot gnu.org 2023-03-02 19:56 ` qinzhao at gcc dot gnu.org 2023-03-02 20:07 ` muecker at gwdg dot de 2023-03-03 20:27 ` isanbard at gmail dot com 2023-03-03 21:32 ` muecker at gwdg dot de 2023-03-03 23:18 ` isanbard at gmail dot com 2023-03-04 7:52 ` muecker at gwdg dot de 2023-03-06 19:15 ` isanbard at gmail dot com 2023-03-06 19:18 ` jakub at gcc dot gnu.org 2023-03-06 19:38 ` muecker at gwdg dot de 2023-03-06 19:57 ` muecker at gwdg dot de 2023-03-06 20:05 ` siddhesh at gcc dot gnu.org 2023-03-08 16:56 ` qinzhao at gcc dot gnu.org 2023-03-08 17:13 ` qinzhao at gcc dot gnu.org 2023-03-08 17:36 ` qinzhao at gcc dot gnu.org 2023-03-08 17:38 ` qinzhao at gcc dot gnu.org 2023-03-08 17:43 ` qinzhao at gcc dot gnu.org 2023-03-08 17:48 ` muecker at gwdg dot de 2023-03-08 18:37 ` muecker at gwdg dot de 2023-03-08 19:20 ` qinzhao at gcc dot gnu.org 2023-03-08 19:47 ` qinzhao at gcc dot gnu.org 2023-03-08 20:20 ` muecker at gwdg dot de 2023-03-08 20:47 ` qinzhao at gcc dot gnu.org 2023-03-29 16:12 ` muecker at gwdg dot de 2023-04-03 20:29 ` qinzhao at gcc dot gnu.org 2023-04-03 21:53 ` muecker at gwdg dot de 2023-04-04 15:07 ` qinzhao at gcc dot gnu.org 2023-04-04 16:33 ` muecker at gwdg dot de 2023-04-04 20:08 ` qinzhao at gcc dot gnu.org 2023-04-19 16:32 ` qinzhao at gcc dot gnu.org 2023-05-03 13:57 ` qinzhao at gcc dot gnu.org 2023-05-03 15:32 ` kees at outflux dot net 2023-05-04 15:16 ` muecker at gwdg dot de 2023-05-04 15:30 ` qinzhao at gcc dot gnu.org 2023-05-25 18:14 ` qinzhao at gcc dot gnu.org 2023-05-25 18:47 ` ndesaulniers at google dot com 2023-10-05 19:54 ` tg at mirbsd dot org 2023-10-05 20:21 ` muecker at gwdg dot de 2023-12-27 6:31 ` sean@rogue-research.com 2024-03-06 14:40 ` qinzhao at gcc dot gnu.org 2024-05-31 17:50 ` qinzhao at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-108896-4-BkuyRAZTJN@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).